84 Year Old Radio Receiver Restoration! Stromberg-Carlson 145L

hi everyone and welcome to another episode of mr carlson's lab today we're going to electrically restore a pretty high-tech radio receiver from the 1930s so high tech in fact that many companies even today are still using this same kind of idea this radio also has the ability to receive high fidelity am so together we're going to electrically restore this radio receiver align it and then we'll see how well it performs we're going to make it perform like it did back in the 1930s so let's get started here's the radio that we're going to be electrically restoring today as you can see for the 1930s this is an extremely complex radio and was worth a lot of money really this thing is a communications receiver in a wooden case they did a beautiful job on the woodwork this is all the original woodwork and as you can see in the grill cloth down below that gold looking grill cloth in the leaf just the amount of effort put into that alone to make it look that good all original so this radio is an excellent example to do electrical restoration on and then we can see how this thing will perform so after the restoration this thing should perform just like it did back in the early 1930s so everything works all the the dials and everything moves so there's no problems with that the little indicators for the fidelity and the volume on the top so you'll see fidelity right here and volume little indicators move back and forth there's two little sliders in there it has a trifocal tuning electric eye it's got all the neat stuff so it should be a great electrical restoration so what i'm going to do now is i'll turn this unit around and we'll take a look at the back side just before i take the cabinet out and get started on the back side of the radio you can see that big label that says acoustical labyrinth so if you look into some modern day ideas dealing with sound you'll find that some modern companies are using something that's very similar to this design that was used back in the 1930s we look up just a little bit you'll see the cardboard pipes running from the back side of the speaker down into the acoustical labyrinth right in the center of the speaker right there is an electromagnet this is before speakers had permanent magnets so the high voltage from the radio goes through that cloth cord that big transformer on the corner there the high voltage created by that transformer and rectified by that tube goes through this brown wire right here into that electromagnet and it magnetizes it so the current draw of the entire radio is usually placed upon that now in some designs it isn't and i haven't looked at the schematic for this yet so it may or may not run through that some of them will have a separate inductor in line with high voltage to filter out any type of hum or anything like that so we'll take a look at the schematic here in just a little bit and see where they've actually placed the electromagnet down here in the electrical design lots of tubes on the chassis very complex chassis for the 30s again very expensive high-end receiver so being expensive and high-end and in such good condition this will be a lot of fun to electrically restore and see how this thing performed way back when i bet you it performs very close to a lot of modern receivers all right i've got the back side off here so i'll show you that i've moved it out of the way already many screws later lots of screws around the perimeter here and around the two cardboard pipes that run into the labyrinth so i removed all that so now this thing should just slide right out and let's take a look at what's inside this thing this should be exciting [Music] that wasn't too bad i thought this would be stuck in there but that actually came out very easy okay so i'll just slide this over here for a moment we can see that we have a port on the bottom here and it also looks like there's a bit of a port or a catch for the bottom side of the speaker as well here look at these pipes that's pretty high tech for the 30s look at that and if you look you can see the actual the path that goes down that way and then there's an opening down in there you can see that and it goes through kind of in a zigzag pattern through the labyrinth so i know many of you are gonna look this up and again you'll see some modern companies are using the same sort of idea that stromberg carlson was using way back in the 30s pretty neat stuff still really nice and solid in excellent condition as well so now what i need to do is disconnect the speaker so i'll unplug this wire from the radio chassis and take the screws out because i can't service the radio unless the speaker is attached again there's current going through this and into the radio right so the speaker has to be there when the chassis above which is outside the shop right now which is serviced so we'll get all of that taken out get this on the bench and we'll take a look at the chassis and the underside that's where the real interesting stuff is the speaker is in really nice condition you can see the seal for that box in the back side of the speaker cabinet there the labyrinth i guess you could call it big electromagnet some of the paint is coming off not a big deal you can see they've bent this nice piece of thick metal here and they've used an arc welder to tack it into place so very nicely done now the paper that they're using it almost looks like it's plasticized which is very interesting it doesn't feel like paper it almost it feels like plastic but yet it has the grain of paper it's very interesting it has a felt surround really soft felt and the travel of the speaker is very fluid lots of travel there probably see it on an angle better lots of travel there is no from each side here no binding at all it's absolutely flawless so when you come across an older speaker like this you can actually adjust this in the center if it's binding you can loosen this off and readjust it by sticking shims down in here and then re-tightening it back up that really makes a a big difference especially if the coil is touching the magnet the electromagnet or anything you'll notice that all the lows will go away and it'll kind of sound like you know you're talking with a pinched nose whereas in this case everything is very very fluid it's working very very well i can see that right here so the speaker itself is just in absolutely fantastic condition it you know the surround is very soft so this should develop low frequencies very nicely it's a really nice example of a you know an old electromagnetic speaker right here i don't know if it gets any better than this to tell you the truth that speaker is just absolutely fantastic so i'll go grab the radio chassis because all of this stuff is almost too big to fit on this bench right here so i'll move this out of the way and i'll go grab the radio chassis we'll take a look inside and see what we're up against with that here's a look at the top side of the chassis and as you can see it has a lot of tubes in it so these are all tubes here and here all over here here and then there's a magic eye tube at the top it's got this monster power transformer which makes this chassis very heavy and it's also difficult to get out of the cabinet because you have to bring the chassis back and then tip it forward so you have to tip it on an angle because the dial glass in the front is so high that it actually doesn't come out of the cabinet square so difficult to get out and again very heavy now this radio receiver has a lot of power delivering capability so it can i guess you could say drive a speaker quite nicely so these are the audio output tubes right here you can see how these how big these metal tubes are and they're 6l6s so you know this thing is definitely going to uh produce some audio let's put it that way they used a really big rectifier as a 5z 3 here because you know this thing obviously has some current demand with all of these tubes so if transformers over here and of course we have the antenna oscillator and rf section over here all the tuning will be you know this will be quite uh quite a job to tune this thing there are a lot of spots to tune here and of course with the if being variable it definitely makes for an interesting tuning job so i'll just move this forward here and this chassis is so heavy so i'll just put this here and take a look at the dial face so it's in absolutely fantastic condition again so you can see they have dial strings here it'd be nice if i could get all of this into the shot at the same time here okay i think that's about good so you can see all these dial strings here and you can see that when i move this you look at the volume up here now there's a light behind that and it actually shows you your volume level here by moving this little red bar in and out so a little disc is turning in there and then the fidelity is the same way so the fidelity control you can see moves up and then it gets to about halfway and then it hits a hard spot but you can still move it quite easily now what's happening in here is there's a cam underneath the chassis that's moving slugs up and down inside of the iaf transformers we'll take a look at that shortly there is a bottom on this radio receiver here and i haven't removed this yet there is only one screw in it so we'll discover the fun together we'll see what's underneath this thing and it's yeah the bottom is even in very nice condition very interesting choice of chassis paint really nice look to it so i would move this around this is just going to move around the actual the dial indicator behind here but i would need a knob on this to move this because it's you know has a an actual a ratcheting function inside so it holds it into each position of the selector switch which moves this up and down so it takes quite a bit of force to move this and then of course this is just a you know standard on off switch and a potentiometer variable resistor behind it so what i'll do is i'll flip this thing upside down i've got to do this very carefully you know what have to be very careful with this dial gloss and everything like that and we'll take a look under this cardboard cover and see if anything has happened over time it's obviously been serviced there's nice big hole here where probably some filter can has been removed or something like that so it looks like it's actually painted and i would imagine something was sitting there it was has just been removed all right let's take a look at the underside there's only one screw in the bottom here so obviously people have been in here before not me somebody else has been in this thing i have worked on these chassis before but not this one look at this moisture resistant moisture resisting fiber all right no cost spared here whoa no restorations done here looks like it's been patched up through time though and look at wow look at this tar's even melting on that transformer i'll grab the bottom here again let's take a look yep there it is why is this here well because of these so what happens is these capacitors end up shorting out or becoming resistors and they cause circuitry in the radio to draw a heavy current and that heats up components the components get hot the tar melts and starts to flow and you can see this one here is a little bit of tar on it as well so it's quite a ways away from the edge of the chassis here so components have definitely gotten hot this one here really hot so hopefully that's still okay we'll find that out when we verify the radio so the most common thing that destroys these old radio receivers is when these are purchased people tend to grab these things and they bring them home and they think oh you know i want to just plug it in and see if it works and when you do that what happens is these capacitors they end up shorting the electrolytics and even these old paper and foil type capacitors they end up shorting out and they burn components out inside of the radio and sometimes even the large power transformer that's way down in here so if the power transformer burns out that's kind of a crucial component on these chassis and you have to end up looking around to find a replacement look at how hot this one has gotten the actual color bands have changed on this and well what's attached to this lead a sealed tight capacitor sealed tight to keep the leakage in so you know definitely bad components all over the place so anyways what destroys these things is these cylindrical things right here so all of these have to go so this has to go this this this this this this this this this this this this this this oh i can go forever so there's a lot of them in here that have to go so what i'll do is i'll remove these these very easily come out just remove these screws here on this side and on this side down here and then i can take these out and i have a nice free you know area to work in here and i can start replacing all of these components this is the variable iaf right here you can see these slugs there's a slug here and a slug over here that'll move up and down with this control see that now these are moving up and down so there's a tone control here is a variable resistor here and then this comes down here and then we can move this up and down this will change the fidelity so we'll take a look at this on a spectrum analyzer you're probably asking why aren't you working on this on the bigger bench on the old time workbench well reason being is because i don't have the 3585 b spectrum analyzer out there and we want to take a look at the iaf in this thing so i have to do it on this bench so there are some original capacitors this one here says stromberg carlson on it i can see the people that have put this together have actually spent the time to put the capacitors in the correct way you can see outside foil mentioned here that ties to the chassis outside foil ties to the chassis and you can see here we have the outside foil end tied to the chassis so they have spent the time to put this thing together correctly so as i've mentioned before whenever you're working on a radio receiver like this it's worth the time to to locate the outside foil on the newer style capacitors because they aren't marked and i've designed a little device to do that and i've released that the plans and schematics and everything for that on patreon so you can take your new capacitors locate the outside foil and put in your new replacement capacitors the correct way so they spent quite a bit of time to make sure that