OK, First post here. I wish it wasn't for a problem.
I bought a used Marshall Combo Valvestate VS100 amp. When I got the amp all was GREAT. Now after a couple weeks of only playing it a few times a week at fairly low volumes it started to act up. When it first powers up all is good, then I start to get a crackling sound after a few minutes while playing. If I tap the top of the amp with my fist it produces the same crackle. If I keep playing for about 5 - 10 minutes it just cuts out and makes no sound at all (no guitar or anything). I also notice that the power light dims when it cuts out. If I turn the amp off, I get a real loud POP when the power switch comes out. I can turn the amp right back on and it works again but starts producing the crackling sounds.
I swapped out the tube for a new one but it made NO DIFFERENCE...
I'm going to video tape it and post a video hopefully later today. In the meantime if anyone has any suggestions, please share.
Thanks so much in advance for any help.
I shot some video to give you an idea of what's going on. You can view it on YouTube
YouTube - Marshall VS100 Problems The problem spots are at about 1:40 new problem seems to have developed and can be heard about 1:50 in. The POP turning it off can be heard at about 4:15 and 4:53.