1947 Electronics - Will It Still Work Today? Find Out!

hi everyone and welcome to another episode of mr carlson's lab let's get started the story on this thing goes this thing was in use just up to recently and supposedly it's all original inside so supposedly i haven't seen inside and really nothing's been done to this thing since well 1947 supposedly and it still works with all the original components so i figured you know what let's check this thing out together and see if this is actually true or not now one of the things that i noticed on the back which was uh just a wonderful piece of engineering here i have to show you this so move this out of the way look at this thing just get the light on this pardon the camera shake here for a minute look at this chunk of engineering look at this yeah what is going on that's pretty looking pretty green in there along with this huh so these are obviously the pins and somebody's taped up the pins and they've carved this down pretty good in order to make this plug into what's in that little hole there yikes that is one scary piece of engineering ah anyways so we won't be using that okay give me just a few moments here i'll get some screwdrivers and let's open this thing up and see if it is all original and then let's put some power to it and see if it actually does work like it's said to all right i've got i think all it takes to get this thing apart so let's take the uh knobs off here first it came off relatively easy same with that one and let's take this one off okay so that's looking pretty good so far that's uh it's nice soft mat here so i can just lay this forward all right let's take these screws out and see what's in the back here i'll just take them right off oops there's another screwdriver there knocked it over i always enjoy things like this you know they say that oh you know it's nothing's ever been done to it and it's been working since the beginning and blah blah blah it's been in my family for so long and this that in the other and you know it's always interesting to see you know maybe this is true you know you never know sometimes the uh stranger things have happened so i'll just take this out wow looks like some brief touch there or something like that doesn't it maybe something poked through the back over time a big old light bulb in the middle there to light up the dial big bright light that just shines over everything you gotta like that there's that interesting outlet so it's actually something fit inside here from the back so when you took the back off it was like a safety interlock kind of thing that's kind of neat for a way back when so interesting so on the bottom oh we only have one screw and it looks like there could be two missing so i don't know let's see i'll attach this here okay here we go looks like uh oh the speaker is part of the the front here so it's gonna have to slide out and i think it's gonna hit this top block here so i'll have to tip this forward somewhat like a stromberg carlson and let's see if i can turn this upside down so we can see what's on the underside that's looking almost completely factory maybe aside from the uh the filco capacitor so somewhere down the line this got put in but this wouldn't have been no too far from its manufacturer all right so what i'm going to do is i'm going to steady this thing and let's take a closer look on the underside well it's honestly looking like it is very original if there was any work done to this it would have been done you know very close to the point of this thing being released like this capacitor here looks like it might be the most modern piece in here and it's probably not that far off six of 1950 so yeah just a few years up really so 47 you know to 50 really so it's all looking like it is very original so not bad that i guess the original filter can went bad pretty early which isn't uncommon for older radios like this all the waxes are in here yeah it's it really is so the owner of this really isn't far off so maybe they just missed this one little date that it went in for a quick service or whatever right so i guess the next thing to do is to see if the second part is true what i'm going to do is hook this to a current limited isolation transformer and variax apply i'm going to bring this up slowly and let's see if it receives anything and see if it actually does come to life okay i'll bring this radio up really slow on the dim bulb tester here so i'll turn this on if anything goes wrong these lamps will get very very bright so they should glow dimly i.e dim bulb tester so i'll just turn this right up and i should get a bit of a glow and that would indicate that the radio is drawing current because that's a little bit brighter than normal and i can see a filament coming on right here oh and here too dial light doesn't seem to be working though does it that's loose ah there we go i'll just leave that off oh i hear static oh it's coming to life at reduced you know voltage as well right it's nowhere near the line voltage right now wow let's move this out of the way it's nice and quiet when i touch this so obviously i'm introducing some noise into this and that introduces hum this is isolated from the chassis that's interesting the volume control itself is isolated from the chassis interesting turn that down there's almost no hum in this radio that means that that filter capacitor from 1950 is still working well well i guess the owner was uh was telling the truth in this case it's trying to receive at reduced voltage right now if i flip this up it'll bypass the bulbs and give this full line voltage so what i'm going to do is i'm just going to let this run like this for a while to basically i guess you could say try to condition the capacitor people would like to say reform it but i'd like to just let things stabilize for a little while here before i actually give it full line voltage because i don't trust that original filco capacitor and well really all the rest of it at all either so i'll let this run like this for just a little while while monitoring it to make sure nothing goes wrong and then what i'll do is i'll flip the switch and uh we'll see how well it actually does receive it requires an external antenna that's what this wire is for so we'll give it an external antenna and see how well it receives all right it's been basting on that isolation transformer and current limited variac supply for a long time so hopefully this capacitor will hold up at direct line voltage let's find out here we go and it's now on as you can see i tightened the light bulb up as well so you can see the dial i don't know if that's too bright maybe i should cover the cover the bulb maybe it looks better without it and probably needs the bulb in there wow okay so what i'm gonna do here is this is probably just picking up noise the way this is here because there's some noise in here so i'll just cut that off wow listen to that it went silent okay so now i'm gonna hook this up to the 369 antenna i have lots of videos on