Here is a typical list of damaged components when and output transistor shorts C-E.
Some may diode check OK but.. They are all within the debris field and have been exposed to excessive current.
TR104,106,108,110,112,114,118,120,124,126
R136,138,152,154,158,160
D112,114,116,118---114 & 118 are zener diodes
I've seen TR102 ( 2SK389BL) take a fatal hit on several occasions.
Each case is a little different .Maybe more parts,maybe less.
Thats why I stated earlier to check all the transistors and diodes in the bad channel.
I print out this shematic on legal pad sized paper and highlight those parts that check bad as well as those that check good. Helps me plot the path(s) of destruction.
http://akdatabase.com/AKview/albums/userpics/10004/Yamaha M80 Schematic with TSB66.pdf
I won't hijack the thread, but we need to work on a plot for my dead MX-2000 some day.
I think I have the input board sorted out, but one channel board has .5VDC on the idle current and it's still coming up in protect. I'm baffled. :scratch2: