Peavey Bandit 112 Transtube crackling

[ApeWeevil]

Hi,

I made a thread in this forum before about a loud popping problem with this amp but now I have a different issue. I opened up the amp when I had the popping problem and had a look around for any signs of loose connections but couldn't find anything.
After putting it back together the popping problem had ceased but I was left a crackling sort of noise. I abandoned the amp for a long time after that, but now I'd like to finally get it sorted if I can.
When I'm playing, especially as I increase the volume or play lower notes, the amp crackles intermittently. The noise is the same whether I have the amp cranked or the volume at zero and I tap the amp, apart from it lasting longer and being more 'violent' if I play louder or hit it harder.
It seems fairly obvious this is an issue with a connection somewhere, but I'm fairly clueless about how to go about checking exactly where my problem is. I did take a hard look over the main PCB for any obviously loose solder joints but came up with nothing. I have schematics for the amp if that helps, but I'm just wondering how to go about checking exactly where it is and what the fact that it's independent of volume/gain indicates.

Any help would be greatly appreciated.

[52 Bill]

It seems that you have already figured out that there is something loose, but now you need to find it. The only suggestions that I can give you will require that you have the amp opened up and powered up.

If you feel confident enough to work this way, you can try poking around and tapping different parts and sections of the PC board to see if you can isolate the area where the loose connection is. Use a wooden or plastic stick and keep away from the live AC sections.

Remember to check any and all push on Molex connectors. And also remember that it may not be a bad solder connection, it might be a broken wire lead on a component that is just making contact above the PC board.

[Jazz P Bass]

Peavey troubleshooting

If you want to know exactly where the amp is failing, then you have to troubleshoot the amp.
Divide the problem.
Is the problem at the output?
If it is, then look at the middle of the amp circuit.
Keep dividing down until you isolate the problem to a specific section.

If it was on my bench, the first thing I would do is resolder all of the major components & all of the connectors. (peace of mind approach)
Good Luck. Don't let it win.

[ricach]

I just took in a Bandit that had all kinds of problems. From popping, crackling to most times just stops working. First step was to clean all the pots ..... that was it. Fixed everything. I took ProGold and a syringe and made sure each pot got a decent dose. You'll need to take the PC board completely out of the amp because you'll need to turn it over to access the opening in the pots.