Marshall 6100LM 30th Anniversary Tube Amplifier Emergency Repair
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- Опубліковано 26 жов 2017
- WAIT!!! STOP !! Put the pitchforks down!!!!
This video is a RARE departure from my usual work. I was given a specific task to get this amp to stop the output tubes from exploding. Period. with a minimum of work and modification to that end. NO MATTER WHAT!!!!! So save it... I have pointed out all sorts of things that I would have liked to replace on this; it was not to be.
Since this was already completely off the chain. We decided to do a completely unedited episode, aside from some diagrams i added later only for circuit context.
Enjoy!
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Hey Guys, for anyone with the same crazy hot bias issue on a Marshall 6100LM....
We had one of these amps in the workshop with the same problem, melting output tubes. Traced the fault to C211 which is a Class X safety capacitor, these are guaranteed to fail open which is what happened.
Replaced both C211 and C212 along with much of the bias network since I was in there anyway and happy days🎸
Hope this helps someone out there!
An amplifier repair tech told me that it was a known problem for the 30th Annv. Amp. Marshall knew about it but did not do anything about it.
I also have the same amp and it has the same problem. Main fuse blows, the valve blows...
How can I fix this? What did you do to repair the amp? Did you replace the resistor R213 with another ? did you replace the capacitors c209 & c210 ?
I have had my pitchfork waving in the air at Marshall for too many years !
please help
im having the same issue, power tubes got wiped out and popped the 4amp fuse, can't bias to range
You never mentioned in the video what you did as a quick fix?
Another good video..............Is that amp directly coupled, or capacitor? Maybe they're leaky....
Hello John, looking at the highlighted diagram I posed you can see that the DC leakage is pulling the bias voltage 'UP' towards ground. They are not the big exploding ones below but the smaller ones in and around the resistor in question. Again, my limitations with the unit with regard to owner criteria prevented me from pulling the board removing the capacitors and measuring them for leakage and replacing properly.
Jordan, I wanted to mention also, your friend is a pretty good musician. I just sold a Craftsman 6L6 mono amp with Am Fm tuner and miss it already. It came out of a console unit. Ugly, but great sounding. My wife was happy, it freed up a minuscule amount of space.............
How funny, IM not the one buying Tube amps, my wife is..... Heathkit equipment however, guilty on all charges