Marshall JCM800 100w split channel problems

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jimmy74
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Marshall JCM800 100w split channel problems

Post by jimmy74 » Sun Feb 13, 2022 10:15 pm

Hi folks,
I've retubed, recapped and rebiased an 88 jcm800 split channel 100W amp and it was working fine but soon after the owner brought it back saying that the drive channel wasn't working. When I switch channel infact there is very low volume on the drive channel almost as if one of the tubes is blown. First question which tube or tubes are for the drive channel? Second question while I was working on it I noticed some caps installed under the board which looked like new additions but of the same type used by marshall back then. And also there were 2 ceramic disc capacitors on one of the 12ax7 sockets (if I remember correctly V3) which looked original but were not on any of the schematics or photos I could find online.

I can get some photos if necessary
any thoughts?

thanks
J.

danman
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Re: Marshall JCM800 100w split channel problems

Post by danman » Mon Feb 14, 2022 6:56 pm

Forum traffic has slowed to a crawl these days. Many of the members are now active over at the "Marshall Forum". I would try over there to get an answer.

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