this is all done correctly when they put these things out of the factory so you want to make sure that when you're doing your restoration job that you take as much time to do the job correct as well now what i'll do is i'm going to start replacing all of these caps here and when i have that done i'll come back and we'll talk some more about this so what i'll do in the next shot is i'll tell you the amount of time it took for me to replace all of these capacitors i.e okay it's been two days since the last shot or it's been a day because you really can't tell because in seconds it blends into the next shot right and i'll give you an idea of how long it takes me to do this now i don't uh you know cut corners and do the j hooking method a lot of people like to do that they'll just you know cut the capacitor and leave a little bit of lead and then put the new capacitor in and then j hook the leads together i i don't do that i'll actually remove the lead right from the terminal tie strip and i'll put the capacitors in like they were at the factory so i'll install them like that so that takes a little bit more time to do that but i just i prefer that method so i'll get that all underway and then we'll go through this and start testing some resistors i'll even keep some of these capacitors out and we can test them and i'll give you an idea of how these things fail i'm interested in testing the stromberg carlson capacitor that's a an original device right there and yeah it's put in the correct way the band end is here and that's right to the braid over here so everything is uh you know they spent the time to do this correctly and even the people that were in here later on that did the work like this looks like a replacement part right here they even put that in the correct way too so the technician that was in here at some point in you know this thing's repair history did understand that it's very important to do that and i'll talk more about why it's important to actually put these things in the correct way even though the newer capacitors don't have it marked just before i start recapping this thing which at this point looks like an endless job i was going to show you a modification that somebody has done throughout time i don't know when this has been done at any rate somebody has cut one of the capacitors here and then tied some shielded lines in and you know reattached it to the volume control so that you could pump some form of external music source or something in here at any rate so i want to return this thing back to factory spec as close as i can so we can get a really good idea of how this thing sounded back in the 1930s so all of these modifications are all going to be taken out because when modifications are done like this sometimes they introduce hum even though they have shielded cabling just because of their ground connections and things like that and i don't want to introduce any other issues from other people's in this case scary looking modifications it's black tape up here taped to a resistor and all this kind of stuff green wire running off to here just you know some pretty scary workmanship so this has been done over time and this is very common when you work on radio chassis like this a lot of the times you'll find yourself referring to the schematic to go okay so what's been done doesn't make sense let's try and figure this out kind of thing so i will show you the schematic here in a little bit and we'll go over it and i'll briefly explain the way that this radio operates i have already gone over the entire schematic for this radio receiver up on patreon i spent a lot of time explaining all the different parts and sections in it as there is a schematic series going on up there right now so at any rate i will go over it briefly here as well and show you what's been done and do a brief explanation of this circuit for all of you as well through the magic of the camera what you see here is about 16 hours worth of work give or take a half an hour or something like that so it's been roughly 16 hours since the last video clip and these are all the components that have been replaced in the bottom side of that chassis and in a moment we'll take a look at the bottom side of the chassis and i'll show you how i've mounted all the new components now you may look at this and say well you know it doesn't look like a whole bunch of parts why did it take 16 hours i was actually working pretty quick reason being is you have to move other pieces out of the way and as you're you know replacing components you're also testing other components that are attached to the same tie point so you don't solder a new component and have to go back later test the component and then remove let's say a faulty resistor so for example if this was tied to a tube socket and this was tied to a tube socket here well i'm not just going to desolder the capacitor right and then replace the capacitor and then come back later on and then test the resistor find that it's faulty then have to desolder both of these again remove this put a new one in and then re-solder it so there is quite a bit of time in just basically going through everything and testing all the components to make sure that they are close to value now when you're replacing these components you can optimize the design and it's just due to the newer components you can get grounds closer to where they need to be instead of running it to a remote part of the the chassis you can actually you know ground it directly say if it's a bypass capacitor you can go right from the screen to the cathode or very close to it on the chassis area you can really optimize things and that's just due to component size now so for example this capacitor here is the cathode capacitor on the 6l6 tubes and this is located way across the chassis because of its size right you can see it's pretty large capacitor so this capacitor here is replaced with this capacitor right here one of these caps so you can see that the difference in size now these are very good temperature ratings as well so i can mount this very close to the socket of the 6l6 and ground it right beside it which again optimizes the design i don't need to carry a wire all the way from the cathodes of the 6l6 across the entire chassis and then you know mount this way far away so things like that and that really helps an rf service too whenever you're installing bypass capacitors in rf service you want to keep them as close to the device as possible you don't want long leads because long leads act as inductors and they also pick up noise and sensitive applications so i'll talk about that when i get the chassis here and i'll give you some of my ideas and thoughts as i've gone through this and optimize things as i've been replacing components here's another capacitor something like this here brand new we'll replace this right here okay so and they even get smaller than this this is a fair size capacitor you can get these capacitors i guess you could say size optimized as well and i'm not really too worried about that these are very long life high temperature capacitors that i use so i'm doubting that those will need to get replaced for an extremely long time very high quality electrolytics i have entire lists i've spent time grading countless hours grading and testing components and verifying them in order to use in these older radio receivers so that you know it keeps the radio receiver working incredibly long i have those lists up on patreon i have a couple of those verified components lists up there with part numbers and everything so if you're restoring radios that may be beneficial to you because i'm i guess you could say a little bit picky about what i do so what i'll do is i'll test some of these components here and i'll show you where the you know the real problems were and just by removing these components and testing them i can tell where the radio would have failed so i don't even need to turn the radio on to to do this i can just go okay this is bad so that means that this is going to happen or this is faulty so this is the result of that being faulty so what i'll do is i'll start explaining some of this i'll get a schematic in the shot and we'll test the famous death capacitor as well so this is a the capacitor that's across the ac line and tied to the chassis now these capacitors are you know it's given a pretty strong term and they call them the death caps but really what happens with these things is they end up short or becoming electrically leaky and they bring the ac line onto the radio chassis so this is that capacitor in that radio we'll test this as well and uh you know we'll see exactly what's gone wrong in here and i'll explain all about all of these components here so i'll go grab a schematic and some tools here and i'll talk about that and then i'll grab the radio chassis and i'll tell you where i've replaced things and why i've done it like that okay so here's the schematic and for any of you that are owning one of these stromberg carlson radios they're very cryptic about these resistors that are basically sealed in a block they don't have any resistance ratings listed anywhere so what ends up happening is capacitors fail in these radio receivers and that resistor block goes open and then you're left scratching your head going what really was the resistance value there so i've taken the time to mark that off so any of you that have a failing one of these radios that say that has that burnt out resistor block and it's very common when capacitors fail and people operate the radios right so when this fails these are the resistance values so there's three resistors inside that resistor block and i'll show you that here when we look at the bottom of the chassis i actually just write right on the resistor right on the little strip that holds it down i write the resistance values so in the future if something ever does go wrong it can very easily be replaced by somebody else or myself right so these are the values so we have a 630 ohm resistor right at the top here there's a 12 k ohm resistor right here and then this resistor is completely separate this is the cathode resistor for the six l sixes right here all right so it's two resistors that are put together and then one separated one at the bottom and those are the values again i'll cover that when we look at the bottom side of the chassis again i'll show you the resistor i actually put a piece of thermal transfer silicone underneath it so that it will trans transfer the heat to the chassis and use the chassis as more of a sink and it also uh it uh you know keeps it tight in the bracket because a lot of the times they come loose because just the plastic changes size over the years and then they get a little bit loose and then they don't properly transfer heat to the chassis anymore okay so i'll show you that as well lots of little things that have been done in here so this capacitor here the death capacitor is these two right here so you can see it has a common ground to the chassis i'll zoom in on this i don't know i've got my exposure fixed right now i think that's going to be okay so the brightness is staying all right okay so that's the the center connection which is the shell of this capacitor and then this is each capacitor each one of these leads is a lead off to the line side there now as you can see this is put together properly stromberg carlson used their brain when they were putting this thing together you can see the very first thing in line is the fuse and then after that is the switch and then after the switch are the capacitors so if this ever fails it's not right across the line at the line cord it's beyond the fuse so the fuse will go away if this was to say dead short across these two wires okay a lot of new designs they don't do that they have the fuse in other places and things like that you can even see there's a different version of the stromberg carlson that has a phono adapter and it's kind of a skyscrapery looking radio it's a pretty sought after very rare unit as well and you can see that they've got the phonograph after the fuse and the switch as well so everything is protected by that first fuse in line that's very important in a in a good design so this capacitor here is replaced with a modern x1 y2 rated capacitor so there's two of them all right one for each one they're x1 y2 so they're they have very good safety ratings they're actually a certified safety capacitor so when they fail they fail in the correct mode they don't you know cause issues okay so they're known as x1 y2 rated safety capacitors if you're more interested in that you can look those up in fact i have a bunch of those capacitors again listed on that verified i believe they're in the verified components list that may have been done after that if not it'll get added at any rate so these resistors here are the ones that i just talked about that long one on the back side of the chassis these capacitors here have all been replaced by these you know modern caps right here and then of course this cathode capacitor right here is the one that was you know replaced by these little guys right here all right my focus is right here there we go all right 105 degree rated caps long life you know very important now get rid of this thing so these capacitors here these two want to hang out together so these ones these ones here are down here so there's one of them that's down here all right that's right across this this particular unit right here and right to ground so it's funny they show a dot in the center but they don't show it tied off to ground but it is actually tied off to ground so one of these caps right here and there's a few things in the parts list here that aren't even listed which is kind of interesting the parts have a number on here but they're not listed i.e you know part number 175 isn't on the list things like that anyways these capacitors here this is a um basically a 10 kilohertz filter right here here so to keep the highs you know i i guess at bay you could say because the iaf and this thing is very wide and with these two variable if transformers you're going to get some pretty high fidelity sounding am out of this thing so there's a bunch of these things in here you can see i've replaced these here now it's kind of a little bit odd because there's they use two different types of capacitors you can see this one says mica mold on it okay so the mica molds these 100 picofarad capacitors are leaky now a normal capacitor tester won't