After about an hour of use 65 115 volume fluctuates

dsteinschneider

The studio here is the second owner of this 1979 65 115. The amp sat unused for many years in a storage unit.

It was "bench tested" by someone here in Connecticut who has a reputation as a guitar amp tech who can solve difficult problems. He returned the amp saying he couldn't replicate the issue.

We're hoping someone on this forum might be familiar with this behavior.

Can anyone recommend a Music Man repair tech anywhere in Connecticut or Westchester County?

Thanks in advance for any advice on this problem

EDIT - We're taking it to Jeff Stileau at Shoreline Electronics and Sound in Clinton, CT

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mm210 Thu, 03/07/2024 - 04:43

Clean the tube sockets, pull the IC's and clean THOSE sockets. THEN start with diagnosis. If the sockets aren't it, it might have a bad/loose solder joint. Chop stick after warm. Then start looking at the caps. Mechanical items usually go first, in my world. Mike.

mgriffin155 Fri, 03/08/2024 - 11:48

I would also do as Mike suggested. Clean all IC and tube sockets 1st. -mgriffin

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RD112 Fri, 03/08/2024 - 16:25

There are two zener diodes that control/hold voltage supply to the OpAmp chips to exactly 16-volts. The zener diodes are heat sensitive and deteriorate with age…so they might be fluctuating…and need to be replaced.

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