Quote from: Lobsterjoe on January 10, 2024, 02:47:17 PMJust got an '06 Trademark 60. At power-on, there are continuous popping and whooshing noises. Consistently, it goes away after about six minutes.
Power cycle and the noise returns but then lasts less than a minute; unless the amp's been powered for an hour or more-then it's fine after restart.
All other functions work and amp sound normal except for addition of noise.
If I plug guitar into the effects return, the noise stops and guitar sound is fine.
Cleaned all the jacks, visually inspected PC board, jumpered the FX loop jacks (no effect on noise).
Channels settings, boost level and reverb level don't affect the noise level, but master EQ does. The character of the noise doesn't change-just how loud it is proportionate to the EQ cut or boost.
Tech 21 was responsive to my inquiry and said they haven't seen this before. Suggested I send it in. Being in California, the round trip shipping even for chassis only will be almost as much as the bench charge. Reminder: other than switches and some caps/IC's, most of the components are SMT. Comments welcome.
Given that the noise is modified by the tone stack, that means that it is happening before this point in the circuit. Starting there (at the tone stack), working your way backwards towards the input jack. Something between here and there is either fried, or has a cold solder. Odds are it is a cold solder. Careful inspection of the potentiometers as well as any caps and ICs that are through hole components in this area (between input jack and tone stack) and I think you'll find the issue.
You can also share close up pictures of the board and we'll see if we can help.