detect this so these look fine on a normal cap tester even on a normal leakage tester they look absolutely fine but these are actually leaky they are degrading now there are other capacitors in the actual radio chassis that say made in canada and i'll show you those ones there those ones are all okay it's just these mica mold ones here that are you know a problem here especially the ones that seem to have the two leads sticking out there's another one here that was uh doing some work in the rf band switching section okay so this one here i had to remove this resistor from this one side here to test this right because this would act as leakage rate and yeah all of these mica molds here they seem to be you know creating a bit of an issue so that this one capacitor here was in the rf section here somewhere where was it again it was this one here it was this one here and then there's a a resistor across one of these right here you can see this here this resistor goes right across this one right here so this was replaced with newer mica capacitors right uh let's see what else can i tell you here about this is so many parts and pieces all over this these uh 47k ohm resistors were moved up in value the cathode bypass capacitor this one here is virtually open so it would have really lost the bottom end response and that's this capacitor right here would have really lost the bottom end response and the loudness effect would have you know really gone way down on this this part here is a part that's gotten very hot and of course that's because of failed components this radio was being used let's pack this out here this radio here was being used uh like this up until not long ago so the um there has been heating in some components that would um yeah it is definitely apparent as i've mentioned before and some of these capacitors are so incredibly bad some of the resi the original capacitors in this unit are so incredibly bad this thing was on the verge of a really catastrophic failure so and i'll give you an example of that here quite shortly so lots of parts and pieces replaced throughout this entire unit whenever you're working on one of these radios there's a little part that hides by the tuning eye and it's usually right in the tuning eye cap itself that one always should be checked it's usually a one mega ohm resistor so there are discrepancies in parts in the parts lists of a lot of these radios i've noticed lots of discrepancies in this as well so i've gone with appropriate values that make sense to other sections now it could be the discrepancy that i'm seeing has been a component replaced by a technician down the line for example when i was looking at this this didn't look right all right so this uh 2.5 k ohm resistor is actually supposed to be 560 ohms all right so there would have been quite a bit of voltage drop across this one device and it would have caused the receiver to be not as sensitive as it could be okay so i replaced this with the appropriate value and of course you know we're yet to test this thing out we'll see how it all works when we turn it on for the first time this value here is one of those 560 ohm resistors it's been very very hot and it's because one of these capacitors was very very leaky i believe this one here was attached to it so this is one of those um really horrible sealed type capacitors as you can see it's it's had better days so and there's another one over here too different color red solar seal tight capacitor high temperature molded capacitor that uh spits chunks of its molding off when it gets hot i guess you can see that there at any rate yeah all just all really really bad so all of these capacitors here no matter how you test them are going to be you know bad in some way shape or form you'll find some that are better than others and these are kind of odd because usually these capacitors are very good mica mold makes very good capacitors this may have just been a series maybe it's because they've molded two of them in one unit that might actually be the the issue with this so i don't know why these mica molds are like this but they are nice looking little capacitors now i always save all of these things i'll put them in a bag and they end up in a box and i can use these as reference in the future and then when people want to know oh hey you know i have one of these capacitors inside my radio receiver do you think it would be bad i.e one of these i can go yes when i test these things now you'll test it on your normal tester and it'll look fine but if you do an extensive test with the capacitor tester that i've created you can really see the problem in this i created that capacitor tester because i was working on transmitting gear and uh some very high voltage mica capacitors were not showing any problems on any test equipment even modern stuff so i had to design my own piece of test equipment to find the problems and it sure enough did it found a problem i replaced the mica cap and the transmitter was back in service and nice and happy again so anyways i'll show you that here in just a little bit as well so anyways this is the you know just a quick run over of the components here i'll get some test equipment and i'll show you exactly why these things are failing and what's going on inside here's a very good capacitor leakage tester that's readily available on the used market today when they're rebuilt they're very sensitive and they work very well however when testing some capacitors they just aren't sensitive enough even in the mica position which is the most sensitive leakage testing position that this capacitor tester has now these capacitor testers they put quite a bit of applied voltage across the device to test it as you can see this one here will put up to 600 volts across the device and keep in mind the current is low but that is still 600 volts and caution needs to be used whenever you are using one of these devices so if you ever do get one of these things definitely follow the safety instructions that are you know issued with the device and it's always a good idea to keep it in the discharge position the switches aren't spring-loaded at least in this model it isn't so it won't automatically pop back to discharge you always want to make sure before you touch the leads or anything that it's in discharge and the voltage is turned right back down to its minimum that's just a few extra safety precautions when using a device like this so keep in mind if you are going to purchase something like this and use it you are definitely doing so at your own risk be careful this device that i've designed is a low voltage tester so much much safer to use and it's much more sensitive as well it's designed to find those obscure issues and i'll give you an example of that right now so so here's one of those capacitors that i've taken out that on this unit will test absolutely fine but this one here will show the failure point so i've mentioned this before okay in many of my other videos about these types of capacitors in the oscillator and rf section if you don't have to replace these mica mold or mica capacitors in those sections definitely don't do it so you want to test them to make sure that they're not faulty but if you don't have to replace them don't just replace them for the sake of putting in a modern part reason being again as i've mentioned in earlier videos is at the factory many of these are hand-picked and what they've done is they've optimized on the values to make the dial on the radio track correctly if these are in the oscillator section and even in the rf section you need to be very very careful with these caps you don't want to be replacing these things unless they're absolutely necessary so i hear so many people saying oh i just took out all the capacitors and i just replaced all the capacitors and i started from there but now you know 600 am is somewhere around 650 and i just can't get it to you know to line up again a lot of these things they were hand picked to make sure that the dials track correctly so something that may say 100 picofarad that's what this means right here 100 picofarad may not necessarily be 100 picofarad if it's handpicked it might be 112. all right so and then all of them that are used in those series of radios they may have bought just tons of 100s and they just hand picked all the 112s and that made their radios work all that much better so keep that in mind when you're restoring these old radios these should always be tested and not just blindly replaced wax capacitors and electrolytics like this you don't even think twice about they can come out right okay so i'll give you an example of this here so what i'll do is i'll attach the test leads of this to this capacitor here all right now i don't want to hold the boots because this thing here has told me that these boots are mildly conductive and i don't want to be touching those so i'll hold the insulated leads here so i'll click this on to leakage if this is bad that i should close okay that's right up to 600 volts so it shows it as being okay okay so i'll turn that back down again and hit discharge to show you that the capacitor tester is working i'll just clip this here and i'll click this onto leakage and as you can see it's just you know three volts whatever it doesn't matter where you go it's faulty right because it's dead shorted this way all right so you can see that i'll test the other half as well okay so i'll put that over there all right hold these apart like so let it fall like that leakage right up to the top 600 across it right down to the bottom nothing's happening so it shows this as being an okay component click discharge all right always in discharge so now i'll move this over to here all right so now what i'll do is i'll test this in the forecasting position here so there's two scales that are indicated by these leds here this is a newer newer release of the board i've had many uh patrons that have asked hey you know can you give this a you know a larger more broad scale and something that can be calibrated to a resistance reading and this thing can so at any rate this is the one of the newer designs so what i'll do is i'll put this here all the designs work anyone that you make works this is just i guess you could say [Music] something that is more optimized if you want to actually you know get an idea of the actual resistance of the the device or where it's leaking so put this across here again i won't hold the boots because the boots are mildly conductive and this will pick it up so hold it back here okay so this is in the forecast position so if it's red it's really bad if the scale is yellow it's on the second scale down towards the green light here so this is discharge okay so it's green and then i'll click it onto test now there you have it it's showing the issue see the light's red and we're only one led in from the end so that's just over one gig ohm okay so this can count all the way down here yet before this goes green so hit discharge okay and here we go again this is a faulty device so i'll test the other one i'll shut it off move this over to here i'll test the other capacitor on here and just make sure that nothing is touching okay so here we go and that one's just a little worse than the other one okay oh no it's coming down a little bit it's still very bad so they're very very close together at any rate so now to give you an idea of how a good capacitor will test so this is 100 pico farad okay so if you were to test this on a normal capacitor tester i'm going to grab just a normal cap tester here let's move this up here i'll put this on a 200 picofarad scale what you're seeing is just its own capacitance here between these two things i'll just plug two of these in here so bend this lead out of the way and i'll just plug these two into the fixture here and get my hands away from it if it'll fit these are some pretty thick leads there it is okay so there you go you can see it's in there tested 108 so you'd think that it's okay the capacitance is okay but it is turning into a resistor so what i'll do is i'll pull this out of here and i will give you an example of this capacitor so this is a another mica capacitor this one here is 100 picofarad same kind of deal 104 all right so what i'll do is i'll put this one into these leads now now keep in mind that this here is just another mica just like the other one this is just a different package okay so there you go in the leads now watch what happens look at that no problems that's beyond 40 billion ohms shut that off that was through the discharge and one more test no problems okay so that's how most capacitors are all these micas should test in the forecast position see if i have another one on the bench here i do have that one off this side what is this one 3900 picofarad okay so this one here should be 3900 let's see what it reads on here make sure i am not leading any of you a stray i'll put this in here this should be about it 20 nano yeah so there you go 3.87 so 3 900. 