Freshly serviced jam 800 2203 blew up after 2 weeks... loud buzzing/humming.


Active Member
Jul 16, 2013
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So 2 weeks ago I got my 2203 jcm 800 serviced. The tech replaced the faulty trip pot which fried my tubes, checked the whole amp, and replaced/biased new tubes.

It was sounding great for about 2 weeks and there was a sudden, loud "pop" followed by a very loud humming buzz. The guitar will still play but it is basically overwhelmed by the buzz. The busing fluctuates a bit when the volume know is turned.

I threw in a set of different tubes (after checking for micro phonics) and tried again and the buzzing is still there. I am sure I'll have to take it back to the tech but wanted to know if there was anything else I should check for. I tried different cables, cabinets, and different guitar and its still.

So frustrated with tube amps right now. It would nice to have an amp that doesn't keep failing. I guess thats the price for great tone though.


Well-Known Member
Nov 28, 2010
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Did he replaced the big blue filter caps? I think if they blew it would take out a fuse. Just wondering if that could be it. It can be too serious if the amp still works but there is just a big buzz IMO. Did you look around the board for any loose wires or burnt components? I would play it any more until it is checked out. Let us know what the diagnosis is.

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