Sansui A-80 bad connection

[joebarta]

Hey guys, I'm new to the forum and to vintage audio systems. I recently purchased a Sansui A-80 Amplifier, Sansui D-25 TT, Project One Cassette Deck, and Bose 4.1 speakers and have been having some issues with the Amplifier and Cassette Deck.

The main issue I've been having is with the Amplifier. Sound only goes to the one of the speaker sides when playing music (through the turntable or cassette deck and both A and B outputs). When I tap or move the Amplifier in any way, the sound changes (the right side can get some feed back, although never clear, the left side cuts out or gets crackly, or everything cuts out with some crackly feedback). I've done some research on this behavior and read that it could be bad relays but I'm not entirely sure how to test that or if that would be the case in this situation. I've opened up the lid and couldn't find any loose connections or cold solder joints but I could use a magnifying glass to get a better look. I am positive the issue is with the Amplifier and not the speakers. Also, the system was working fine when I first assembled everything. If you guys have any thoughts on what the issue could be, I'd be happy to hear them to start troubleshooting. If you need any extra information, pictures, or videos, I'd be happy to give those as well.

As for the Cassette deck, I think I'll wait on that until I figure this issue out as I don't listen to cassettes.

Thanks in advance!

[joebarta]

Any recommendations here?

[MacGeek]

If you are comfortable getting into the unit, I suggest starting with a good cleaning of all of the controls (knobs, switches and push buttons).  Dirty tape monitor switches are a common source of intermittent operation.  If you have a compressor, or a can of compressed air, blow out all the dust before cleaning.

Good luck.

[quaddriver]

suck the solder off the relay and yank it.  you can try to clean the contacts with 400-600 emory or even try to replace.

also not a bad idea to flip it over and do a touch and go on all the solder joints.  put on good glasses and look hard and closed to telltale signs of solder joint cracks.