3.87 nano for add or 3 900 picofarad very close to okay all right so let's test this one now this one here is quite a quite a bit larger in value so let's test this one here on this okay so no problems again discharge and here we go no problems so you can see if i just put my fingers across it you know i make the machine look like or think that i'm a dead short here see how bad this one is this one is rated at uh 0.1 microfarad so put this in here and click leakage wow so there you go this one's leaking at six volts and this one is rated at what 200 this is rated to go to 200 volts all right so this one isn't really effectively turning into a resistor so let's see what this does here down to three see what it does on this still on the test position hold that up there yikes so the second light between the first and second light we're looking at you know 10 meg ohms of resistance this one is really bad see that's going to be about 10 meg ohms of resistance that's only one light into the red into the bad scale so this is really bad so this is virtually you know a dead short up to a mega ohm this is around you know 10 meg ohms are in that area here so i'll shut that off let's uh for the fun of it let's just take a look at this now keep a crop keep in mind that those things are across the supply lines in here right and these are the ones that just destroy the radio so i'll turn this on get my leads here onto ohms get some brightness here hopefully you can see that i'll move the focus onto the screen just in case it's hazy all right so here's our cap let's read its resistance just for the fun of it so it should be in the area of 10 or something like that look at that so it'll keep counting for a while so now you can see like we're at three meg ohms right now and it'll probably settle off if i let this sit for a little bit it'll you know settle off somewhere this other cap maybe this uh tester here may actually give me a quicker reading i know that that really doesn't apply a whole lot of current so here let's try this one maybe i can get a quicker reading on this here and here and we'll go say there's a 20 meg ohm range i'll put this here and let's see if we can get any kind of a quicker reading off of this so there you go all right six meg ohms almost seven meg ohms all right here is a good point one so you can test this here see what happens you'll see there's an open connection right it'll go right see it's open all right and if we test this with the other meter which goes way up into the migs let me test that with this one here now this is uh only going to apply a very light amount of current see what this does here this here and here beyond 500 mega ohms right there right the reason it's climbing up slow is because it's charging the cap right so it's beyond 500 meg ohms which is absolutely fine you know and of course this these things test great on these capacitors here these are all on that verified parts list you'll notice that radio has a ton of those inside of it so at any rate there you have an example of why you may possibly want to build something like this so if you do want to build this all the plans are up on patreon and you'll find out that this thing is uh very beneficial to have on the bench i use this continually in fact just for the fun of it as i'm removing components i actually test it with this to see how bad they are and as you can see that one there you know it may settle off you know around you know well this is what just about seven seven mega ohms something like that it'll set off settle off around that area the first lights about one mega ohm to a short the second one will go to about ten in a bit and then the third one is going up and this here is just about one gig ohm one gig ohm and then when the scale flips again to the yellow it's a giganome and that's all the way to 40 billion ohms this tests so if there's any leakage through moisture aggression in any of your capacitors or anything like that this detects it that's the reason i had to build this is to fix that transmitter and that transmitter you know as i say it no problems in fact it's still in service so no issues whatsoever with that thing now keep in mind all the previous versions that you've seen to this test this pretty close to the same range as this one this one has one extra added range so you can see when capacitors are charging that's why it's a dual color they're all on patreon all of these things i've created are up there so if you want to build something like this for yourself you can do that and of course the the foil side tester is there as well this is the tests for the outside foil i'll give you an example here i do this with every single cap and mark them because these ones don't have the outside foil listed so i'll turn this on and hold my hands up here i'll insert some noise into this cap so the led with the least amount of leds lit indicates the foil side so this is the foil side see noise and no noise okay so the least amount of leds with the led here that's lit indicates the foil side if i touch this i ground myself out that's the reason you can see i'm doing this here so i'm acting as the noise antenna for these things this is up there as well so this is an adjustable sensitivity setting for all sorts of different capacitors and it also has an intensified position here for those really really sensitive ones you're having a hard time locating the outside foil on you can see how just clear that is right so outside foil this side so then what i would do is i would take this capacitor here and then take my little fancy pen here and get the cap off and then put a little dot here just like so and that little dot now indicates the outside foil end and this is marked for use so to give an example even though these capacitors are leaky they will have an outside foil so you can see that this one here clearly marks outside foil on one side outside foil all right so put this here and this here and so this side here should be the least amount of lights again we'll just get a little bit more hum into it not much there we go so that's the least amount of lights on that side you see the outside foil isn't as pronounced on this older capacitor it might also be that i have the sensitivity way up as well there you go the least amount of lights the corresponding led is the outside foil end and again it's this side right here and as you can see it says outside foil so if i flip this around you'll see the effect on the other side okay so i'll just remove this and i'll turn this around so this should be now the least amount of leds indicating the outside foil end is on this side right see that so it's flipped around now again very useful for when you're working on radio gear to put these things in the correct way especially for bypass service and things like that as well another project that's up there ready for you to build with all the plans and schematics and everything so it's just two of them i have a lot of these little devices up there that i've designed so if you feel that these may be beneficial to you definitely head on to patreon and check those out for those of you that have never seen resistors like this they read just the same as normal resistors except their coding is a little bit different so if you can remember bed or bell you can very easily decode these resistors in the future bed is very easy to remember body and dot or bell as in body and line so the body is the majority of the color so the body is yellow on this which is four the end is purple which is seven and then the line is orange which is the number three so you can directly convert that last one into zeros so four seven and then three zeros so 47 k ohms is what this is or 47 000 ohms now a lot of these are body and dots so there's just a little dot on the body they don't have an entire line drawn around it either or pretty much the same type of deal all right so let's test this one here this is the same type right here so we'll just go across this one here and as you can see that's a long ways away from 47k ohms it's 55k i mean that was replaced here's another one same value look at that 61k ohms so these are way off right this one here was supposed to be 500 560 ohms was supposed to be somebody to replace this and it turns out that this one here is 220 ohms so all the colors are burnt on this and this is obviously this is most likely from that bad sealed type capacitor nothing else there's nothing that should really heat this resistor that hot so this one right here is the reason that this one got so hot so this is dragging there's b plus on one side of this and then of course this is dragging the other side down making this thing change color and even the color bands have changed it's hard to read now so that was replaced and then this resistor here was in a spot where there should have been another 516 ohm resistor this one here may be okay so i should be 2.5 k that's 2.8 not too bad at any rate so this was replaced with a you know 560 ohm resistor again that's just a sum of them there there's more of them that are scattered around the bench here and everything like that so those are way off now keep in mind that no fourth band or anything is means that these are all 20 tolerance so you know depending on its application if this was 55k it would be okay in some applications but whenever there's current passing through this you know and let's say you know supplying a screen section or something like that in a radio where there is a bit of current demand on it if it's supposed to be 47k ohms it should be replaced with something close if you lower the screen voltage on certain stages you'll also lower the sensitivity of the receiver and of course you know when you have resistors like this in the wrong area that are you know a lot higher in value let's put it that way that definitely needs to be changed as well because you know there's going to be quite a bit of voltage drop across that resistor then of course again the receiver sensitivity is going to be affected again especially if it's powering up the screens in the radio receiver or say it's in line with a a transformer that runs to a plate of one of the vacuum tubes something like that there'll be a lot more drop across this than there would be a 560 ohm resistor here's the bottom side of the chassis with all of the replaced components and as you can see they are everywhere all of these yellow devices are all brand new capacitors these are all brand new caps over here over here all of these electrolytics you can see the resistors that have been changed this is that one that got really hot and there's the 47k ohm resistor over here that was bad another 560 ohm here all the caps these are lots of electrolytic caps have been reinstalled they're all over the place these are the new caps that are across that 10k filter in the audio section there's more of these under here i had to remove this little tar filled transformer tar-coated transformer just uh the amount of work that's gone into the bottom side of this thing is very incredible the known death capacitor that used to be here is now replaced by these two components right here in fact i forgot to actually show you how bad that cap is it's over here maybe we'll revisit that here in just a little bit this is the death cap so it is very leaky so these are the x1 y2 rated caps across the line there i left the original line cord in because it's flawless the original cloth cord is soft and it's absolutely flawless now this uh this line cord is not to be confused with a curtain burner this is not a curtain burner line cord this is a you know just a it has solid wire in it you'll hear the term curtain burner uh what that is is a resistive line cord so the actual line cord of the radio receiver itself is a resistor and that was used in some of the early series sets to uh you know to create a drop across the line cord so that the you know the tube filaments and the radio gets the you know the the correct supply so again those resistive line cords are known as curtain burners now they look a lot like this but this is a standard line cord it's just you know standard copper wire in this so no problems there and again it's just it's flawless like the line code's not even a nick in it it looks you know completely fine and it's soft and pliable and flexible this is kind of nice to leave that on there because again it you know just maintains the original view of the radio on the outside so that's really good uh what else can i tell you about this these are these made in canada caps here that are just absolutely fine there's no problems with those and zoom on into that you can kind of see that so made in canada right there those ones seem to be okay now mind you a lot of the waxies were made in canada as well the uh the stromberg carlson ones were made in canada and of course anything you see made in canada these things are just horribly leaky so these are really really bad so um the micas are okay the paper and foil caps are the exact opposite so those are very very bad so lots of work done under here uh the filter caps that were in here have been replaced by these modern rubicon capacitors they're very uh very very good capacitors put it that way oh this is the resistor on the back that often fails that resistor i was telling you about that they don't give you any ratings for in the parts list or anything so this is adhering as you can see i've actually drawn in it's on a bit of an angle here because the way the radio is sitting but you can see i've actually just written down or drawn in the resistors where they go and put their values there right on that little strip you can see on the back side here i've taken a piece of that basically it's thermally conductive silicone it's designed for putting semiconductors against heatsinks and transferring the heat to the heatsink so it's resistive and i've also put that underneath here what happens is over time this plastic body of this resistor or the compound that they're using at any rate shrinks up a little bit and the bracket gets loose so by putting this underneath here it acts as almost like a cushion and in the tight spots it's very tight and it also you know it can expand into the areas that aren't so incredibly tight so it makes nice thermal conductivity all the way across the entire resistor body to the back and uh you know it keeps everything nice and cool so that's just something that i normally do and there's no heat sink compound or anything on it it's just you know that piece of heat transfer silicon underneath here and it's just it's tight on there like it just you know it's really tight so that'll keep that in very good condition if this isn't bad and you replace all the caps in here chances are this will not go bad it's just the capacitors that destroy these things sometimes i've seen holes burnt right in these things and what happens a lot of the time too they get so hot in one area that it charge the area in that area becomes conductive and then the actual resistor from the b plus section it's it makes somewhat of its own resistor because the the material has gone conductive to the chassis and it just makes everything all that much worse so they burn holes in them and everything like that so this is a nice barrier between that and the chassis as well on that one side so it's just a win-win situation doing that with these with these resistors here that is pretty much it that's all that's done here and um you know on the bottom side at any rate i haven't cleaned the band switches yet and just still spray the switches with contact cleaner and i will do that and uh the next step after that is to basically turn the thing on and see if it works see what happens oh one thing i didn't do either is i didn't check the little resistor where the uh where the eye tube is why don't we do that right now i don't know if you can see that get that right into the uh shot there let's see i'll grab a screwdriver here open this up and let's see what it is too big let's see