Hello friends. I picked up a fixer Pinbot with a laundry list of issues. The sound worked when I got it, but now it's silent except for a mild hum.

- Turned the volume all the way up: crackle and hum. No startup bong, no sound at all. No sound when pressing the sound test button.
- Applied Deoxit, now just hum. Progress.
- Applied a powered soldering iron to center lug of volume pot: a little more hum. This means the amplifier is good I think
- Put the sound board in my other pinbot. It works.
- Pin 4 on J3 on the sound board should be -14VDC. Verified on good pinbot. 0V on bad pinbot!
- Power board TP4 should be -14vdc. It's +0.7vdc!
- Power board TP3: +11.7VDC. This means BR1 is good, right? I mean bridge rectifiers don't half-fail, do they?
- Pulled C9. My cheap multi-tester gizmo seems to think it's ok. Does the ESR seem right? I don't have any new 1000uf caps to compare with.

What would you suggest next? Thank you!

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Thanks all. Seems to me that BR1 went half-bad! I'll circle back once it's replaced.

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Thanks for the heads up. Who makes capacitors we like nowadays?

Thanks for the help everybody. The half-bad BR and the original good cap have been replaced with an NTE BR and a Nichicon cap and I am victorious!

https://www.instagram.com/p/CEFO2TQBIZg/