Guys:

This is not exactly that old ( by this sites standards ) but I thought anything with an 8-track player in it would be fair game.

I am fixing this combination unit for a friend. Looks like TWO out of the four diodes in the power supply bridge are burned up.What would cause only two to burn up? Perhaps an electrolytic short on the output would burn up a diode pair on one-half cycle? The other two in the bridge are pristine.

Thoughts?

Lou

Could have been a voltage surge or bad electrolytic cap. Why not replace them, and bring up slowly on a Variac...

I agree with Brian. Replace them...all four.

Clifton

:Could have been a voltage surge or bad electrolytic cap. Why not replace them, and bring up slowly on a Variac...
:

Yes - I agree

I have new electroytics to replace the ones in the power supply. I will replace all four diodes.

Just wanted to see if anyone else had an opinion.

lou

:I agree with Brian. Replace them...all four.
:
:Clifton
:
:
::Could have been a voltage surge or bad electrolytic cap. Why not replace them, and bring up slowly on a Variac...
::
:
:

If they are discrete diodes, an overload or sustained heavy load on the DC bus could have caused two to overheat and fail, sparing the other two simply because they were slightly more robust. Solid state electronics have come a long way in the past 40 years and variations between parts are much more tightly controlled now.

Whatever you do, replace ALL diodes in the bridge- either with four new discrete parts or a single integrated silicon bridge of an adequate current rating.