where is the correct size that is a little small but it'll work okay so these just usually pop open just pry them up so a little bit of area around the side there you gotta be careful you don't want to break anything see there's a little index here as well so when you put it back together you want to put it back together so that index lines up with that there it is i can just pop that up with my fingers nope that is pretty tight that's pretty tight all right see if we can get behind the second layer here that should give me a little bit of leverage there it is okay there is that hiding resistor that's one meg ohms again body and dot brown one end is black is zero and then green is five zeros that's one million ohms okay so let's see if this is going to be okay from across the lab because i wasn't expecting on doing this let's see what happens does it need to get replaced or not turn this on just lay that in there get a bit of the glare off that okay see what happens that pin to this pin 1.55 not good that needs to get changed so 1 million 500 000 ohms so that's already halfway to another meg so that needs to go so there you go so if you ever have an itube that's not as sensitive as it should be you definitely want to change this resistor and as you can see this resistor needs to get changed again it's you know halfway to another mega ohm again so 1.5 meg ohms is way too high this should be one meg in some cases even just a little bit lower so i'll change that out and i'll go grab the speaker i'll flip the chassis over and we'll see if the thing receives anything all right place your bets what do you think is going to happen so you think this thing's going to work or do you think we're going to have some magic smoke hopefully not so before i did anything here i put two knobs on these two controls here that are a little bit hard to turn uh this one here is the if bandwidth and when that little arm comes over to move those two slugs up and down inside there it does get a little bit rough to turn and of course this one here is the band switch and it has that little ratcheting effect so i put two just junk knobs on here and the other two are just plain i can just twist these around with my hands i stuff the eyeball back in the top here hopefully that'll stay in there just held by this springs loosely and um yeah hopefully it's gonna look okay i think it is i don't know let's find out stay i might have to twist it around i don't know if the where the angle is the shadow angle is rakes haven't turned the thing on yet okay so this is plugged in my isolation transformer and current limited variax apply and i'm ready to go so i just want to make sure that the volume is down it is as you can see here the little volume moves up and down i want to make sure everything is just down before anything happens okay so here we go it's on that means that this switch is definitely on look at that all right so just wait till the tubes warm up aha i see a green glow that's a good sign so it does have b plus the rectifier in the back here is working that's washing out a bit because that's a very bright eye so i'm just going to turn that around until it looks like it's somewhat supposed to be there like that so it's just loosely in in place if i shine a light on the face here it won't wash out so bad you can see the eye a little bit better but uh okay so i'll try and get that down here so it's not totally ruining the look of the face of the radio there okay i can already hear radio stations happening here so uh this is the volume so you can turn this up so if they wow not much eye action happening here [Music] wow lots of bass so that's with the iaf bandwidth [Music] down at the bottom here let's find something here geeky breakdown so what i'll do is i'll turn this up here actually a lot of trouble come in winterizing yeah [Music] because in 30 states [Music] wow so it's it's really really sensitive not bad and it sounds so full amazing the bass this thing is rattling this speaker down here so the 6l6s are driving that speaker very nice so let's try another band uh let's see this one here looks like the switch or the bulb might be not all that great get that out of the way this is a little bit brighter so let's see if we have the wwv at five megs look at that there's no no rf alignment or oscillator or anything here [Music] that's the time signal at five so this band goes down to 1.7 so i can get the 2.5 in here as well let's see how close it is to 2.5 ah you think you're so so slick radio let's see if you come in at 2.5 okay so here it is 2.5 okay this is ridiculous this thing hasn't even had an alignment that's the 2.5 megahertz time signal okay so this is a 5.6 to 18 so let's see if we can hear anything at 10. no this is 10 right here so chances are i'm going to hear my own oscillator because i have a 10 megahertz standard in here so probably hear that there it is wow i'm gonna get 15. that portion of the band is out right now wow [Music] lots of bass in that okay so let's go down to i guess the beacon band roll up here that's a beacon right there [Music] wow wow well the uh oscillator is pretty close the oscillator itself on this thing is pretty close so obviously the person in the past this wouldn't be the original alignment i'm sure has done an okay job yeah i would i would be very interested in the iaf knowing what's going on with it because i noticed that when the iaf bandwidth is narrow it takes a lot to to cause the eye to deflect in order to um uh you know have a full deflection so that the eye comes together the two halves come together on a strong signal it doesn't seem to do that with the bandwidth very very tight like this so i don't know if you can see that in there i'll just get the light off and kind of see that see how this moves up and down here so with the i have bandwidth they say low fidelity low so they band with this very tight the um the eye itself is has a rough time deflecting so i don't know if that's an if issue or something like that we'll find that out so if i go to uh broadcast band here so this is the bandwidth again let's see some volume [Music] so you can see the eye doesn't really want to move all that much whereas if i uh [Music] it's more sensitive when it's wide than it is narrow which is kind of interesting so that might indicate that the iaf is definitely out of tune and of course the rf section in here might not be as sensitive as it should be as well so that would you know cause this to be like this now this has you know two if amplifiers right in three if transformers and the reason that it has the extra if transformer is because when you broaden the if bandwidth of course you lose sensitivity well in this case the sensitivity seems to be going up as we broaden the if bandwidth so the if just might be really out of tune so i'll get this thing attached to a spectrum analyzer and we'll see exactly how things are so i have to tune these little adjustments here there's an adjustment here an adjustment at the top and then there's one at this one here and one down here and then there's another if transformer as well so these little uh little adjustments here are what i'm gonna be twisting let's see actually just for curiosity's sake if these are live so let's see i'll grab my volt meter here and let's see if these uh are live to the case sometimes they i have b plus on them so i'll turn this on to here i'll put this up here for a moment very carefully let's see if i touch the chassis and this no they're not live on this that one isn't anyways so that's a good thing uh i warn people about this a lot some radio receivers the actual adjustments in the if transformers are live they have full b plus on them so if you have a metal screwdriver which you can turn these with just a standard metal screwdriver if you turn these with a with a standard metal screwdriver and if they were live and you slipped and touched the case i don't know if you remember the game operation something like that so you know this thing will end up you know shorting to the case and you can damage the iaf transformers so you got to be careful around devices like that these here aren't live so it's kind of nice so putting a screwdriver in is not going to be too big of a deal now using a metal screwdriver in all cases is not possible especially whenever you're dealing with powdered iron slugs these are just capacitors and you know this obviously are attached you know to the either the chassis or whatever so the magnetism of the screwdriver of a metal screwdriver in there is not going to affect these now a lot of the times again if you're going to be adjusting these things and you can use a metal screwdriver in the capacitors as long as it's insulated and you know it's not live it's the better thing to do because it you'll break your tuning tools in these these are you know just big screws screwed into a capacitor here i if i had one of these caps out i would show you it's just a you know a threaded big threaded screw that tightens some plates together inside of a cap here so normal tuning tools will get absolutely destroyed if you try to twist these because normally these are very tight so again it's all about balance use a normal insulated screwdriver where possible and then you know save your tuning tools for what they're actually needed for when you're dealing with powdered iron slugs and things like that for those of you that are interested in knowing how i attach my spectrum analyzer to a radio receiver to do a sweep of the if section here it is this is also valid if you want to attach just a standard sweep up to this like using an oscilloscope and a sweep generator this is the way that you do it so first of all you can see that we have the modulator tube here which is just another name for mixer tube and we have two input grids on this tube here now normally when a tube symbol like this is drawn they have a little cap on the side indicating a cap but they haven't done that on this schematic for all of these tubes that have caps so what i've done is i've just drawn that in here so the rf runs through the rf amplifier through these coils here and then up in this line into the cap and that's the line that i'm going to be feeding the signal from my tracking generator of my spectrum analyzer so there's a signal that comes out of my spectrum analyzer all right so the spectrum analyzer is running to the input line here that's what san is so the tracking generator puts a signal onto this line and i want to put that signal into here now i'm going to leave the oscillator running while i'm doing this alignment and i'm also going to lightly couple my spectrum analyzer into this circuit so when i'm attaching the signal into this grid line here i'm not going to directly couple the output right to the cap i'm going to clip the signal lead to the insulation of the wire running to the cap and i'm going to very lightly capacitively couple into that grid now the trick or the key to a successful alignment is to make sure that your test equipment remains invisible to the device under test if for any way shape or form you heavily couple into a very sensitive tube like this or section like this what you're going to do is you're going to drag your own alignment with the test equipment and what you'll find yourself doing is you're going to align the if section and you're going to compensate for the mistake of heavy coupling you definitely don't want to do that that is the difference between a good and a bad if alignment now the trick to the whole thing is is that when you're doing this if you heavily couple in and you're say compensating for that by tuning these iaf transformers when you take your test equipment off you don't know that you've heavily coupled in the moment that you disconnect your test equipment from this your if alignment changes because the capacitance and inductance added by your spectrum analyzer the way you've coupled it in is now removed and that changes the way the iaf looks so very important to remember whenever you're dealing with an if section and anything that's as sensitive as this especially this line right here you need to extremely lightly couple in now what i've done is i've created some little boxes here i've released this on youtube i believe it's under a spectrum analyzer protection device you can look in my list of videos and you'll see how these are built it's right here it's released on youtube at any rate my spectrum analyzer uses these boxes in line with the input and the output so output of my spectrum analyzer being the tracking generator and the input of my spectrum analyzer being the one meg ohm input of my 3585b so what this does is this protects the input this one here protects the input of my spectrum analyzer so what happens is there's a limiting network in here with some diodes and there's a whole bunch of capacitors in here that allow me to effectively keep everything flat during the if frequency so the boxes are flat within the if range and it is a very tight range that these are flat in but it allows me to protect the front end of my analyzer so if i was to say for example accidentally touch this to some high voltage i'm not going to take out the front end of my spectrum analyzer if you burn out this front end of a spectrum analyzer it's not like burning out the front end of an oscilloscope if you burn out the front end of a spectrum analyzer you're going to have a very bad day so you don't want to do that so i'm very very cautious around the inputs and even the tracking generator output of my spectrum analyzer there's another box like this that attaches to the spectrum analyzer output or the tracking generator and it's this it just says 50 ohms and high z it looks exactly the same as this so it just protects the the uh the inputs and the outputs and it's also an attenuation network in here so that i can properly tune these stages now these boxes are purpose-driven or purpose-built and again you can check out how i've built these things right here on youtube just look under my list of videos now i haven't released the circuit boards or anything at this point yet and i guess i should because i get asked for this all the time again i have another email today about you know putting these things out so i think i'm going to do that so i'll probably add the files to patreon as well so if you want to build these things yourself you can put some of these things together so what i do again is i clip the signal lead just to the insulation of the wire that goes to the cap