Tiny Radio Restoration With Detailed Procedure!

hi everyone and welcome to another restoration at mr carlson's lab let's get started here's a cute looking little six transistor radio and it's a little carrying case with a carrying handle i guess i don't let anybody carry it like that but anyway very cute tube is here to give you a size reference how small this actually is so let's open this thing up together and see if it works and if not let's get it working most of the time they don't so let's see if we can get this case off of here i think actually pretty nice condition maybe like so look at that oh and a little schematic that is tiny man i wonder what they did to write that or shrunk it down or something that is very small i might have to change my lens so we can take a look at that zoom right on into that so it's in very nice condition schematic and all and look at the inside of the radial looks pretty original and it looks very very clean so it has a 9-volt battery and i will need to go get a 9-volt battery because i am opening this up and we're discovering this at the same time so i'll go grab a 9-volt battery and pop a 9-volt battery on this thing and see what happens and like magic a 9-volt battery appears alright so let's see what happens here no noise yet let's do that [Music] that's interesting it sounds like he's trying to receive it's just making horrible noises nothing's coming in oh no well it definitely definitely has uh some form of issue going on inside here so what we should do is diagnose that make it work again so i'll just get rid of this thing oh i'd also like to mention if you're interested in radios like this being repaired and restored and serviced and brought back to life these little types of radios in all sorts of shapes and sizes you might want to check out shango 066 his channel he does lots of these restorations and repairs and and resurrections i think he calls them and all sorts of things with these little types of radios russian radios and all sorts of you know very interesting little transistor units so what i'll do is i'll put shango's link just below the show more tab under the video's description and uh once this is done you can click on the show more tab open up that and then head over to shango 066's channel if you're interested in this kind of stuff he also does television and radio repairs and all sorts of interesting little things he does there so definitely check him out he's got a really interesting channel here we are a little bit closer to the action here that's very nicely put together very nicely put together some of these things are just absolutely thrown together these radios but this one here is actually uh pretty nice they spent some time in the design here which makes you really wonder back in the day when these things were coming out servicemen were still used to working on things with vacuum tubes in them like this look at the size of this thing right and when these things started to come out with these little metal cans that have got you know three legs on them and no heaters inside it really makes you wonder how many servicemen said look at the size of this thing this thing is teeny how am i ever going to work on this you know and then you compare that to now where you know resistors this size are now the size of a grain of pepper you know surface mount stuff you know size 0201 and things like that you don't have standard sizes in your cell phone and all that microprocessors with millions of these inside of course these are germanium but you know silicon transistors millions of them inside so how things have progressed even from this day this only has six transistors versus you know microprocessors again with millions of them inside pretty amazing right where we've come from these days at any rate let's get the circuit board out of here looks like it's uh stuck in there pretty good so it's flexing over here and it's pretty solid in here now if we look at the the front of the unit a lot of the times you have a little screw in the front of the dial right these little tuning capacitors here have got a screw in there but there's no way we can get to anything like that and if you look at the the how round this is the screw would probably be right about there right so i would imagine what they've probably done is slip this in like this so it's come down and pushed in like that and of course there's a piece of paper in here which is usually hiding stuff so let's see what this is i don't want to break this isn't so nice well there's a screw right there i'm wondering if there's another one over here ah this might tear i hope not well you know what i'm gonna do i'm you can see they it looks like they've even glued it to this area right here so i don't know if i'm going to be able to save this without this getting damaged i could very safely cut this and that would probably you know save any kind of you know save me from tearing it at least but if there's a screw here there's a really good chance there's a screw right about here so i'll just lift this up carefully and take a peek is there it's coming coming up let's see some glue or something here no it doesn't look like there is a screw on that other side so i'll undo this let's just do this first and see where this gets us a little screw everything that's an interesting looking little screw all right so let's see what this does now does this do anything for us that's helping out i mean there's something hidden on this underside under here it still seems pretty tight over here i can't see these going you know because it looks like they're underneath the circuit board right if you look at the depth of the screws here it looks like they would be underneath the actual printed circuit board you see that so i can't see that holding the board in so i don't want to take those out unnecessarily so what i'll do is yeah you see that's flexing pretty good there so i'm thinking there still might be a screw hidden on this underside i really don't want to damage this and make sure the screwdriver blade is flat it's a pretty small screwdriver blade there nope hey maybe i can just bend that up we'll see how that goes bend that up like this so what's holding this in that is still pretty tight in there i don't think this is no that's not doing it either maybe