Marshall Lead and Bass SS JMP 2195 issues

[henter2017]

I just googled the name along with schematic on google images and it popped up!
as usual with chinese parts it comes rebranded but is the same one:

Douk Audio MX50
MX50SE LJM 2015

http://nazya.com/freeshipping/single...orig_desc.html

[J M Fahey]

Thanks.
I think I found it on DIYAudio, somebody was simulating it:

[olddawg]

I looked at the all the photos of the board. It doesn't look THAT bad to me. It seems to be a milspec type board (as apposed to the resin/paper types that burn into conductive charcoal). If you clean it up really good with solvent/alcohol, use flux, and use the appropriate lead wire, I don't see a problem repairing it. If vibration is an issue seal the underside with 5 minute epoxy AFTER the repair is complete and tested. I've repaired much worse on a daily basis back in the day. A useful tool is one of those fiberglass tipped abraiders in a pen package we all used to have for scrapping the lacquering off of traces. Just take your time and do a precise and CLEAN job of it.

[henter2017]

Hi Folks, got the power amp today, and getting in paper the plan work I have a question regarding the Input wiring, as its a +/- Input, but in the marshall schematic I can only see a single output to poweramp...

Anybody could help me understand how I should be wiring the input.

(The old poweramp components will be snapped off and the new board installed in the chassis, with the PNP/NPN transistors wired up to the old heatsink)

[mozwell]

the power amp - input goes to EARTH "C" or the cathode of ZD1

[henter2017]

thanks a lot! So i guess I can jump it to GND in the sale board and connect that direct to the chassis!

[henter2017]

All sorted and sounding great now! Thanks to everybody that helped me out sorting this Old beast out.
I mounted the new power amp board to the chassis, the transistors out of it and mounted to the huge heat sink at the back of the chassis and removed the whole old poweramp components.

[J M Fahey]

Congratulations

I guess now we all deserve a little YT demo

[henter2017]

sure! hehee, I will try and get someone that actually plays to make some noise while I record it next time I jump to the studio!