Trace Elliot GP12X, 350W with severe buzzing

[dpm309]

Looks like I am becoming the Trace Elliot go to person in Arizona. Have another TE GP12x, 350 Watt bass amp with loud buzzing. The amp was supposedly dropped before the buzzing started. One of the 2200uf, 40W filter caps was loose. Pulled the board and replaced both caps and noticed the solder pad on the loose one was broken. Repaired the broken pad by soldering the cap lead to the trace and am getting continuity to the ground. Also noticed a couple of other loose Ecaps and resoldered these. Still getting the loud buzzing. Went over the PCB with a magnifying glass and did not see any other loose or cold solder joints. Still getting bass guitar signal through the amp but the buzzing is too much. Any other suggestions? I have attached the schematic. This is the closest schematic I could find. This schematic shows 2 4700uf filter caps but the ones I pulled are 2200uf caps.
Thanks,Dan

[shooter]

buzz happens with NO signal?


either way, drop testing an amp is a last resort 


start with all the VDC volts n look for the BUZZ riding on any of them
IF clean;
scope the signal path with NO signal looking for the buzz
split the circuits with the "outputs" before the PA section


it's still early and sunny and 70 and, that's the best I got

[acheld]

Not familiar with that model -- is it a combo?  Could the speaker have been damaged?   

[dpm309]

It is a head model. I get the buzzing with or without a signal. Unfortunately I sold my old Tektronix scope last year so I have no way to trace the signal.

[acheld]

FNIRSI DSO152.

I bought one of these for $23 on Alibaba.   Took a couple of weeks to arrive, but it works a lot better than you might think.

Also available on Amawho, more expensive, but will arrive quicker.

[dpm309]

archeld,I looked at a couple of these inexpensive scopes but was not impressed with the reviews. Now that you have tried it, I will give it another look. Noticed last night that my solder pad repair is not connecting to the ground. Will try to resolder it today and hope that does the trick.

[shooter]

solder pad repair is not connecting to the ground.

no ground connection is typical of "buzz everywhere"

[dpm309]

You are correct. I resoldered the pad repair and am now getting continuity. Amp is now working without any buzzing,etc. I am hoping this is the last Trace Elliot SS bass amp that I have to work on.

[shooter]

I am hoping

I know it's hard, but you can say NO!!!!
I did on all the Marshall n fender CCP PCB amps

[dpm309]

Yeah, I know. Repairing these for a friend of mine who is a great Luthier who has been buying and selling these old TE bass amps. Rather work on older Fenders etc with no PCBs.

[shooter]

I fixed my friends Marshall twice, at the time he was gigging 3 nites a week, at that age where lugging his twin wasn't fun.
i wouldn't charge labor, just parts, maybe even barter those.  When he showed up a third time in a year, I said "I'll get it working, you SELL IT, or next time, I want $500 cash, BEFORE i even look"
He took my advice on both a small "old" tube amp that could be mic'd AND selling the Marshall.