Solid State Guitar Amp Forum | DIY Guitar Amplifiers
Solid State Amplifiers => Amplifier Discussion => Topic started by: bry melvin on July 03, 2010, 02:16:47 PM
I would appreciate a little help as I'm stumped
One channel output power amp was burnt/toasted. Don't know why. I picked this up for my son on ebay. Basket case
Cheap
Q11, Q10, Q5, Q9 were toasted as were r17 r25 r21
R26 was open cracked
Q6 was missing !?
D4 was shorted
R26 was open
I also changed Q8 although it tested good.
Fixed two traces where the cooked parts damaged the board.
I replaced r26 and 27
Now that channel works!
All I get on the right channel is noise and loud buzz.
I had bought extra output parts so q101 thru q111 were changed...still bad.
R 126 127 were changed too
Voltages are ok at TP4 not at tp5 didn't write it down but was really low.
Have multimeters but no scope signal generator etc.
All the jacks seem to be working properly
schematics are here:
https://docs.google.com/fileview?id=0B_cPagiySScIMTc0YzQ2ZDktZjNlZS00ZmIyLTkwZDEtNDM1ZmNhZGU4MDIy&hl=en
Preamp works going into another amp through the mixed jack.
Solved: Careful of this schematic....parts< than 100 are LEFT channel >100 right
...schematic says..."left channel same as right add 100 to parts....