If their's only crackling on one side and everything else sounds ok
through the output not out of the headphone jack it can be a noisy
transistor if you have a scope check the driver of that channel for noise. I
don't know the specific receiver but this is a general check for that type
of problem.


"jakdedert" wrote in message
news
Jerry G. wrote:
I cannot remember this set in detail, but I recall in many of these
sets changing the output devices, protection relay, and a fair amount
of caps. There were caps that were going high in ESR causing the set to
go in to protect, and also causing some device failures.
I was hoping it was a little less involved; but will go to a good deal of
trouble to get this one running. There are quite a few caps in there, and
I don't have an ESR meter. I believe the outputs are okay. The relay
could be an issue. Do you recall if it merely disco's the speaker outs,
or the B+/B- lines?

So far, in hopes of getting the schematic before doing detailed
t'shooting, I've only poked around, half at random. I did measure
voltages on the relay, and looked (in vain) for signal there. The only
significant voltage there was +/- 72v on two of the pins.

It does exhibit some symptoms of the protection circuit being the main
issue. As stated in the OP, there was no DC on the outputs when it was
working. AC voltage was even--channel to channel--and linear with
increasing input. I measured over 30v using only interstation FM noise
for a signal. I never got around to actually hooking up
speakers...instead used 100w dummy load, listened through the headphone
output. Both sides sounded clean except for the previously mentioned
intermittant crackling in the right channel.

Any other recollections of fixing this relic would be helpful...anyone?

jak
Jerry G.