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Marshall valvestate 265r repair help needed

Started by macsledge, February 05, 2012, 05:25:37 PM

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macsledge

I repair valve amps and I'm ready to start learning solid state repair. I'm hoping I can learn some stuff on this forum.

This valvestate has what I would call a medum volume hum and low output. I've already fried one of the speakers in it during initial testing and yes there was DC on those leads though there is none on the other pair for the other speaker.

I've pulled from circuit board and tested, with an "Atlas DCA55 semiconductor component analyzer", TR 2, TR 7, TR 13, TR 14 TR 15, TR 16, TR 17, and TR 18. They all test good.

There is approx. 20v DC coming out of the red and black speaker leads. There is no DC om the pther pair of speaker leads.

I'm only getting approx. 12 v DC (+-) at TLO72 and D6 and D7.

Thanks for any help in advance. Gut shots and the schemo are attached.





joecool85

I'm not sure but I will say I'm surprised this isn't a chipamp in the poweramp section but rather discrete electronics.
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Still rockin' the Dean Markley K-20X
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