Hi all,
So I just noticed my Mark iib head seems to have developed some sort of intermittent issue (it has not been used, maybe at all, in 5 years. Although all caps, etc look ok).
Seems to be intermittent in that I can't recreate it when I want to (although it MAY have to do with being moved around. As I was sliding it out of the chassis a few minutes ago, it came back.. And hasn't disappeared since I haven't moved the amp but have turned it on and off a few times), but it seems sometimes the volume decreases a little bit, there is a hum/buzz, and there is a crackle whenever a note is played (the crackle sounds the same no matter what note).
Digging through all the posts on here, I never knew about that Preamp Out/Power amp in on the bottom of the chassis. Plugging a cord from there into a small practice Marshall jack-in, the Marshall sounds fantastic. So I am assuming it's an issue with the power amp portion? The 2 power tubes are Sovtek (I believe they came with the amp when I purchased it), and I can't recall if this noise happened when I mothballed it. I swapped them with each other, same intermittent issue. Tapping them does nothing.
Unfortunately I do not have other power tubes to try. Any suggestions before I bite the bullet on those? Are there any other common issues that cause a similar issue? I found a bunch of threads on here, but most remain unresolved.
Thanks gents!
So I just noticed my Mark iib head seems to have developed some sort of intermittent issue (it has not been used, maybe at all, in 5 years. Although all caps, etc look ok).
Seems to be intermittent in that I can't recreate it when I want to (although it MAY have to do with being moved around. As I was sliding it out of the chassis a few minutes ago, it came back.. And hasn't disappeared since I haven't moved the amp but have turned it on and off a few times), but it seems sometimes the volume decreases a little bit, there is a hum/buzz, and there is a crackle whenever a note is played (the crackle sounds the same no matter what note).
Digging through all the posts on here, I never knew about that Preamp Out/Power amp in on the bottom of the chassis. Plugging a cord from there into a small practice Marshall jack-in, the Marshall sounds fantastic. So I am assuming it's an issue with the power amp portion? The 2 power tubes are Sovtek (I believe they came with the amp when I purchased it), and I can't recall if this noise happened when I mothballed it. I swapped them with each other, same intermittent issue. Tapping them does nothing.
Unfortunately I do not have other power tubes to try. Any suggestions before I bite the bullet on those? Are there any other common issues that cause a similar issue? I found a bunch of threads on here, but most remain unresolved.
Thanks gents!
