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Hello, new to the forums I dont know very much about tube amps, this is my first tube amp. Marshall jcm 2000 dsl 401 combo amp. A week ago the volume faded out and a few seconds later it came back, now the volume is gone. it powers up but when i switch on the standby nothing happens. the only thing ive noticed is when I look in the back the 4 slim tubes ( im guessing those are the power tubes) have an oragne glow at the base, the 4 smaller wide tubes arent lit up at all. Ive been searching the web for days trying to figure out what that means.. do I just need 4 new pre amp tubes? or was a fuse blown? I dont even know how to check the fuse or what kind of pre amp tubes this amp takes. A good starting point appears to be checking the fuses, I just cant find any instructions on where to find the fuses to check, any help would be appretiated. I typed this quick so please excuse spelling, thanks
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On some preamp tubes it's hard to see the glow, but if you grab 'em you'll feel the heat. -
On the DSL combos, this is usually caused by the bridge rectifier to the DC filaments on V1/V2 going south. Its easy enough to diagnose. Simply leave your DMM on the 6.3v DC output after the rectifier and associated caps.Comment
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Hi, I have a JCM 2000 DSL 401 that has a similar concern. It will fade out just like you turned on the standby and a few seconds later it will fade back in. This will happen 3~4 times and then the volumn will not come back. Turn it off, let it cool, and the process starts over...
Any ideas?
Byron LordByron444@gmail.comComment
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Hi, Byron. Welcome to the forum!
I think you would get a lot of responses if you start a new thread with your problem. It's something that's been dealt with here from time to time.Comment
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Your answer is in the post directly above yours. Of course it could be other things as well, but usually, it's the bridge rectifier/connections in these amps.Originally posted by Byron View PostComment
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