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Found an old speaker amp, doesn't work, is it worth repairing?

post #1 of 9
12/13/12 at 6:57pm
Thread Starter 

So this really old speaker amp happens to have come into my posession. It's unbranded and appears to be homemade. I plugged it in and turned it on and the light at the front illuminated but one of the components on the board (one of the green capacitors I think) started smoking.

 

 

 

Would this be fairly simple to repair? Is it even worth trying to repair it?

 

Picture of internals:

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post #2 of 9
12/13/12 at 7:29pm
Quote:
Originally Posted by fraseyboy View Post

So this really old speaker amp happens to have come into my possession. It's unbranded and appears to be homemade. I plugged it in and turned it on and the light at the front illuminated but one of the components on the board (one of the green capacitors I think) started smoking.

Would this be fairly simple to repair? Is it even worth trying to repair it?

You might want to ask this about this on the AVSforum and AVforum.

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post #3 of 9
12/14/12 at 5:47am

A repair might be possible if you get good advice, particularly if you can find somebody who recognizes this particular bit of kit.

 

Very often the best thing to do is a salvage operation, where chunks of the original are kept, such as the power supply.

 

Do you have a multimeter and know how to use it?

 

If not, the learning curve will be very steep for you, it might be better to give the whole thing to somebody else, either to fix, or as a gift.

 

w

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post #4 of 9
12/14/12 at 3:33pm
Thread Starter 
Quote:
Originally Posted by wakibaki View Post

A repair might be possible if you get good advice, particularly if you can find somebody who recognizes this particular bit of kit.

 

Very often the best thing to do is a salvage operation, where chunks of the original are kept, such as the power supply.

 

Do you have a multimeter and know how to use it?

 

If not, the learning curve will be very steep for you, it might be better to give the whole thing to somebody else, either to fix, or as a gift.

 

w

I do indeed have a multimeter and I sort of know how to use it. It'd be useful to know whether the components are good quality at all. I could probably get a second hand vintage amp for like $20 so there's not much point putting too much time/money into restoring this one if it's not really any good anyway...

 

I'll post on AVSForum and see if anyone recognizes it.

 

Here's a photo of the front:


Edited by fraseyboy - 12/14/12 at 3:54pm
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post #5 of 9
12/14/12 at 4:23pm

sure looks to be mono. unless there is a second amp board.

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post #6 of 9
12/14/12 at 6:46pm
Thread Starter 

Well according to AVForums it's most likely a guitar amp from the late 70s. This explains the dual inputs on the front as opposed to the back.

 

Probably won't bother trying to repair it.

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post #7 of 9
12/15/12 at 9:29am

Nice big transformer there, don't bin that...

 

w

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post #8 of 9
12/15/12 at 8:20pm

Just by looking at the rectifying diodes, I can tell this thing is older than I am... 

 

A transformer this size is at least a hundred dollars new. I sure would not trash this one if it still works. The capacitors are probably all dried up, so it's safer to trash these.

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post #9 of 9
2/27/13 at 1:35pm

Its a stereo high-fi amp from the 70s The output device as are typical of that era as are the capacitors which were rubbish then.Looks 20-50 Watts.Especially with the large transformer. Every capacitor would need to be changed as they "dry-up" and S/C.Could be made working again with some work.The Pre-amp is hidden and capacitors in that would need replacement .Knowing 70s circuits -scrap the pre-amp and build/buy more modern one.to go with the amp. distortion is probably 0.05% upwards depending on the bias current.

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