If you have signal on tape out + FX send but not on Master/Booth/Mono then i would first test if you have HeadPhone signal in CUE mode but not on the master signal (Just to verify that the HP/House ICs works.).
#1 Check if the EQ output caps looks ok: C32,C33 and C26.
#2 EQ ICs might be broken: IC31-A + IC3-A (TL072).
If all above is ok then i would check the FX return buffer: IC1-B and IC11-B (TL072), but these use the same ICs as the summing amp that works.
Last edited by Pern : 11-01-2011 at 01:55 AM.