that so i'll attach this to here and this to here and i'll just tune around the dial there's a station [Music] wow so just be prepared i'm john furrier [Music] wow with all those original parts this thing is actually working [Music] it's relief [Applause] [Music] wow so it actually is working quite well boy is that ever bright the thing is really working well for you know all the original components now i can obviously tell that the sensitivity is down but it's uh very very surprising that this thing is working and it's with the original filter cap there is just a touch of hum in there just a just a touch of hum so it's it's working very well yeah i'm very interested to actually see how leaky some of those capacitors are so what i'm going to do is i'm going to flip this upside down and we'll take a look at some voltage measurements on on different portions of this radio i'll be right back the radio has been on for a short period of time let's see how much dc is leaking across this wax capacitor to the output tube so what happens here is there has to be plate voltage dc voltage on the plate of the amplifier tube in order for this tube to work now what happens is is there's also audio at that point as well so the capacitor's job is to block the dc that makes the tube work and only let the audio signal through so there should be virtually no dc at the grid of this output tube right here if there is any dc on there what it does is it change the bias point of the tube and drives the output tube into heavy class a if the output tube is driven into heavy class a it draws heavy current through the audio output transformer as it's drawing heavy current through the audio output transformer it drives the transformer more into saturation because there's more dc on there but what it also does is it heats the windings and that destroys these audio output transformers and as i can see already the windings in here are kind of dark so the actual paper is darkened in this transformer so over time as the radio sits on these capacitors as they heat up they get leakier and leakier until you get a really bad problem so what i'm going to do is i'm going to measure the dc at the grid of this tube let's take a look at the dc here and see what's there it should be basically zero so there should be no dc there whatsoever and as you can see we have 0.8 of a volt so we're approaching one volt of dc at the grid of that tube right there and that is a really bad thing so as this radio heats up more and more that will pass more dc it's just it's a common trade of these old wax capacitors and then what ends up happening is it ends up taking the tube out and a lot of the times it'll burn out the audio output transformer now what i'll do is i'll i'll turn this off here and i'll move this out of the way let's get this out of here this stuff that's holding my meter so you can see it properly now if we look at this let's zoom on into that transformer you see how dark that is you can see how dark colored that is so chances are you can even see on the other side it looks really dark over there too so what's happening here is chances are this is it is even getting hot right now that's nice and warm so what's happening is just that little bit of a bias change from this being on for a short period of time is heating that transformer already and this is why if you ever purchase one of these older radios say from an auction or whatever and somebody offers to demonstrate it to you but it hasn't been rebuilt i always say no don't plug it in don't turn it on because that might be the last time that it actually works a really common failure point is these filter capacitors what they end up doing is they short and then they blow the cathode bonding wire off of the rectifier tube so then you have a bad filter you have a bad rectifier tube and then you have to go through and rebuild all of this now mind you these tubes are still available you can find these all over the place let's see if i can get this rectifier tube out to show you there it is so i don't know if i can zoom into that cathode bonding wire for you it's a connection wire that they've uh see that little connection wire right there that acts as a fusible link inside the tube that little wire right there that connects to this little pipe that's in the center here you can see a little bit of that pipe there that's in the center of this here that's the cathode and then what happens is the dc is present on that point it comes out here and then runs out to one of the pins on the bottom of the tube well that's the part that goes away if the capacitor shorts it just destroys this little strip that connects from the cathode to that lead out now again these tubes here are still relatively available 35z5 is a pretty common rectifier tube all this is a diode all right that's all that this is so they're still relatively available but you know what it'll cost you some money if you know something goes away now there's a lot of other things that can happen with a radio that's all original like this there's a lot of capacitors that can fail it can cause failure of the if transformers it can cause more tubes to fail it can burn all sorts of things out so always keep that in mind if somebody offers to demonstrate a radio to you they say it works all right but you know they're saying i'll plug it in and show it on if they say it works it's almost worth in my own opinion of course this is up to you it's almost worth just saying okay if you say it works you know what i really want the radio or whatever i'm willing to take the chance i'll you know and then take the thing and then of course you rebuild it before you power it up or of course like i did you know have a current limited isolation transformer and a variax supply where you can bring the thing up safely plugging this directly into a wall is not a safe thing at this age for multiple reasons which i've talked about in many of my other videos so something to keep in mind so this will make a really nice restoration it's working well already with what's in here you know and who knows how long it would keep running as you can see this is you know going bad very fast so this radio should come back to life and be a very nice restoration if you'd like to see this radio restored in the near future you can leave that in the comments below we'll go through the entire procedure together hope you enjoyed see you all very soon 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'd like to be 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

Channel: Mr Carlson's Lab

Views: 90,259

Keywords: Restoration video's, repair video's, restore electronics, test electronics, fix electronics, electronic engineering, circuit design, capacitor testing, capacitor tester, test equipment, electronic labs, Mr Carlson's Lab Videos, learn electronics, tube amplifier repair, tube amplifier design, repair electronics, Tech Talk with Mr Carlson

Id: 8hWL4dTAtlY

Length: 17min 58sec (1078 seconds)

Published: Sat Nov 06 2021