Static Type sound When I Turn the Amp On.

[matt1969]

Hello.

I been trying for a while now, off and on, to fix the issue I have with my Marshall Superlead. The issue I'm having is when i first turn my amp on, It makes a static sound for a about 30 seconds or so and then goes away and stays away once it is warmed up.

It does this with no guitar or cord plugged in.
controls do nothing to make it louder of softer.
Tried different speaker cords / cabs
Cleaned all pots, jacks, switching jacks & tube sockets.
I chop sticked (probed around) everywhere and can not seem to reproduce the noise- at least not yet anyway.
Tried different tubes both pre and power.
Re-flowed all solder joints at the tube sockets & input & output jacks

I'm about to try freeze spray to see if I can reproduce the noise once the amp is warmed up.
After that, I guess I need to lift of the board and check for bad solder joints and traces.

I'm just about out of ideas. All of the filter caps are new and I also checked their solder joints.

Any other things I might want to look at that i missed?

[xtian]

Jumper across the standby switch to eliminate it as a suspect.

[matt1969]

Thank you!

[matt1969]

I found the problem. So I think. There was a loose solder joint under the board. I finally pin pointed it after chop sticking for the third time. I have the board lifted up so I fixed that. The solder pad had lifted off of the PCB.

While I'm at it, I'm going re-flow all of the solder joints. Keeping my fingers crossed. Normally when I find a problem while troubleshooting, It's not what's causing the problem, it's something else! Ugh.

Also I noticed the amp lost some its muscle (gain) so hopefully it'll fix that too.

[matt1969]

Yep! it was a loose or bad solder joint on my amp's PCB.