Thank you very much for taking the time to look at the schematic! I'm afraid signal tracing is beyond my abilities so, yeah, I'll have to hunt down a tech. Thanks again.
Dan
Dan
Quote from: J M Fahey on February 06, 2010, 06:06:07 PM
This won't be easy, may end up being real frustrating, because the amplifier is (unnecessarily) complex, the signal zigzags from board to board, there are some "mutes" including an "effect kill", the classic tests involving effects send and return don't apply, because in this case they are *not* pre-out and amp-in, there are *lots* of connectors, and ribbon cables, etc.
Anyway hook some music in the input, send effects out to another known good amplifier, to check the preamp, and send some music to the effects return to check the power amp, although as I told you before, things are not that straight here.
I think this is one of those cases where the oficial service is recommended.
Truth is, here you need a signal generator and a scope to trace signal stage by stage.
Just for starters, you have a mute across Gain (Q1), an effects bypass across U9a (Q5), an FX kill and an FX Rtn kill (Q9 and Q11), a mute across Master volume (Q2), a switchable limiter across U10b, plus all those ribbons and connectors where signal goes through.
It's not a job that can be "remote control run " as others.
Sorry.