jetgraphics wrote:
Scott Dorsey wrote:

Well, have you gone through with a scope and a signal generator and
followed the signal. Is it on the buss? Is it going into the makeup gain
amp? Is it coming out of the makeup gain amp?

Are all four channels handled by one quad op-amp by any chance?

Got scope (old 40 MHz), got no signal generator.

Get a signal generator, or a CD player with a tone CD on it. Or ground one
input pin to produce a hum (always a handy tone source in a pinch).

Got visual impairment, no can see good, anyway.

Then get a signal tracer instead of the scope, so you can tap a probe on
traces and listen for signal there. Not a very fashionable thing to use
any more, but very underrated if you ask me.

If you have trouble seeing the tiny pins, a headworn magnifier and _very_
bright desk lamp can help.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."