I've been getting into vintage records ever since I found a beautiful Motorola Stereophonic at the local transfer station. Even though it was covered with snow, I brought it home, cleaned up, and it works beautifully. Sound like I wouldn't have believed.

So this week, I find this beautiful 1953 VM Tri-o-matic portable, brought it home, cleaned it up plugged it in and..... POOF!... flash, smoke, lights go out.... darn.

So, disassemble, survey the damage, and I see what looks like a little explosion of wax and whatnot from where the power cord enters the amp (by way of some waxey transformer-looking thing).

My 2 questions now are, What happened? and What can I do to get this thing running again?

How easily can i replace the amp and/or power source? I feel moderately comfortable (though not particularly knowledgeable) tinkering with electronics, and this seems straight-forward enough, but not sure where to begin (and I'm not the kind of guy to scrap something with this much character

Thanks!

You'll learn.

.... to not plug in things I find at the dump?

From what you say, I suspect this record player uses a power transformer. That can be identified as a big iron thing on top of the chassis. It's used to convert the 120 VAC from the powerline into the necessary voltages to operate the set. The better models used a power transformer. The cheaper models ran directly off the AC line and the tube filaments are wired in series.

Anyway, getting back to your problem. The first thing I'd do is obtain a Sams Photofact service manual for your unit. It will contain the schematic and parts list for your record player. It sounds like either a capacitor blew up; or, the power transformer shorted and went up in smoke. Usually, something like a shorted capacitor causes the power transformer to burn up.

Often, no matter rather your set uses a power transformer or not, there is a capacitor that is connected directly across the AC line. These capacitors are known to short and they can cause the results you describe.

In fact, it's events like what you describe is the reason why we advise to never plug in a vintage piece until the capacitors have been replaced and any other obvious problems have been fixed. Those old caps can short without warning and they can cause expensive damage.

As far as the power transformer, here's how I'd check it. First, remove the rectifier tube (5Y3, 6X5, etc). Now, connect a 100W standard lightbulb in series with the AC input. If there is a short, the lightbulb will provide a load and prevent other damage. Once you have the lightbulb wired into the line, apply AC power and turn on the record player. If the bulb glows brightly, you have a shorted power transformer or something shorted in the primary side of the transformer.

If the bulb glows dim, check the AC voltages at the secondaries of the power transformer. The HV winding will probably be around 700 volts with a center tap (350-0-350 volts). Then, there will be a 6.3 volt filament winding. If the set uses a 5Y3 (or similar) rectifier tube, there will be a 5 volt winding. With the bulb in place, the voltages will probably be lower than normal; but, it will give you some idea as to the condition of the transformer. As a further test, leave the transformer powered up for 30 minutes or so and keep an eye out for overheating, dripping wax, or extreme odors. If the bulb remains dim and nothing unusual happens, you can likely safely apply full power, without the bulb in series, and re-check the transformer and it's voltage output.

If the transformer is bad, replace the rectifier tube and replace both the electrolytic capacitors and the paper capacitors. In fact, the caps should be replaced no matter what.

If the power transformer is bad, a new one will cost you between $50-$100. Or, you can probably track down a used one for under $25. If you have to replace the transformer, use your ohmmeter to test for shorts on any of the supply lines that get voltage from the transformer. This is especially true of the high voltage B+ line. I remember an ancient guitar amp that was brought to me by another technician because it kept blowing rectifier tubes (it was well on it's way to frying the power transfomer) and he couldn't figure out what was wrong. It turned out that the primary winding of the audio output transformer was shorted to the core; thus, shorting B+ voltage to chassis ground. So, don't overlook anything. I recently fixed a Magnavox record player where the transformer caught fire and the primary winding eventually burnt open. I fixed it; but, I had a mess to clean up.

Since yours is a VM unit, you can probably get parts from Gary at http://www.thevoiceofmusic.com. Without looking at your amp, I can tell you that it's repairable. It will be up to you as to how much money or time you'll want to invest to get it going; but, it can be done.

If you have a variac, you can plug the record player directly into that (without the bulb). Start the voltage out at zero and gradually increase the voltage while watching the current draw on the meter. If the transformer is shorted, you will see the current draw sharply rise without a whole lot of voltage input to the transformer.

I suspect that the "dim bulb" here is the guy who hauls home a 1953 VM tri-o-matic (or a 1953 ANYTHING) and plugs it in before he is sure it is safe. There must be THOUSANDS of posts on this site dealing with this same subject. It seems some guys never learn.............GREG

Waxy and transformer are not a typical combination. Considering how inexpensive these players were, I've got a hunch (could be wrong) that there is no transformer at all (well. maybe for audio output).

Could you post a picture of the damage? I'm kind of expecting to see a blown up electrolytic capacitor in a transformerless AC/DC amplifier. I could be completely wrong, but if so the damage would not be too serious. If it really is a blown up transformer it may not be worth repairing.