and then of course the common just attaches to the chassis and that'll feed signal into here all right and then what will happen is by the time it gets through the if amplifier into this stage right here this is where i pick the signal back off and this goes back into the input of my spectrum analyzer now this goes to the one meg ohm input of my 35 85 b and i'm clipping it directly to the insulation again on the detector lead right here this is a relatively high impedance point in this radio receiver and that is very easy to drag so again with the isolation and attenuation of this box right here this is the actual box that will be attached to that i will just clip this right to the insulation of the lead and this will clip right to the chassis and that will pick up the signal and allow me to align this without dragging anything that will give you the best alignment possible so i'll get this all hooked up and we'll take a look at the spectrum analyzer screen and let's see how close or how far off the if alignment actually is all right let's see where the iaf is in this radio receiver let's see if it's close or if it's in outer space so we know that the center frequency of the if for this radio receiver is 465 kilohertz since this is a high fidelity radio receiver i'm going to want a span of about 20 kilohertz i'm going to want to see 20 kilohertz worth of width so that means that if the center frequency is at 465 kilohertz my start frequency is going to have to be 10 down from that which just happens to be 455 kilohertz my stop frequency is going to need to be 10 up from 465 so that'll be 475 kilohertz so i'll set that up right now so the start frequency will be 455 kilohertz the stop frequency will be 475 kilohertz and that puts the center right at 465. so i'll just leave everything the way it is right now and i'll turn on the radio receiver and let's see what happens i'll have to make some other adjustments here let's just see where we're at i also need to put this to the one meg ohm input because that's what i'm on right now there we go well already i can see that i'm way off so if i move the marker around you can see a little marker right in the center here if i move that around you can see this is the peak right here and that's where the center of the if is right now so we're right around 470 kilohertz that's pretty far off so what i'll do is i will adjust the db per division here 10 is a little bit you know well it's a little bit too much so i'll bump it down to say five just to start off here so the db per division 5 db that looks a little bit better now in order to find out where this actually is or to get as close as we can what i'll do is i'll just press signal track here for a second that'll bump everything to the center of the screen and then of course it'll keep the span the same so i'll just go signal track and i'll shut that off so there we go the center frequency is right dead on 470 kilohertz look at that right there so it's five kilohertz high perfectly so that is way off so what i'm going to do now is i'll adjust the fidelity control on the front of the radio receiver and that should expand this so we should see this widen up this is on the narrowest setting right now whenever the if adjustments are done that needs to be done on the narrowest setting and then once the if is peaked up and everything's done you can kind of critique it on the widest setting to make sure everything just looks good and everything flows properly so what i'll do is i will widen this up so i'm moving the fidelity control right now and i can feel that little detent just starting to hit the cam right now so i'll keep turning and as you can see i'm getting that gain and i'll keep turning this i'll just stop this right about here all right so it stops hunting what i'll do is i'll zoom on into the screen and that'll give you a better idea of what's going on here right about there is nice and close pardon the shaky camera i'll just adjust the focus here and there we go so that's at its widest setting that's looking pretty messed up so what i'll do here is i will narrow this up again and as you can see it's shifting so you can see the peak is right in the center right there now as i now you'll notice that as i showed you earlier when i narrow the if bandwidth up the eye isn't working as well okay so this is the narrowest now you can see as i'm widening things up you see how that is rising on the screen it's going up right now as that's rising what's happening is the if section is becoming more sensitive you can see that amplitude is coming up now as i get to the top this is about the peak and if i look at the front that's about three quarters of the fidelity control so now if i keep going you can see that it comes down again at its widest setting that's at its widest setting right there and as you can see it's pretty wide so again i'll turn the the fidelity control back down here so narrows things up you can actually see it the peak is moving off center here as well and then as i bring it back you can see the peak it kind of squeaks towards the center of the screen and it gets to about the center right there but you can really see the gain reduction that's why the eye isn't working very well so narrowest and you can see you know keep in mind this is 5 db per division right so this is if you want to see that i can go here and look at this right now it's 4.26 right no like look at how much that's coming up right so the peak would be about what 29 millivolts from and that's from just coupling in right you know on the insulation of the lead so we're down at four and we can get all the way up to 29 millivolts just by moving the fidelity control okay so this huge gain reduction there so there's a lot of uh you know it's it's really out of alignment so what i'll do now is i'll this is the narrowest setting right here so what i'm going to do is i'll just put one of my screwdrivers you remember if you recall earlier i measured the capacitors on the front of those transformers to make sure that they're not live what i'm going to do is the one that i measured all right i'll put a screwdriver in there and i'll just give it a bit of a twist just that one let's see what happens okay so it's in there it's really hard to work around the the tripod here the the radio itself has got adjustments on the front side on the side and on the back of the radio which makes this extremely hard to do on camera not only that to get the spectrum analyzer in the shot that it's sitting right in front of the radio receiver right now so what i'm going to do is i'm going to make an entire i think i should probably make an entire series on on tuning radio receivers doing the if sections and i'll have to create some you know other bracketry to hold cameras and i'll i'll go through that the entire tuning procedure unfortunately in order for me to completely tune this up i'm going to need to do this off camera the camera will have to be right out of the way and i'll have to be moving the radio chassis around in circles in order to adjust this thing it's just the way that they've set everything up some of them on the are on the rear and the tubes are in the way so move everything around okay so here we go i'm going to move that bottom capacitor you can see i'm moving the gain around and now you can see i'm actually shifting the center so what i want to do first of all is tune for the maximum at 465 so i can move this here it actually shifted it in the right direction so right about there so if i move the marker over see i'm about 468 now you see how much that shifted it so i'll move the capacitor in the top side of that and let's see what happens when i do that all right i can get my screwdriver in there this one's almost behind the dial glass this is a okay so give this a bit of a twist wow look at you see look at the amplitude coming up so right now by doing this as you can see it rising on the screen look at that that's sensitivity that's receiver sensitivity that you see happening right there lots of sensitivity added just by moving this around so right about there is its maximum sensitivity at at about 468. so you can see just by tuning those two capacitors how much this is already improved i've actually shifted this closer to where it's supposed to be at 465 and the sensitivity has come right up just by tuning two of those capacitors just two of them and there's uh you know another two transformers so that's four more of these that i get to tune in order to get bring this up so it's way out you can see that it's absolutely way out so when this is done the eye should work very good and i should get a very nice even spread on the on the iaf when i'm done so chances are it'll probably have a stage curtain effect so you get the the double hump kind of happening on here and once i've got this all perfected i will come back and i'll show you what i've done and i'll explain it uh to give you an idea of usually how long it takes to do an alignment like this you're looking at in order to perfect everything to make it look as even and you know to to get the best results possible it usually takes me about an hour or an hour and a half to do this and that's just moving back and forth between capacitors and just making sure that everything is right where it should be and of course you want it to look just as good when you're widening things up like this you can see it doesn't look too bad there you can see the double hump right here right but that's just you know that's nowhere near the end of the fidelity control that's the end of the fidelity control okay so you can see that it's starting to look a little bit more like it should and that's just by tuning those two capacitors so you get the stage curtain effect the double hump happening here so again i'll get all of this done and i'll show you exactly how this should look and then will be on to the rf and oscillator in antenna section tuning as well tuning the if section in the stromberg carlson took about an hour and a half and that is an hour and a half of me moving around those six variable capacitors in those three if transformers now i have to tell you that getting the iaf to work the way that you're going to see it here on the screen without using a visual means would be absolutely impossible with this receiver i'm telling you if i look at one of those variable capacitors out of the corner of my eye this pattern that you see on the screen will change dramatically that's really how sensitive it is it's so sensitive in fact these radio receivers sounded fantastic when they rolled off the factory floor i'm absolutely sure but the moment that somebody changed one of those iaf tubes or even the detector tube this pattern would just change you wouldn't have that same quality of sound that you would have had when this thing came from the factory i'll give you an example of that here in just a moment so you'll see that the center of the screen is exactly at 465 kilohertz now what i'm going to do is i'm going to widen up the if bandwidth and you're going to start to see that stage curtain effect now the whole trick of making these if alignments work the way they should is to keep that double hump falling and rising evenly so the stage curtain effect those two bumps you're going to see on each side they need to fall and rise evenly as you're moving around the variable if bandwidth so as those two slugs are moving up and down inside those two if transformers they need to basically work with each other correctly in order to get the sound all right so i'll give you an example here all right so i'm coming right to where this little detent is now touching the cam to where it's going to start moving those slugs so here we go now keep in mind that this is now at 2 db per division i had it at 5 db before but at 2 db it's you can see much more detail here okay so now you can see how it's widening up okay now you can see how i'm getting the stage curtain effect you see how we have those two bumps on each side you see how they're forming evenly that is a very difficult task to achieve because you'll get a bump on one side and it'll maintain you know a flat mark on the other side here so what i'll do is i'll move this down to its widest if bandwidth and as you can see they fall evenly and as i raise this they rise evenly and then they form the perfect bell curve in the center and then as we come to our narrowest bandwidth you can see the amplitude dropping just a little bit now that's absolutely normal right you keep in mind we're also dealing with only 2 db per division here so what you're seeing is very very minuscule so making this happen just like you see right here and then falling evenly like this is the result of about an hour and a half of tuning that's going back and forth between all of those capacitors and making sure that i maintain the 465 center and then i have those two bumps forming on either side now this is the best it's going to get you'll see right at the center right at the the very center of the dip here i'll just move the marker around you'll see right at the very center here you can see the little marker moving around there so you can see that the center is off really just into the hertz right at the bottom right so absolutely fantastic for an if section that was designed in the 30s in fact this is really quite amazing how well stromberg carlson put this together so what i'll do is i'll give you an example if i just just i'm telling you touch i'll just move this back to the center here again so it's right at the center if i absolutely just if i just push on one of those capacitors with a screwdriver watch what happens to the pattern here okay so let's get over here and i'll put a capacitor or a screwdriver in the capacitor and we'll just press on it see that now if i was to give this a twist of a hair's width we'll say maybe a millimeter look at that pattern the pattern is immediately destroyed we're talking moving that hair's width all right so i'll adjust the if here so you can see what's happening so you can see it forms somewhat even at the center there and comes back down but then once we start to widen it up we get one bump that's way off to one side so our our peak sensitivity will be off to one side of the i f and as you can see that's just really in outer space right now that's by moving just one of those six capacitors a hairs width so you can get an idea of how long it took to actually figure out how to make everything track and uh you know just have a good