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If you ever wondered what red plating valves look like, check this out!
Great photograph, borrowed from another forum. This chap is having an issue with his 100 watt Blackstar S1. No bias?
If I saw valves like that in one of my amps, I wouldn't be taking a photo ... I'd be turning the amp off pronto!
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Comments
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
Yes,
Most likely the cable from the middle board to the OP valve PCB but if so it will be the first time I know of it happening on an S1. I have had it work loose on an HT-100 and routinely cable tie the lead to prevent it happening again.
If the problem is in the bias circuitry I strongly advise getting it back to Northampton because the bias is tied up with the DPR circuitry and that is not a job for the amp beginner. But again, there is no history of trouble with the amps in that regard as far as I am aware.
ICBM would also be on the case I am sure!
Dave.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
Bandcamp
Spotify, Apple et al
Don't talk politics and don't throw stones. Your royal highnesses.
My Marshall MA50 redplated during it's first gig. The head started to glow a mystical orange colour whilst the volume dropped.
It's certainly the most spectacular thing that amplifer did in it's short spell with me. Certainly none of the noises that came out of it were decent
So I bought a new set of 4 Mesa valves.
Two of them redplated on install, so I put the two non-redplating old ones back in (if it's an amp issue, there's no harm in that), and it's been fine ever since. Brand new valves redplating. Grr.
Was it the same two valve positions in the amp? And was it two at the same end?
If so there probably is an intermittent bias feed problem to those two valves. If it wasn't the same two valves, it was probably only one each of the red-plating pairs. The two valves in each pair are linked so a fault in one can often make the other one red-plate as well, sometimes worse than the actual culprit.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
You did mention bias resistors re: the Nomads, so it could have been an intermittent fault with one of those, perhaps. I might get them replaced as a service item at some point if that's a likelihood.
Edit: they were at one end, too. the pair nearest the middle of the amp (farthest from the power switch) iirc.