Cleaning power tube sockets

anomaly

anomaly

Well-known member
I keep getting this recurring problem with my Mark IV. I get this popping, crackling noise when I take it off standby which last for about 5 seconds then it's fine. I previously cleaned the tube socket that has the problem with contact cleaner and I thought i had it pretty much fixed, but now it's doing the same damn thing. Is there a better way to clean the contacts?? like maybe a Q-tip with contact cleaner or something?? I've cleaned this socket SO many times now and it's still doing this noise... makes me think something else may be going on. Everything looks fine though, so IDK??
 
Also recently when in Class A mode I blew a power tube in this same socket. Replaced it and it was fine, but I thought that was quite the coincidence.
 
Also, another problem. When in the Triode setting, the amp hums, but it is quiet as a mouse in the Pentode setting. The hum is not overbearing but still loud enough to annoy when playing at low volumes.
 
The pentode / triode dependent hum should be a tip off for anyone familiar with the IV.
Did ya post in the Boogie forum? Lots of Boogie tech geeks over their.
 
[ Donnie B. ] said:
The pentode / triode dependent hum should be a tip off for anyone familiar with the IV.
Did ya post in the Boogie forum? Lots of Boogie tech geeks over their.
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Ya, i posted it up on the Boogie Board a long time ago (about that hum) but I got nothing. Seems no one knows what the problem may be?? I'd like to fix it myself if I can. I got soldering skills. It's not a huge deal though, cause I use Pentode mode 90% of the time, it sounds a little bigger. This problem with that noise when I click it off standby though, that bothers me. Makes me think a dirty connection that simply won't clean or something worse.
 
anomaly said:
Ya, i posted it up on the Boogie Board a long time ago (about that hum) but I got nothing. Seems no one knows what the problem may be?? I'd like to fix it myself if I can. I got soldering skills. It's not a huge deal though, cause I use Pentode mode 90% of the time, it sounds a little bigger. This problem with that noise when I click it off standby though, that bothers me. Makes me think a dirty connection that simply won't clean or something worse.
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Interesting read. Dr. Z says triode hum is normal in this particular amp.

https://ztalk.proboards.com/thread/82819/hum-triode-mode
A lot more techy, but again normal. Check page 6.

https://dalmura.com.au/static/Hum article.pdf
 
Thanks for the that. So it's normal in amps with a pentode and triode switch to hum a little bit in triode.
 
anomaly said:
Thanks for the that. So it's normal in amps with a pentode and triode switch to hum a little bit in triode.
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No... it's not normal. All my Marks, including the IV are dead-quiet in either pentode or triode mode. If you're sure the preamp tubes are good... and properly tested... just replace the power tube socket. Why bother trying to clean or fix a $10 part? Makes zero sense.
 
Wizard of Ozz said:
No... it's not normal. All my Marks, including the IV are dead-quiet in either pentode or triode mode. If you're sure the preamp tubes are good... and properly tested... just replace the power tube socket. Why bother trying to clean or fix a $10 part? Makes zero sense.
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I'm 90% sure it has something to do with the one outside socket. I've tested various tubes (as well as pre-amp tubes) with the same results... also, when I move that tube around a bit it crackles and pops so there's something wrong there.

I live in the middle of nowhere with no access to parts or a decent tech. I would do that if it was an option for me. Plus, installing a new tube socket might be too much for me, IDK, i can solder fine but I'm nervous about the voltages.
 
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Honestly I am comfortable working in amps, then I cracked open a mkiv and decided not to do it again after that. There is a lot of shit going on in that chassis. It's no JMP in there.

Call the guys at Mesa. They are usually excellent and have the replacement parts you need. Or send it in. It's old enough to be due for maintenance anyways.
 
How do you tighten the pin contacts that the tube pins go into?? Do you just push them down with something?? I don't get how to do that??
 
Fuck I hate tube amps, it's time for me to go back to solid state Randall's. Anyone have a Randall rg100es they want to part with?

I'll make them a deal, they can have my Mark IVa/b (rackmount head) that has some minor issues but otherwise sounds killer, for a Randall RG100ES in good working order + a little cash. Talk to me. I know some of you guys have Randall's.
 
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anomaly said:
How do you tighten the pin contacts that the tube pins go into?? Do you just push them down with something?? I don't get how to do that??
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Yes. You can just push them back with a small screw driver... but you need to discharged the filter caps and make sure there is no stored current in the caps. If you're not experienced or comfortable, find a local tech or someone with some soldering, radio, or electronics repair experience.

Swapping out the power tube socket is pretty simply and straightforward. A Mesa MKIV is not a space shuttle control panel. Way way way over stated. You can order the parts direct from Mesa as well.
 
I would make sure there's good tension in the sockets too. Could be that the retainer springs are opened up and need tightened. Loose connections will do that too, or even cause a tube to replate.
 
Been dealing with same hum issue with my 2008 era Mark IVb combo. Narrowing in with my tech that there is a faulty pentode/triode switch which causes an outer tube fault and then a screen resistor burnout. There should be NO hum in triode mode. I know, because when it’s working right, the hum is non existent. Hope this helps.
 
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