Marshall 9200 problem. Amp Gurus pls help



I have a Marshall 9200 poweramp (Dual mono-bloc) that I am having problems with. Channel A works fine, but when I turn on Channel B, I get no output, but rather I get this low pitched buzzing sound that becomes louder and louder. (Both channels work independently of each other, as in Channel A runs 4 6L6GC tubes and Channel B runs another 4 tubes)

Also, Channel B's tubes glow blue when it is turned on. (I never turn Channel B longer than 30 seconds after that buzzing sound starts) I was wondering whether it was a blown tube or whether it is something more sinister at work, i.e. a blown transformer.

FYI, the amp doesn't trip the fuse, but rather the tubes just immediately glow blue, like the gas in the tubes is on fire or something.

Thanks for your help guys.

darmowe dzwonki na telefon

edited 30 Oct 2020 at 06:09 AM

Leffler Hirthe

asked 26 Oct 2020 at 07:48 AM

Leffler Hirthe
Answers: 1


Hello Leffler,


Regarding your 9200:

A blue glow within the tubes indicated one of two things:

  1. Either the tubes are gassy – Which would also explain the increasing hum.
  2. Something in the output stage is drawing excessive current. (Possibly the gassy tubes)

In either case we would recommend the  amplifier is  looked at by a qualified and experienced engineer to establish what is wrong.


Kind Regards

Marshall Support

answered 27 Oct 2020 at 12:07 PM

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