pattern here so i'll put this back in here and i'll try and get this adjusted perfectly again and i'll probably have to spend some time with this to get that right where it needs to be again just leave it there for now and i will move this around so we'll see this rise that's very close and it forms right at the center and that's the narrowest bandwidth right there so as i say doing this by just peaking method or using a vtvm or something like that would be impossible it would be absolutely impossible to get what this is doing right here so this radio receiver with that iaf that you see there will sound fantastic it will sound like an fm radio when it's wide so what i'll do here is since we're our narrowest position here what i'll do is uh let's calculate to see how wide the if actually is so i'll just make sure that that's at its narrowest point it is so i'll adjust the reference volts here and just bring this up to the top line so we'll go here that's pretty close so if we go 24.5 and that's 21. so let's see uh we'll say 23.5 let's try that 23.5 millivolts that's a little bit too high let's go 20 24. go reference volts 24 millivolts and that's very close to the top line there okay so what i'll do is i'll turn on the display line and i'll move the display line right up to the top so if you look here you'll see that this comes to zero db right at the top line there okay so since this is 2 db per box down i need to go down three boxes all right so i'll move this down three boxes and as you can see right it's you know minus six db right there and this is where they normally measure the if width okay so i'll go back to the marker and i'll move the marker off to one side i'll put it right at that line okay now we're at 467.08 all right so i'll get my calculator here so 467.08 and then we go take away so i'll go to the other side now 462.92 for 62.92 equals so we're dealing with 4.16 kilohertz of bandwidth not bad that's pretty narrow so it's very decent for communications quality stuff so that's going to allow us to really narrow in on frequencies that have you know other frequencies very close to them so we can really just get rid of all of the adjacent frequency noise so it's pretty decent not too bad and that's at six down usually i measure them at three down right because six is actually being kind of generous they were always kind of generous doing that but we'll just stick with the six because that's usually where these companies measured them okay so 4.16 kilohertz wide in the narrowest position so now let's go to the widest position and see what happens here so i'll have to probably bring this down to center screen here so reference volts bring that down to about here and i'll bring this back up so we can adjust this here in a moment okay so let's bump that controller let's go here so we're 15.1 and 17 so let's try 16 16 that's pretty close close enough all right all right so we're still at the 6 db down point you see the display line here is still at the 6 db down so if i go to display line you'll see you see minus 6 db right here that this line again three boxes down right 2 db per box all right so what i'll do is i will roll the marker back over here all right didn't i bump the display line it doesn't matter i'm using the uh the graticule anyways so go back to the marker so right there we're at 475.6 okay so we'll go 475.6 take away over the other side now 454 560 in fact i might be able to move that down just a touch right there so 454 let's see get this as accurate as possible right about there 454 560. all right take away 454.56 equals 21.04 kilohertz wide pretty fantastic for an high f section so go divided by 2 equals 10.52 okay so this is 520 cycles above their audio cutoff filter that they've designed on the underside of the chassis can you say stromberg carlson did their homework what a fantastic job we're only 520 cycles above right so it's 10.52 each side of the center this radio receiver will sound absolutely fantastic so there you have it that's how the iaf should look in one of these radio receivers keep in mind if you're ever going to align something like this you need to make sure that these things fall and rise at the same time you want to maintain symmetry as close as you can to their design and again you can see that the center is out just a touch but it's in the hertz here if we move the this right here see a little marker here technically that would probably be the dip right about there you know so not a big deal not a big deal at all it's so close for i have transformers designed in the 30s this is ridiculously fantastic so anyways let's get on to the other portions of the alignment i'm going to perform the antenna and rf alignment in this radio receiver i'm not even going to bother with the oscillator adjustment because the frequencies as displayed earlier are spot on and it's yeah this thing is so incredibly close i've actually never come across a receiver that is this close without me doing an actual an alignment on the oscillator section so these are the oscillator adjustments here that don't need to be touched this is the rf adjustment here you see the rf written there this is the rf adjustment so that in that box there is the rf coil and these are the tuning capacitors and this is the antenna adjustment right here so i will adjust this one here and this one right here for the broadcast band so i have my signal generator set to 1500 am or 1.5 megahertz and i'm at 100 microvolts so i'll just move the dial to 1.5 megahertz here 1700 that's so ridiculously close listen to that it's it's spot on 1500. and that's with the if with narrow it's right on the line again i've never come across a receiver that's ever hit the bench that's been so in tune that way it's actually kind of surprising so now that the if section is done we can use the eye itself as a tuning aid so i'll just tune this off frequency here again and i'll show you that the eye is functioning correctly and shield some of the light from it there maybe a little bit okay there it is so i can use this as a tuning aid i don't even need to hook up a vtvm or anything like that now the capacitor that's in this circuit here the time constant for this is a little bit slower than i would like it to be i'm almost tempted to modify that in the design i'd like this to respond a little quicker but that's okay okay so what i'm going to do is adjust the antenna section here and just tune for a peek so i want this to come as close together as possible and i have a feeling this is probably spot on as well okay so let's see where we are oh now i can use a bit of a peak right there and then i go over to the rf which is right here i don't think i can aim for this without tipping the chassis here because it's right underneath the camera so we'll just move this like so and put this in there it's a really big chassis really awkward to work with here on camera okay and i'll tune the rf section so again we're tuning for maximum closure right there the thing is really spot on now if i was to touch the oscillator adjustment right here it would just tune this thing off frequency that adjusts the dial tracking so i definitely want to be touching that because when i say this thing is spot on it is spot on this eye tube here is looking okay but it might be a little bit tired i think i might just grab another eye tube here it's nice and bright but doesn't seem as sensitive as it should be so give me a second here let's unplug the eye tube and i have another one here across the lab okay so here's a brand new one this is a jn type one joint army and navy 6e5 so this is gonna be a really nice tube here plug that in let's see if that's any better this is brand new so it might take a few moments to come to life so to say let's get rid of some of the light off of that there yeah it's definitely closer together i'll just move this off frequency here that's definitely more sensitive and it's quite a bit brighter as well so i think i'll leave this one in there that's very very bright very nice eye tube there so so now what i'll do is i just have to go to the other bands do the exact same thing just basically rotate the band switch here like that and then go to the next band and tune it so i'll start at the bottom i'll start with band x and that's these adjustments here in these cans here i'll see if i can show this to you well this thing falling off the bench this ridiculously awkward thing to work with that's tuning these right here and then i just have the rest of them to tune which are here so very simple alignment everything as i say the whole oscillator section here seems to be right on frequency so the person that was in here last really did a good job in aligning the rf and the antenna in the oscillator section but um wow that iaf was in outer space so everything good except the iaf really was aligned okay by the previous technician another portion of this radio receiver that has been most likely detuned over time and never retuned properly again is this 10 kilohertz audio cutoff so there's a little filter network down here there's an inductor and a capacitor across it that's designed to cut off the audio after 10 kilohertz so this is between the last audio amplifier and the grids of the 6l6s now there are no instructions on how to adjust this in the alignment procedure so that's something that was done at the factory and i guess they just expected you to leave it alone i would imagine back way back when stromberg carlson had a sweep setup for the audio section in this as well so i'm going to use my stanford research sr780 to sweep the audio section and i will make that adjustment so that we can cut that audio off after 10 kilohertz i'll get that set up and i'll be right back the stanford research sr 780 is attached to the radio receiver so the source output or the signal coming out of the stanford research sr 780 is fed to the wiper of the volume control and the input of the sr-780 so the signal going back into the analyzer is just picked right off the voice coil of the speaker so i have the sweep set from eight kilohertz to 12 kilohertz and that should get us within the range of this adjustment here and we should be looking for a dip or a null around 10 kilohertz so i've got the marker set to 10.02 kilohertz the reason it's sitting at point zero two is just because of the number of points i have here if i up the number of points it'll sweep slower and the slower sweep is painful to work with so we'll just leave it here 10.02 is close enough turn on the radio receiver and wait for the tubes to warm up and the analyzer is set to auto range so it should pick up where we need to be here let's see where this thing is sitting no you see something on the screen here so we can see the the dip or the null is actually quite early so let's see where it's sitting here sitting around 8.5 kilohertz that's no good it's supposed to be at 10. so i need to move that dip over to this line over here so what i'm going to do is insert my screwdriver into that adjustment that i just showed you and i'll give it a bit of a twist okay see which way are we going nope that's the other way you don't want to go that way so let's try the other direction now i have to wait for the analyzer to catch up because it's a slow sweep so we're going in the right direction that is a good sign and there is quite a bit of adjustment room here so that's good i'm just about there one more little tweak oh i passed it see if i can see how far i can actually go here whoa so you can see i've completely passed it so i'll back the control up until that dip is right in the middle of that line so every time the sweep goes past i give it just a bit of a turn so let's see how close we are here a little bit more a little bit more i'm just moving this control a hair and i think that's it right there that's looking pretty close so let's go let's up the number of points here so let's go let's try 500 enter and i can probably move the marker i think that's as close as i can get right there 10.003 it looks like it's spot on that is a slow sweep yep it's right in the dip the radio is all put back together let's cruise around the broadcast band and see how this thing sounds so hopefully the mic will pick this up i have it pointed towards me so it'll hear me but it is a really full sounding radio so let's get some volume here you can see as i'm turning the volume up it moves that little scale up over there it has this little red dot on one side which seems to be almost a perfect volume all the time so that's kind of interesting okay here we go [Music] government officials on the program you'll have the guess you need [Music] [Music] fidelity [Music] [Music] i'm [Music] very full like stations absolutely everywhere the radio itself turned out very nice i'll give you a view of the front of the radio here you can see the nice gold leaf and the grill there just it turned out really really nice i cleaned up the uh clean up the wood just a little bit basically really didn't need too much right so that worked out well so let's try another band here let's see uh go to the beacon band this is uh aircraft beacons down here so what i can do is zoom in just a little bit more actually no this lens is gonna allow me not to zoom so let's just give this a shot let's take a look give us some volume here there's another one here and that's right down at the bottom not a whole lot down around uh 145 kilo cycles that's way down at the bottom that's uh way below the if frequency of this receiver here so the it stops at about 360. this is 370 right here i think 360 was the last that's far enough away from the iaf so that uh yeah 360. so it's 360 there and uh the last would be 370 right about there so yeah it's uh way way way down there now they have police written here but i think that's for the next band up way way way back when so let's uh let's uh up the fidelity just a bit and um let's see here maybe i can find something to give you a better example of uh how the high fidelity really sounds on this problem is is that you need music to do that and we know how that works on youtube so let's see here if i can find just a station that has pretty clear [Music] and talking to great lengths to concoct commonalities however the alleged similarities as well as the terminology used to communicate them are clearly exaggerated isn't that fantastic that's full fidelity it sounds like the person is sitting right in front of me it's just incredible so i'll just go to the next range up here and let's see these