Marshall JCM2000-DSL-100: board replacement

[Jim-Analog]

Greetings,

I went through all the older threads that mentioned JCM2000 amps and rather than reviving an old one, decided to start fresh. This is the first of this series of Marshalls that I've worked on (we don't get many PC amps in our shop). Anyway, a good client brings in his amp, problems with output section over heating killing tubes on one side of the P-P and some other issues I didn't like the looks of. I do a bunch of research/reading and find there are MANY issues associated with these amps: incorrect resistor values, neg tempco resistors, traces too close, conductive board material, etc.. Rather than trying to fix these various problems (this specific amp seemed to have most/all of them) and then not feel 100% confident about sending it out with a pro client, I ordered the newest version "tube" board that is *supposed to* rectify all of the known issues.

Upon receiving it, I noticed one of the previously mentioned frequent failure items, the bridge rectifier for the small signal tube heaters is exactly the same as the old version; still using the same 6A part flush mounted to the board. I replaced it with a 10A part and raised it up off the board surface about 3/4".

Though not related to the board but also found to be frequently problematic, I took care of the speaker jack trace routing that had relied on the normally closed contacts of the 16R output jack to supply the ground to all the other jacks.

SO, my questions are............for those techs that have replaced the board, were there any other areas to attend to before sending it out? Has anyone had a call back that involved the updated board? Any new problems found since board replacement?

Another mentioned problem were PC traces considered too light gauge for the tube heater string current draw. Has that been found to be adequately improved on the new version board or is it still an issue that needs to be addressed with bus wire and solder?

Thanks very much for any input, I want to be sure I send out a reliable product with my client, so he doesn't end up with any failures that could have been prevented while the amp was in the shop.

Regards, Jim