[Jack[_11_]]

Mark Zacharias wrote:
"Jack" wrote in message ...
Jack wrote:
After a week of playing with no problems, the right channel went out. It
was the left channel previously. I was dismayed until I remembered that,
when I reseated the output trannies, I switch them, left for right. I
was further heartened when that same trick of switching off the speakers
and turning the volume up to max brought the sound back. Since there are
a pair of outputs in each channel, switching one of them again and
waiting to see which channel goes out next should tell me which tranny
is bad.
After switching back one pair of the output transistors, the PNP's, NEC
B539A's, the problem stayed in the right channel, so I replaced the
right channel NPN, an NEC D287A with an NTE284. It's playing fine at the
moment. I will button it up and consider it fixed until it tells me it
isn't.

Jack


If you have not cleaned the relay contacts yet - you are wasting your time.

Mark Z.

I cleaned the relays a couple of years ago when I tried to tackle this
the first time. Buffed the contacts with 1200 grit wet/dry sandpaper.
This time I tested the relays by bridging them when the bad channel was
out. didn't help. It wasn't the relay. The problem followed the NPN
output transistor when a swapped them left to right and right to left.