Guess what?

Robert Herndon said:
I had a JTM 30 that was notorious for overheating. I never could correct that problem.
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Yeah those and the JTM60 had a terrible heating issue where the tubes were mounted horizontally and they didnt put a vent on the top of the amp to let it breathe, as heat was rising straight to the top. They were 5881 tubes and biased kinda hot anyways, plus they mounted the Bridge Rectifiers directly onto the PCB, so they would just cook them.

I seen some pics of guys who initially built like a heat shield out of aluminum and placed it between the tubes and the chassis, then mounted the rectifiers up off the board. Marshall even later made a heat sink that wrapped around the tubes, but like the infamous JCM2000 bias drift, they didnt offer it as warranty or recall: you had to buy it of course.

They ended up discontinuing the JTM30/60 line over this and rebranded it as the JCM600 series the same year the JCM2000 debuted, but had switched to EL34 tubes and changed the look of the amp to where people didnt like it nearly as much compared to the classic grill cloths of before. It quickly ended too, which is a shame cause the JTM series were really nice sounding and the JCM600 was great too
 
mcblink said:
I have noticed this myself my man lol

Maybe some of my my ancestors shagged some of your ancestors somewhere along the line? Lol
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If you do need help to remove replace the bias pots, PM me and you can send it over.
It's going to take me about 10 minutes, and then I can mail it back to you.
You can send that in a padded envelope.
If you need help the offer is open.

Once you get the bias adjust board back in we should run through and make sure everything is working.
Then you can put the tubes in last.

But make sure it's all working First before you try to operate it.
 
Amp Mad Scientist said:
If you do need help to remove replace the bias pots, PM me and you can send it over.
It's going to take me about 10 minutes, and then I can mail it back to you.
You can send that in a padded envelope.
If you need help the offer is open.

Once you get the bias adjust board back in we should run through and make sure everything is working.
Then you can put the tubes in last.

But make sure it's all working First before you try to operate it.
Click to expand...
Duly noted, very much appreciated.
I was beginning to get confident enough to try it myself, but I don't have the greatest stuff to do it with, nor the experience. Just this:

20210416_100509.jpg

Considering that the other resistors are still in transit and with another 5 to 8 days until arrival, I would probably be a fool to refuse your most generous offer. Why should I get in a big hurry to potentially destroy my own parts due to lack of experience?

I will send you the board, the new pots, in a padded envelope.

PM incoming
 
mcblink said:
Duly noted, very much appreciated.
I was beginning to get confident enough to try it myself, but I don't have the greatest stuff to do it with, nor the experience. Just this:

View attachment 63959

Considering that the other resistors are still in transit and with another 5 to 8 days until arrival, I would probably be a fool to refuse your most generous offer. Why should I get in a big hurry to potentially destroy my own parts due to lack of experience?

I will send you the board, the new pots, in a padded envelope.

PM incoming
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I’m glad that you’re going to take him up on his offer! Did you get that solder spool in the hardware store? Plumbing section? I’m not well versed with the “lead free” labeling in relation to the usual kester stuff I’ve been using for years...but....that doesn’t look like the type of solder that I’d be comfortable using in an amp or pedal.
:cheers:
 
Thatbastarddon said:
I’m glad that you’re going to take him up on his offer! Did you get that solder spool in the hardware store? Plumbing section? I’m not well versed with the “lead free” labeling in relation to the usual kester stuff I’ve been using for years...but....that doesn’t look like the type of solder that I’d be comfortable using in an amp or pedal.
:cheers:
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It's a spool I found in LRT's shop. I won't be using this for these repairs. I haven't done anything just yet, because, well, I don't know my ass from a hole in the ground when it comes to soldering. I will have to grab some different solder before I go in for that burned resistor on the main PCB. That particular one doesn't make me as nervous as the PCB for the bias pots does.

Give me a rod of 6011 and I can put all your farm equipment back together though lol
 
mcblink said:
Duly noted, very much appreciated.
I was beginning to get confident enough to try it myself, but I don't have the greatest stuff to do it with, nor the experience. Just this:

View attachment 63959

Considering that the other resistors are still in transit and with another 5 to 8 days until arrival, I would probably be a fool to refuse your most generous offer. Why should I get in a big hurry to potentially destroy my own parts due to lack of experience?

I will send you the board, the new pots, in a padded envelope.

PM incoming
Click to expand...
Dude, that's pipe solder. It's for soldering copper water pipe.
We need to get you some soldering station and electronic solder for your birthday.
 
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