My Music Club had a Marshall Amp (JCM2000 DSL 401) which wasn’t able to deliver any sound, also it was working a few weeks ago. This Amp was really a good one, but the club have already had to face multiple repair bill, and the hardware guy was about to give up…
A quick google search with “DSL401 repair” and “DSL401 failure” give me plenty of information’s, all the schematics, and some tracks to follow. The most frequent failure seemed to be rectifier bridge premature death. http://www.marshallforum.com/marshall-amps/3505-dsl-401-repair-not-repair-question.html
After disassembling the Amp, and the front face of the Head, i searched the famous bridge component, the solder pads and the PCB power lines
Bingo, the solder behind the bridge have burned, and the power lines showed burned pads too!
All i have to do now, is to replace the faulty component, named BR102, a 200V 10A. I had the choice to get new one, and install it at the same place, with a few space between the PCB and the component, for heat dissipation.
But i decide to use more “ruggedized” component, a 200V15A bridge rectifier, named: GBPC1502W
It has the same orientation, but not the same size, so you have to bend the leads, and avoid the orange cap.
I also re-soldered all the power lines pads, burned or not burned, in order to avoid faulty soldered component.
The new bridge rectifier was put on direct test 2 hours long (orange glows in the middle of the brown supports), and was just warm, not hot!!!
In order to get things less hot, i re-bias the DSL401 with a level of 1V, as it was previously set to 1.24V. I didn’t want to change the resistors, cause i didn’t want to introduce more than a change at a time!!!!
So, after one hour of intense tests, all was screwed alltogether, and the Amp brought back to the practice studio…