Hi,
I bought a super cheap vintage transistor radio Telefunken Partner from circa '57-58. Managed to clean it up visually, repaired cracks and replaced all electrolytic capacitors. However, looks like the previous owner tried to service it and failed miserably, breaking the output transistor to smithereens. The transistor in question is "OC604 spez". It should look like shown below, but all I've got is the "guts" of the transistor without the glass body or legs. It appears to have a large metal base with a radiator at the top to help dissipate the heat better and a bead on each side where the emitter and collector used to go.
One option would be to just use some other transistor. I think I have few AC122 that *should* be close enough.
But I'm thinking of another option - is it possible to fix it? Looks like all it's missing are the two leads, one from each "bead". Do you think it's worth the effort to try to fix it? All I have is a 40W soldering iron which would probably kill it, but I could take it to a computer service shop where they have more precise equipment to do it, provided there's a chance it could work as in the old days. Is transistor damaged by not being in a glass body?
Thanks all!
I bought a super cheap vintage transistor radio Telefunken Partner from circa '57-58. Managed to clean it up visually, repaired cracks and replaced all electrolytic capacitors. However, looks like the previous owner tried to service it and failed miserably, breaking the output transistor to smithereens. The transistor in question is "OC604 spez". It should look like shown below, but all I've got is the "guts" of the transistor without the glass body or legs. It appears to have a large metal base with a radiator at the top to help dissipate the heat better and a bead on each side where the emitter and collector used to go.
One option would be to just use some other transistor. I think I have few AC122 that *should* be close enough.
But I'm thinking of another option - is it possible to fix it? Looks like all it's missing are the two leads, one from each "bead". Do you think it's worth the effort to try to fix it? All I have is a 40W soldering iron which would probably kill it, but I could take it to a computer service shop where they have more precise equipment to do it, provided there's a chance it could work as in the old days. Is transistor damaged by not being in a glass body?
Thanks all!
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AC122 is the same as the 604 and will directly replace it.
I used to scrape the paint off then and use them as variable gain amplifiers. Subject them to light and the parameters change quite dramatically.
I used to scrape the paint off then and use them as variable gain amplifiers. Subject them to light and the parameters change quite dramatically.
I think it would be difficult to solder to the germanium wafer, or rather the material that interfaces between the germanium wafer and the lead out wires without causing damage. Is it Indium that is used to interface the two ? That has a very low melting point and would likely 'disappear' if you used a conventional iron.
Not sure how atmospheric contamination would affect an uncased and unprotected junction either.
Just substitute it would be my advice.
Not sure how atmospheric contamination would affect an uncased and unprotected junction either.
Just substitute it would be my advice.
Like a photo transistor. The only difference between the old OC71 germanium and the OCP71 (photo transistor) was the use of a clear 'jelly' in the package and no paint on the outside.
Old germanium devices can 'cause' issues if the paint is chipped/damaged and the device is run under bright light or fluorescent lighting because the junction is light sensitive. Any semiconductor junction (P-N junction) can become a photo diode/transistor if light is allowed to fall on it.
Old germanium devices can 'cause' issues if the paint is chipped/damaged and the device is run under bright light or fluorescent lighting because the junction is light sensitive. Any semiconductor junction (P-N junction) can become a photo diode/transistor if light is allowed to fall on it.
I got caught out once with fluorescent light falling on a 1N4148 diode causing hum in an amplifier.
I've heard of that happening... its a neat fault for sure and something you might only twig once you realise the hum level varies as you shade the part.
thanks everyone for replies. I took your advice and replaced the transistor with AC122 and got it to play (at least the AF amplifier stage). I wanted to try to keep the original parts because this is a rare first edition of the radio (the first ever production model from Telefunknen), but a broken OC604 won't keep a better value than a good AC122.
It's a cool looking thing, looks much better after I cleaned it
Cheers
It's a cool looking thing, looks much better after I cleaned it
Cheers
An externally hosted image should be here but it was not working when we last tested it.
Agree, it used to be pretty rough, but now it's much cleaner now
An externally hosted image should be here but it was not working when we last tested it.
Wow, what a transformation! Sure looks nice now. Glad the transistor swap worked for you. I'm of an age where these early transistor circuits are fascinating, remembering back to the transition between tube and solid state and the design choices made.
I was born way into the IC era, but I still find these early devices fascinating. I like comparing different circuits made in different parts of the world and in different decades. It tells an interesting story.
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