Curtis Eickerman

Thanks Eickerman and RadioTVNut... that gives me enough to get started on. I knew it was a good idea to recap a new player, but didn't know the exact reason why. My dim-bulb just got a little brighter... I'll get started with your suggestions and try to post those photos, I'm curious myself....

Up until the mid 1960's, most capacitors were not that great and many absorbed moisture easily. A capacitor is supposed to block DC; but, pass AC. As these capacitors age, they become electrically "leaky" and start acting more like a resistor than a capacitor. At this point, they will pass DC; which, they are not supposed to do. Over time, this leakage becomes worse until a dead short takes place. Depending on the circuit and the degree of leakage of the capacitor, serious damage can result to expensive parts as a result of excessive current draw due to the bad capacitors. These capacitors will go bad from sitting unused for decades and they can just as easily go bad from use.

Fortunately, modern capacitors are, for the most part, far superior to anything that was in use back then. Most of the newer caps that we used to replace the older caps will still be just fine decades from now.

You find something thats 50+ years old at the side of the road, take it home and without even looking at it you turn it on (it goes bang)
It still blows me away that people come here shocked and suprised and asking why?, The solid state stuff i haul home i wouldnt do that with and to be honest in most cases id have more chance of getting away with it.
I always take the back off and give a visual inspection, that tells me a lot on solid state stuff , even then i use a limiter for first power on.
Im just not the type to haul something home and waste gas and time by making it go bang because i was thoughtless, its old equipment, valve or solid state it needs TLC before you apply power.
Ive seen it so many times here, you could make a book out of the stories people tell, yet we still get more.
Im sorry if the OP feels im having a go at him, im not its just if care had been taken he wouldnt be asking about the damage hed be asking how to restore it

I never plug in a 50 year old radio, amplifier or record player until I replace all the old wax capacitors and, the old electrolytics. Do this first every time and you'll eliminate these types of problems.

OldMusicMan, I don't feel that you're having a go at me... but I am hoping that the point of your message (and everyone who posts here) is to educate and encourage interest in what is obviously an important issue for you. If I didn't want to learn to restore, I wouldn't have bothered coming to this site.

Look, every forum for every hobby under the sun has members whose goal is just that, and others who just shake their heads "tsk, tsk, how dumb are you, why can't everyone know what I know". I expected a certain amount of hazing about this, and got it, but I also got some good advice and encouragement, which makes me want to fix said record player, rather than chuck it in the bin like the last guy did....

Thanks for taking the time to read my post, now go out there and look for someone else new to this hobby you can encourage...

oldmusicman, we are on the same page. You said it nicer than me. I have absolutely zero sympathy for anyone who hauls something out of the dump, regardless of its age or what it is, and then expects it to operate like new. Would the OP have taken a 1953 car he hauled out of a junkyard and then try to drive it coast to coast? Probably on four flat tires and with a bad transmission? If he did, and broke down, would you shed any tears? Learning is one thing to encourage. Not using common sense is a different kettle of fish. This has nothing to do with "not knowing all they know". He made a decision that was not in his best interest, and now he wants our sympathy and for us to bail him out. If he can ask questions after the damage is done, why could he not have asked before he plugged it in, if he is so interested in learning?...........GREG

Give the guy a break, gentlemen. He was green, made a mistake and learned the hard way. Get over it. He obviously wants to right himself, and won't be making that mistake again.

I agree. Yes, there are millions of postings on the internet and in various publications regarding not plugging such items in until they are gone over. However, when most people find something, they don't take the time to search the internet before plugging it in. What happened was in the past and the OP can't go back and change anything. All that can be done is to go forward, try to help the OP correct the problem, and hope the OP learns a lesson from this experience.

Chances are good that no harm was done anyway. By your description is sounds like a line bypass capacitor blew its innards. It’s not pretty but it's not the end of the world either.

After your experience with the Motorola, you were probably feeling pretty lucky.

Please post a clear photo, so we can help you sort out what went wrong.

-David

Is THIS a clear enough picture, David?

NEVER REPLACE ALL THE CAPS BEFORE YOU PLUG STUFF IN . DONT !

It may turn into junk .

The power cord probably shorted together where it goes into the amp . Fix the cord and plug it back in . Variacs are of no use .

"fix the cord and plug it back in" variacs are of no use"

great then watch it burst into flames and take his house with it.


Do you realise you could kill him with your advise?, if there is further damage done and the OP manages to rewire the cable whats to say the whole chassis and turntable isnt now live? you think a death is a small matter?
Ive read other posts where you say dont replace caps just plug it in, you seem to have a thing for dangerous practice,
The phongram is obviously dangerous and needs to be looked at by someone who understands the OP and u clearly dont.