Let's Get Technical > Troubleshooting Problems

MP1 v 1.38 no sound can someone help me out?

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Wormwoody:
I have an older 1.38 MP1 and it whaled but a bit noisy. So I got a good soldering iron and went to town installing the noise kit, some diodes, caps, battery mod, and a few other things from MJMP. Now I don’t have sound from tube clean or tube dist but SS works. I don’t know what I did and am wondering if someone can walk me through a troubleshooting process???

Thanks!

Iperfungus:
The one and only: MJMP!  :thumb-up:

rnolan:
Hey Wormwoody, MJMP will no doubt help you get it sorted.  Good news that the SS works.  My guess is the signal isn't either getting into the tube circuit or out of it, or there's an issue in the tube circuit.
Did you do any work on the tube board ?
Are all the tube board connections to the PCB how they should be ?
Are the tubes ok ? and are they lighting up ?
Did you change the transformer ?

IIRC the SS input/circuit basically bypasses the tube section, also remember the OD2 setting controls the amount of compression in SS mode.

Iperfungus:
I agree: looks like something failed into the tubes board.

MarshallJMP:
Rnolan already made some good points, start there. Do the tubes light up? Do you have high voltage on R1 and R4 on the tubeboard?

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