they've just glued this in or maybe there's something hiding underneath one of these capacitors or something holding this in [Music] be very careful i don't stab that speaker it looks like it's trying to come out it might be glued possibly there it is there it is just stuck in there from years of years of being put in there it looks like i'm gonna need to desolder these two little little wires off the speaker to get this board out of here so i'll heat up my soldering iron get that happening and i'll be right back all right the iron is warm and i think i'll be able to get into here like so i'm doing this on camera and i'm behind this so hopefully this is gonna work out all right it did that worked out cute little wires about the size or maybe just a touch bigger than kynar but i'm pretty sure that this would very easily burn so i'm just gonna push this out of the way so that i don't burn this with my soldering iron you know the way about as much as i can and let's get this red one out of here i can see that green one is trying to get in there so i can burn it there it is okay let that cool off all right i think we can get this out of here now look at that that's really nice they did a nice job here and this they've little areas covering this with some form of just looks like tape it feels like vinyl and that's very nicely put together i don't think with this lens i can zoom any closer but uh there it is the bottom side they did a nice job to even clean the flux off the areas pretty well just a little bit down in here but this area over here looks really nice and clean again that's kind of abnormal for a lot of these radios a lot of these rays were just absolutely thrown together okay so now that that is like that i'm going to need to get some cables somewhere off to the side and two of the color yellow should do the job just fine and very carefully clip that there and this out of the way very carefully clip this over here not gonna hold it is so i can put this out of the way so now we have a speaker and i can have that ready to clip to these little wires here well to that wire that was once there i think oh no it's still a little bit left and then we can have some speaker action going on so it is howling and let's see if we can get this out of here so with this off to the side all the way like this i don't know if this is going to be indexed they usually are let's get rid of this right now see there's that screw that i'm talking about right here so that little screw is what hides underneath the front portion there so move this out of the way and i will put this right off to the side yet it is indexed so i don't need to worry about finding the spot to put that on all right so now we're in here like so and these two capacitors over here are probably troublemakers they look like they're 30 microfarad most all these capacitors are troublemakers look at the ends of these things you see the end of that and this one here it looks like it's almost swollen over the end so you know that these are probably toast so we can do is uh it looks like the radio is somewhat functional and it's trying to work so since this is actually trying to work that means that one of these isn't shorted if it were shorted we'd probably get nothing or you know close to nothing so what i can do is take something similar to this because these aren't going to be crucial these are most likely just for decoupling so i will soon get a 33 microfarad capacitor and what i'll do is i'll just touch it across this and what are these five micro farad this one here and this one's 30 and that one's 30. so lots of 30s and a 5. so what i'll do is i'll go get a 30 and i'll put it across here and we'll see what happens and we'll just work our way along i'm pretty sure that of course you know the electrolytics are most likely gone but it'd be interesting to find which one is actually causing the issues let's try that out very back all right i've found a 33 micro farad 50 volt capacitor on my other bench now it's a nishikon cap there it is so that should work again these are just bypass capacitors so it really won't matter i also have a 100 i think 25 here as well so whatever either or again not very important in this application as long as it stops the radio from doing what it's not supposed to do and that's what these two capacitors are here for they're just bypass caps now it looks like both of the positives of the capacitors are in this one eyelet here and it looks like the negative split off so one negative splits right off to the the negative battery terminal so basically the caps across the battery when you turn the switch on and the other one runs off here to another negative portion so the positives are tied together at the switch and then this runs off to another negative portion of the receiver which is split off into different sections here so those will be the two that we'll look at first because those are going to be the biggest culprits so what i'll do is i'll attach the speaker back up and let's see what happens here so this lead we'll just go to here i'll just attach it to the solder joint so i'm not going to pull on that little red wire this one i really don't have a choice so i'll attach this here like so and then again this is just this little speaker that's off to the side and attach this up here again and turn this on [Music] not much of a radio okay so let's see what happens if i add this 33 across this first one right here so this is basically just across the switch to the negative battery terminal hopefully this will reach i guess it really doesn't matter since the switch is closed i can attach it to that side as well so let's see i'll make this squeal a little bit [Music] so you can see it's already changing the pitch [Music] okay so we know that this capacitor is probably functioning somewhat so that would be the one of those capacitors on the top side so the other one runs from the positive to over here so the positive is running right down this trace here so i can basically jump it from this trace to this trace so let's try this make it squeal again sorry about the horrible noise but this is what the radio is doing okay so here we go [Music] look at that [Music] so that looks like that's solving it it's still got noise it's still got static in there very very low so