KVH
Member
- Joined
- May 3, 2020
- Messages
- 44
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- 7
It was a negative voltage on pin 5 I just forgot to put the - in place. I did happen to read your post a few days ago. Glad you got it fixed.Shouldn't pin 5 have a negative voltage on it? Sounds like a similar problem that I just had with my 4500 JCM900 that I made a post about last week. But mine has EL34 not 5881 tubes. So I'm not familiar with the different wiring diagram. They should be similar though right?
https://www.marshallforum.com/threads/jcm900-4500-el34-red-plating-run-away-bias-current.122500/
I found my problem by checking for voltage at D1