Hi
I'm having some trouble with my Mark IV - hoping someone can help point me in the right direction.
A long time back, it crapped out on stage...some smoke came out of the transformer and the sound went to dirt. Had it repaired/retubed at the time, and it worked, but it never quite sounded the way I liked it. Meanwhile the repairman closed up shop and I could not contact him - he just disappeared. I used other amps a lot more over the following years, and eventually stopped using it at all [part of that being that I wasn't gigging anymore]. I always thought the IV cut through well with a band, but at home in an apartment it's a little less useful
Fast forward to recently, I really wanted to get it back into my setup, so I fired it up, and it made almost no sound at all. While I was letting it sit for several minutes, there was a pop sound from the speaker and a slight burning smell. Turned it off [fuse did not blow], put in some older but not dead power tubes I had sitting around, swapped a preamp tube around here and there, and got some sound, although anyone that has a MkIV knows something is wrong, because I was testing at master volume 6-7 in the middle of the night, and didn't wake anyone up. So there is a volume problem. Bought all new tubes just to eliminate that as a suspect...new preamp tubes were even worse, and I tested 4, all the same JJ ECC83s. the new JJs completely kill the volume [and distortion] if I put them in V2 or V3, although they work ok I guess in V1. The funny thing is, the older tubes I had hanging around at least *work* in V2 and V3, even if the volume is still low, so I'm not sure how to troubleshoot the JJs. But something tells me they can't all be bad...maybe it was the smoke that gave me that clue ;-) No smoke or any pops etc at all since then, and it has been somewhat playable with the mix of old tubes, but it's not loud.
So I know something needs to be fixed, but I want to be able to understand the problem, even if just to explain it to the techs. Anyone have a guess at what might be the trouble and what troubleshooting I might be able to do to get closer to the answer?
Really appreciate any pointers anyone can give me.
Thanks
I'm having some trouble with my Mark IV - hoping someone can help point me in the right direction.
A long time back, it crapped out on stage...some smoke came out of the transformer and the sound went to dirt. Had it repaired/retubed at the time, and it worked, but it never quite sounded the way I liked it. Meanwhile the repairman closed up shop and I could not contact him - he just disappeared. I used other amps a lot more over the following years, and eventually stopped using it at all [part of that being that I wasn't gigging anymore]. I always thought the IV cut through well with a band, but at home in an apartment it's a little less useful
Fast forward to recently, I really wanted to get it back into my setup, so I fired it up, and it made almost no sound at all. While I was letting it sit for several minutes, there was a pop sound from the speaker and a slight burning smell. Turned it off [fuse did not blow], put in some older but not dead power tubes I had sitting around, swapped a preamp tube around here and there, and got some sound, although anyone that has a MkIV knows something is wrong, because I was testing at master volume 6-7 in the middle of the night, and didn't wake anyone up. So there is a volume problem. Bought all new tubes just to eliminate that as a suspect...new preamp tubes were even worse, and I tested 4, all the same JJ ECC83s. the new JJs completely kill the volume [and distortion] if I put them in V2 or V3, although they work ok I guess in V1. The funny thing is, the older tubes I had hanging around at least *work* in V2 and V3, even if the volume is still low, so I'm not sure how to troubleshoot the JJs. But something tells me they can't all be bad...maybe it was the smoke that gave me that clue ;-) No smoke or any pops etc at all since then, and it has been somewhat playable with the mix of old tubes, but it's not loud.
So I know something needs to be fixed, but I want to be able to understand the problem, even if just to explain it to the techs. Anyone have a guess at what might be the trouble and what troubleshooting I might be able to do to get closer to the answer?
Really appreciate any pointers anyone can give me.
Thanks