what i'll do is let's turn this down for a moment you can put a tuning tool or something in that let's see if this will work let fit in there nope that's way too big how about this uh it one be enough to turn this is going to be enough to turn that no it's not turning it cram this down in there like so nope nothing wants to turn this because i think i can unthread that well what i'm trying to do here is i want to get something on the dial maybe i can just hold this and turn this at the same time let's see that yeah that'll work so i'll just do that so i'll hold this on here with one hand and i'll turn this with the other all right so let's turn this on [Music] it's hard to hold this all steady okay stay okay here we go it's trying to work it's definitely trying to work now that's full volume right now so obviously this thing definitely needs to be tuned up as well and i also notice that since this has been removed and i've been moving this around on the bench the static level has dropped out on the radio just a little bit so probably you know values are moving and of course this thing hasn't been handled in forever so one of the first things that should be done is that capacitor should be changed but before i change this capacitor in on the other side here let's um let's try an esr reading of that capacitor so i'll just grab the meter here this is going to be very bright and unfortunately the factory displays in these are very dim some people have modified these let's get the lights off this i've modified these uh esr meters and put brighter displays in them and i think i might do the same thing so turn this on there it's not doing too bad and i'll move the focus over to this so that it looks a little bit better i will short both of the probes here so i can zero them out hit zero on the bottom here as you can see so one capacitor is from here to here and the sr3 pointing not great but or it's at least it's functioning and the other one runs from here to here and as you can see that capacitor is definitely bad it's not it's right out of the range of the meter and that's the one that stopped the buzzing let's move the focus back over here so that's the one that stopped the buzzing when it went from this track to this track so definitely one of these capacitors here is open and it would be the leads might be crossing i think it's this one here this one here is the one in fact i can just double check that pretty sure it is nope that is not the one is this one this is the one that's the one right there tricky as they are overlapping each other so this is the faulty one right here and then this is the one that's somewhat good so before i go about swapping this out what's actually happening in this radio receiver to make it you know squeal and howl like that well let's take a look on an oscilloscope and i'll show you exactly what's going on all right i have the scope hooked up and i'll explain what's going on inside this radio receiver and why it's howling like this so i'll turn on the radio here i don't need to turn it on to where it squeals i can but just leave this down like so and what i'm going to do is i'm going to probe the last if right just by the detector all right in the vicinity at any rate and as you can see we're at 4.8 volts peaked peak something like that and the if right now is looking to be a little bit out 465 or something like that it's probably supposed to be 455 like pretty much all standard radio receivers by the time this thing was made now you're probably thinking to yourself well you know you see the if there and it's 4.8 volts peak to peak looks like it should be there right no there should be nothing there right now because we're not receiving a radio signal the only time we should actually see the amplitude of this rise and it actually display the iaf is when there's a radio station being received so what does that tell us well that tells us already that there's some sort of issue happening giving us a signal to make the if come up like this so chances are there's another oscillation happening or some form of harmonic going on in the background how can we prove this well if i move the dial around hear that it sounds like this thing i can even remove this it sounds like it's full of harmonic content hear that so basically as i'm moving this tuning capacitor i'm moving all sorts of different oscillations basically at the same time because there's just a lot of content happening in there now one of the things that can get very very tricky with this you can see that no matter where i move this it's still pretty much where no matter where i move the tuning you can see it's pretty much all there harmonic contents a little lower at that point right there as you can see it's pretty much all there now if i look at the actual oscillator itself which is at the top here see i might have to adjust the scope for this let's put this on here yeah i can just uh actually what i'll do is go here and i will go here so if i move the oscillator around it's looking pretty good right doesn't really look like there's too much wrong with that i'll just bump this up a little bit all right it's not looking too bad you can see a little bit happening right here that may be a clue as to what's going on you can see that oscillator looks relatively clean right that's from end to end i'm falling below the trigger here so i'll just hit millivolts here and make it a little bit larger so there you go so it looks relatively clean right but yet when we're down here you know like you can see the amplitude and slow that up just a little bit so there we go right so we still have all of this here now what i'm going to do is i will take that capacitor that's just nicely disappeared i don't know where it went uh here it is i can use the 100 as well doesn't really matter so what i'm going to do is i'm going to bridge this capacitor right to the affected area that stopped this thing from howling right where it howls right so i'll put this right down here right okay so if i clean this up what should happen here well this should obviously disappear we're not receiving a radio signal right so basically what i'm doing is i'm cleaning up the oscillator and all sorts of other portions of the radio receiver here right so here we go look at that let me get better connection