Radio Shack Amplifier Schematic Needed

[caverat]

Need a schematic for an Optimus MPA 125 PA Amplifier. Hard to find!

[Jazz P Bass]

It doesn't look like that exotic of an amplifier.
Other than the 70 V line transformer.
User Manual here:https://manualsbrain.com/en/manuals/1109625/

[caverat]

Unfortunately that is just the user manual, no schematic. I have that. This one has problems back in the preamp section. Has several standard ICs, dual OP Amps, but without schematic hard to follow which is which to do a signal trace

[glebert]

You have four input channels with 1/4" or XLR. The XLR come in on the lower daughter card and look like they head to IC1 and IC2. The 1/4" inputs look like they come in "later" in the circuit and go to IC3 and IC4. I'm guessing things head over to the front panel pots on that big wire bundle next. There is maybe a buffer stage and then it maybe heads to the back panel switch for bypass/eq, etc. Seems like you should be able to break it down that way, but I am armchair quarterbacking.

[vintagekiki]

at least something

http://web.archive.org/web/20120228195017/http://support.radioshack.com/support_audio/2842.htm

http://web.archive.org/web/20120115160410/http://support.radioshack.com/support_audio/49019.htm

1)
https://www.vintageshifi.com/repertoire-pdf/pdf/telecharge.php?pdf=Realistic-MPA-40-Schematic.pdf

https://www.electronica-pt.com/esquema/old-tv/realistic-mpa-40-50339/