Hey guys I recently bought a second hand Peavey Bandit 112 Red Stripe and its seems to have a realy weird problem. I took it into the shop to have it fixed, it came back sounding great until I took it to band practice and had to crank it a little, then the problem seemed to start up again. The tone, especialy on the distortion channel, seems to have a bit of a weird buzz to it and when its cranked to higher volumes the sustaine seems to completely fail. If I take my hand off the strings or pluck it softly the amp makes no sounds but if I pluck it harder it suddenly comes out with a huge wall of volume, also the higher notes fade out realy quickly and the vintage setting hardly registers when I play and fades out quickly. I dont know if I just dont know how to use the amp settings properly or if there is something just faulty with the amp. The reverb channel has been removed so I dont know if that has anything to do with it?

Any help will be greatly appreciated
I had a similar problem on my mini PA when the power supply failed on one of the output transistors. You'll have to get it fixed again - just ask to run a proper test to be sure the problem is gone once and for all.
I've seen similar problems with cracked solder joints on the input jack or control pots.