here there we go and that's what we should see until we have a received radio signal now when we have our received radio signal we would start to see the amplitude of the if rise and start to see this and it would display the if frequency but right now what's happening is the scope is looking at some form of signal that's basically making the iaf you know give us an if signal right here so it looks as you can see right completely clean and then i remove this it's like this so there are harmonics and all bunch of stuff happening here in the oscillator section now as you can see on the scope it looked very clean right we had a very nice looking signal something like this right here now we can't really see all of that harmonic action unless we use a spectrum analyzer so what i'll do is i will set up the spectrum analyzer and we'll take a look at the oscillator and what i'll do is i'll put that capacitor across it and you'll see that harmonic content or a whole bunch of it at least just disappear all right let's take a look at what the oscillator looks like on a spectrum analyzer so i just have my oscilloscope probe attached to the one mega ohm input on my analyzer it's good enough for this display right here so try and get the cable out of the way a little bit alright so what i'll do is i will attach this to the oscillator and what you see on the spectrum analyzer is the fundamental so i'll just try and hold this here and point to the fundamental so that's the fundamental right there and this is all the unwanted garbage we don't want between this this is okay and this is okay here but all this stuff in the middle is the stuff that we don't want we want to get rid of that and all the stuff on this side over here as well okay so what i'll do is i'll put this capacitor here across that and watch what happens i can get a good connection [Music] look at that cleans up all that unwanted harmonic content and with the capacitor out look at that now it even gets more interesting when we take a look at the iaf look at this wow so what i'll do is i'll put this capacitor back in and watch what happens to the harmonic content look at that cleans it right up and without the capacitor wow [Music] so you can definitely see the importance for those two little capacitors on the top so now it's time to change those and put in some new capacitors in fact what i'm going to do is just change out all the electrolytics in here because well it's about that time right all the other ones are still working right we still get audio you can hear it making noise but it's time to freshen up the radio receiver and give it some new parts so i'll get that out of the way and we'll do a quick tune-up of the radio receiver and see what we can hear [Music] to get the capacitors out of circuit here it doesn't look like it's going to be too big of a deal a lot of these older circuits they wrap the wires this looks like this just might be laid down it is that's very nice and this one here too and as for the upper one that off the end there looks like it might be coming out again what they do with ice a lot of the time is they put the wires through and bend them around so luckily these ones weren't these traces they're not the strongest so they like to like to come off the board so there's those two capacitors there now if i heat this there's a good chance that i can probably just pull this out so i'm just i got my fingers on here and i'm going to pull on this so grab the iron so i'm putting some down force on this there it is there's one of them and the other one i'll do the same thing with so i'm just gonna put my fingers on here and push down like this in fact this one looks like it's kind of hooked upward so i might bend this one forward just to be a little easier on things like so and pull that down like so and there are those two crappy capacitors let's say here eberson ebar son interesting 10 volts 30 micro farad and this one here so you can definitely see the again the swelling of the seal on this one whereas this one isn't so bad see that right down there all right i'm going to get these capacitors replaced and while i'm at it i'll replace this one here and these two and we'll get into an alignment and this little radio should come back to life again i managed to find some capacitors that are very similar to the original ones and they're brand new i used the piping that was originally on them so the only difference is the body color and these capacitors here that i've also replaced look very similar to the original ones so that turned out very well so trying to keep it as close to factory as possible right so let's turn this thing on and see what happens what do you think let's witness this together so this looks like a speaker lead here i re-tinned that as well i stripped that back while i was doing this okay speaker attached here that's full volume kind of tune this it's kind of interesting picking up lots of noise from the desk yeah it's working well and it hasn't even had an alignment yet so not bad not bad at all not bad i have my signal generator attached to this loop of wire around the antenna the signal generator is set to 455 kilohertz and it's modulated by a 1000 cycle tone or one kilohertz tone and what i'm going to do now is i'm going to adjust these three transformers for a peak on the oscilloscope the oscilloscope probe is coupled directly to the speaker so i can adjust the amplitude with the volume control [Music] so i'll set it to a comfortable level just like that now what i'm going to do is turn each one of these and just look for a peak if i pass the peak i'll back up and adjust it until i get that maximum i passed it there right there's about the max now i'll move to the next one which is this one right here right about there's the max and i'll just go to this one right here now oh that one's way out so i'll turn the volume down [Music] and that's the max so i'll just quickly go over this one more time sometimes there is some interlock between the stages right there and one more time here and i think that about does it the only thing to adjust now is the oscillator and i'll adjust that when this is all back inside the case and i can see the dial so basically you know it's a crude dial tracking adjustment is really all that is so if alignment complete the radio