ranges the higher you get in frequency at this time of the evening it's gets really quiet we'll see if i can find uh let's see if we can find the wwvb or wwv i should say the vb is down at 60 kilo cycles this the wwv should be a 2.5 at this time there it is i don't know if you see the action of the eye it's kind of uh blown out here let's see if i do this all right and i'll just stop now if you remember the if curve way back when we were doing the alignment you get a certain way through the fidelity it comes to a peak and then it comes back down again and you can really see that with the fidelity control even with just the noise so what i'll do is i'll bring this to the start okay so this is the start of where the cam is just touching the slugs now as i increase the fidelity control you'll see just from noise the actual eye will close so that's its peak right about there and then as i go to full fidelity it opens back up again just a little bit it's right about there it's full right there i don't know if you can see that very little change right but at any rate that shows you that you know if this is following what we've done in the iaf so very interesting it sounds the best right about there about three quarters the way up so anyways let's uh try and let's go to the other one that's five megahertz is the other time signal that's very strong so i don't know if you can see that that's going to defocus there it's pretty much closed so i'll go off frequency [Music] lots of noise i have this hooked up to a really large antenna so this wants to receive lots of stuff at this at this time of the evening here and uh this is uh you know this band is pretty active [Music] there is shortwave broadcast in here this is pretty much between the 80 meter ham band and above this is all quiet down in here oh there's some side band in the 80 meter band well somebody was there a moment ago and the upper band will be just pretty much quiet at this time see if we can see my oscillator at 10 megahertz here again [Music] there it is so that's my own standard here [Music] i [Music] is so there's a little bit of shortwave broadcast there as you can see at the lower end of the dial at the top here this comes to life during the day and this is uh this here will actually just uh bring you back to full brightness here so this comes to uh this comes to life during the day uh at the at the you know the top band here this is kind of you know middle to end of the day and in the morning and then of course this is a beacon band here which is you know going to be active most of the time at least with local beacons so all in all let's leave that here let's go back down to here and move this up to here so all in all like the radio itself is uh yeah it's working just absolutely fantastic out of most of the radial receivers that i have restored i honestly have to say the stromberg carlson is probably the most enjoyable to use really uh the fidelity control as you heard is um just makes am listening fantastic now you can't really use the fidelity control if they're stationed on station if they're very close together because the iaf just goes so wide that you you're kind of into the next frequency already so when stations are piling up you have to have this narrow and it really does narrow into the frequencies quite well when they're very close together so that that variable if width really does help tons of audio driving power it uh it gets quite uncomfortable after that dot this is the dot right here and as you can see i'm kind of raising my voice after that it just it just it gets absolutely crazy so those six l sixes are driving the speaker the difference of having that speaker sitting in this cabinet with the uh the acoustic labyrinth behind it is somewhat amazing uh the the bass frequencies the lows that come out of this radio receiver are absolutely astounding that the lows are just i don't know how to even describe it i was listening to some country music and just all sorts of different things on the am band here earlier just trying to find as much different music programming as it could and uh it sounds like fm really it does it uh the bass is just rumbles the place um if you have a chance to get one of these radio receivers if you find one of these stromberg carlson 145s i strongly suggest if the pricing is right pick it up and yeah put the time into it to restore it if you like listening to am and you like these old radio receivers this radio is nothing short of fantastic it really is basic courtesy in marriage yeah you know i'm thinking of that either husband or wife and i'll use the wife because i think it leans that direction most often where she doesn't feel connected any longer emotionally spiritually maybe even physically she's drawn into this conversation okay there's some things i need to do maybe it's the husband there's a better example of how this sounds with the microphone more optimally placed let's put it that way the only way to really appreciate the fidelity of this radio receiver is to just sit in front of it i realize in the last shot the audio is a little bit boomy but i was trying to get myself and the radio at the same time but unfortunately there's a lot of room echo in here and everything like that i just about left out the capacitor of doom here it is this is the capacitor of doom that came out of this radial so this is the factory device it is actually shown in their parts list is a little half circle on the side of the chassis and this is the thing it's clipped in a little hole here on the bottom of the uh of the chassis so it kind of runs through the side of the chassis and then they bent this tab up original device so let's see how bad the capacitor of death actually is so there's a lot of misunderstanding around the function and about the function of this particular device here so ac line cord decoupling and all sorts of things to do with rf and and emi and all sorts of things i'll get into the exact description of what these capacitors do their functions vary within different devices actually but you'll see the same kind of setup sometimes you'll only see one sometimes you'll see two sometimes you won't see any at all it just depends on the actual device itself that the death capacitor is in in this case it's an actual radio receiver so it's doing multiple things at any rate so what happens is this thing ends up failing so they short and what they do one side will short and if both sides short it'll take the fuse out but if one side shorts what it does is it'll take one side of the line cord and put it directly on the chassis so that's not a very safe situation is it so that'll uh that'll cause some issues the new replacements to these capacitors are these ones right here so this is known as an x1 y2 rated capacitor and they have all sorts of safety ratings on them and these are designed to fail in a safe manner i won't get into the failure points of these capacitors and get too deep into the caps here but at any rate this should be replaced with a very safe device if you're restoring radio receivers that have these caps it's an absolute must to get rid of these things you don't leave these behind like the previous people that have gone through this radio receiver so you definitely don't want anything like this to go bad so let's take a look at what's actually going on with this thing here so this can be directly the scale on this device can be directly converted into ohms so basically what this is going to do is it's going to look for the resistor that this thing is trying to turn into okay so this is a very sensitive device this thing will go up to 40 billion ohms in the forecast position to really look for any type of leakage any type of resistance that may be hiding in these capacitors due to just it degrading moisture aggression all sorts of different things again a very purpose-driven device so the first scale is red that's a really bad scale and then yellow and then it starts off at the yellow scale on the second scale and it works down and it becomes green at about 40 billion ohms all right 40 gig ohms if you prefer so let's see how actual bad this thing is first of all you know what let's test the new one okay so this is a brand new capacitor here okay so what i'll do is i'll just uh i can turn this on it'll read the resistance of my hands as i'm holding these things so i'll just have it in the test position to begin with it doesn't really matter so again it's a low voltage tester so you know there's no issues here whatsoever right so the first scale is red as you can see and when i'm holding these here i'll bring it up to the yellow scale to the top of the yellow scale is about a billion ohms okay and then if i short them together you'll see that that's a dead short so that's the start of the scale right there and then anything beyond this is about a mega ohm and it works its way up to one gig ohm the scale flips and it goes from one gig to 40 gig ohms all right so i'll put this on here so there it is okay it's on the test and as you can see it's comfortably going up to 40 billion ohms and beyond in the forecast position the forecast position on this thing is the most sensitive position there is and again if i just touch the boots of this very very lightly you can see that i'm discharging that cap at 40 billion ohms so it's reading my body resistance through a vinyl boot so it's reading the resistance of this boot of my entire body and then back to this boot here and the resistance again okay so you can see that just by lightly holding that so very sensitive device again it was designed to look for obscure issues so so here is the death cap okay so i'll put the positive lead there now don't be confused you can see a chassis ground symbol don't be confused by that this is an alternating current capacitor and it really doesn't matter these capacitors are not electrically polarized so it's in a shell and of course it's designed to be across an acl line so the polarity is flipping around all the time so let's test these out and see what we get all right this should be interesting keep that here make sure the boots don't touch anything so as you can see that's pretty bad so that's going to be just below 20 mega ohms so this next light up will be 20 meg ohms all right i'll grab this resistor here just to give you an example i got a bunch of them put together these are 20 mega ohms each all right so the 20 meg ohms should be the next light up here so very very bad so you can read you would actually be able to read this is so bad you could read that on a standard dmm okay this here goes way beyond a standard dmm so there you go so that's 20 meg ohms right there right across that one resistor and we're below 20 meg ohms with this so if i was to put this across a dmm it's going to read very close to you know i'd say between 10 and 15 meg ohms okay so you can see that you know this capacitor is really bad let's test the other one so we tested one here i think it might have been that one this is the one that we've tested here so it'll creep up to just below 20 mega ohms okay and let's test this one here this one here is open oh no it isn't so this one's on the verge of shorting out this would have been the side that would have most likely caused very bad issues you can see this thing it's in the red scale and it doesn't know what it's doing look at that so right now if this was attached to a line cord it would be inside it would be shorting out it's sparking it would be sparking and doing all sorts of things inside there because it's intermittent and as you can see it's intermittent in the red scale so it's really really bad so this would have been the side that caused the issues so now depending on what side you plug this into the wall okay because remember this is putting low voltage across this and this is seeing this issue right now so the line cord that's that's on this thing isn't polarized so you can plug it in this way or plug it in this way so there's a really good chance that you would have put the hot side on this and that would have been connected to the chassis and as you can see inside it's intermittent it's basically this would be you could say sparking inside right now or sizzling inside there right now and i can almost guarantee if this was plugged in the next time this was plugged in that would become a dead short so it would have attached the line cord to the chassis so how do you like that that was caught just in time this other side here seems to be pretty constant so this one here wasn't doing the same thing this one here is just showing a fixed resistance so this is that other side would have been the extremely dangerous side so crisis averted there so i just think somebody had worked on this thing and left this thing in there and that was on the verge of happening the chassis of this radio receiver was on the verge of becoming live and who knows if these would have actually showed it would have taken that fuse out right that little fuse would have gone away that's hard on things you know it's hard on the power switch and it's hard on all sorts of things so definite crisis averted right there big time at any rate if you're interested in building one of these things again this is on patreon with all the plans along with many other of my creations up there definitely check it out if you're enjoying my videos you can let me know by giving me a big thumbs up and hang around there'll be many more videos like this coming in the near future we'll be taking a look at vacuum tube and solid state electronic devices alike so if you haven't subscribed now would be a good time to do that as well if you're interested in taking your electronics knowledge to the next level and learning electronics in a very different and effective way and gaining access to many of my personal electronic inventions and designs you're definitely going to want to check out my ongoing electronics course on patreon i'll put the link just below the video's description under the show more tab and i'll also pin the link at the top of the comment section so if you click on the link it'll take you right there all right until next time take care bye for now you

Channel: Mr Carlson's Lab

Views: 336,495

Keywords: Radio repair, radio restoration, restoration video, repair video, learn electronics video, spectrum analyzer, oscilloscope, test equipment, tune a radio, tune a receiver, fix electronics, repair electronics

Id: GB37DyAQazw

Length: 136min 26sec (8186 seconds)

Published: Wed Dec 23 2020