Yamaha EMX88S Channel Problems

[Notsosparky]

Hello,
I'm a newb so please don't shoot me. Just picked up a EMX88S and having problems with channels 1,2 & 3. I have the schematics but wanted to ask where to look from some more experienced folks. Disassembled and checked low z and high z connections and they all look and check solid. If you crank the amp you can get minimal signal thru the speakers thru both the high z and low z inputs. Can anyone steer me to what section of those channels I should start checking components values?

Thanks

[Jazz P Bass]

It's probably not a 'component value' find that is going to get this running.

My bet would be the first opamp that the signal sees.
U101 on channel 1.
U201 on channel 2.
U301 on channel 3.

Be aware that the opamps are of the surface mount type & that it takes special skills & equipment to change them out.

[Notsosparky]

Thank You for the info, I'm not a schooled tech but been able to do my own repairs for 30 years. This is a great forum

[Jazz P Bass]

If you have access to a signal generator that would help immensely.

With that & a DVMeter you can trace out the failure.

[Enzo]

Are those channels also gone from the monitor mix, or do those work? The monitor send comes off before the channel fader, and so helps isolate the problem.

[Notsosparky]

Yes the monitor is also inop on those first three channels, still sound like the first op amp's are the problem?
Thanks

[Enzo]

Probably, just like to make sure first.