went back together very easily everything fit just nice even that little piece of paper held up very very nicely in there so that's about as close to a factory or stock looking rebuild as i'm going to get so i have my signal generator set to 550 am and there's 550 on this little clip right now and it's modulated by a 1000 cycle tone i have the radio set to 550 there is a lot of switch mode power supply noise in here so i'm hoping that we can do this alignment relatively easy so what i'm going to do is place this close to the antenna and align this until the radio here is 5 50 am so i'll put this in here it's very close hear the tone there [Music] so i'll shut the tone off on the signal generator and there it is again and shut it off so this is extremely close so this whole area they've kind of locked things in place so i imagine this is going to be very close as well so what i'm going to do is go to the top of the band and i'm going to adjust this at 1600 am that's switch mode noise these antennas are extremely directional so you can use these things to find noise in your house as well so at least i'll turn this down i'll move this up to 1600 am so as long as it's within the window so if it tunes to 1600 here or here as long as it's within this window that's close enough we're not dealing with any type of uh crazy type of accuracy here so i'll just put this in the middle and we'll see if we can hear 1600 am so 1.6 megahertz and i'll make sure that mod is on i'll turn this up put this here and there it is so now what i want to do is just make sure that this is to its maximum sensitivity so i will adjust this one right here and it's extremely close so all this did was peek up the top end of the band if i move this one here around what it's going to do is it's going to completely shift the whole dial so i want to leave this one right here alone so it is very very close at least close enough for this small little radio so what i'm going to do now is put the back on the radio here and we'll take a listen around the band let's take a listen to the radio so it went back together nicely now this is very directional because it has a rod antenna inside so i'm gonna probably have to move this around for the best reception this area right here is really an rf dead zone so i'll turn this on i'll move the radio around a bit again [Laughter] [Laughter] the fact that people wake up and go [Laughter] so you can hear it's very directional and of course you know there are sweet spots where here's better just off to my side here is where it seems to be the best lots of switch mode noise that's switch mode noise so you have to find the null so the radio works very very well for what it is and especially for being in here where all of this incredible amounts of switch mode noise and everything is so as you can hear moving it to a sweet spot is you know the thing to do again this has a rod antenna inside and they are very directional in fact you can use these things to find noise in your house so you can use these things just to track down noise and it's you know they're as you know vertically horizontally polarized you can see i'll move this on an angle here so you can see i have to hold this in the perfect spot here with all this noise to try and keep the antenna out of phase with that the radio has lots of volume and if this was to be used outdoors this thing would receive like you wouldn't believe this is fantastic for receiving inside here pretty much any radio that's on the bench just hears noise and very little radio station so the fact that this thing is even receiving anything off that little teeny rod antenna inside that's all it has is really quite fantastic so for six transistors this is doing very very well oh yeah i was going to show all of you that schematic which is in the back here so what i'll do is i'll pop the back open i'll grab a different lens and we'll take a quick look at the schematic for this little six transistor radial here's a closer look at that really small schematic so this here is the oscillator transistor this is the first if transistor this is the second if transistor so these are if amplifiers this is the detector diode right here this is the volume control this is an audio driver transistor so this is the interstage transformer right here and we have a cute little push-pull pair of transistors here driving the speaker through this transformer right here you have the option of a earphone over here battery is down here now i do notice some discrepancies between the schematic and what was on the actual circuit board and this really is quite common usually as these things are going down the line sometimes they'll amend values but usually it's such a minor thing that they don't bother changing the schematic because it really doesn't affect the functionality so again you know the capacitor values and some of the areas here are a little different from what's on that board now i know that board is completely original because we together pretty much peeled up that piece of paper it was glued to the circuit board itself right so we are the first that have been into there you know into that little radio to actually service it so there you have it there is the little schematic don't forget to check out shango 066's channel if you're interested in these types of radios and watching them get restored as well again i'll put his link just below the show more tab under the video's description if you're enjoying my videos you can let me know by giving me a big thumbs up and hang around there'll be 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 being notified as soon as i post a new video don't forget to tap that bell symbol 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 comments section so if you click on the link it'll take you right there alright until next time take care bye for now you

Channel: Mr Carlson's Lab

Views: 88,387

Rating: 4.9728403 out of 5

Keywords: Transistor radio repair, tube radio repair, transistor circuit troubleshooting, electronic troubleshooting, electronic engineering, electronic repair, circuit repair, test equipment, electronic diagnosis, electronic fault finding, fix electronics, fix circuits, repair electronic circuits

Id: vzfliznVRkY

Length: 46min 7sec (2767 seconds)

Published: Fri Aug 13 2021