Let's Get Technical > Troubleshooting Problems

4ohm Resistor Across C131 & D38 ?

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red2203stack:
Good Morning,
I'm getting ready to recap an all original unmodified MP1 with a REV E board. Located at the positive lead of C131 (OEM; 3300uf 25v) is a 4ohm resistor that jumps to D38. Has anyone ever seen this in an original? What's it's purpose, to act as some kind of snubber to prevent poping at start up? Any replies greatly appreciated.

Joe

Dante:
Hiya Joe, Glad you made it in here, welcome to the DEPOT!

I'm sure somebody will chime in with a response to your question very soon, I'm not the guy to ask. Best of luck with the project!

Dante

red2203stack:
Thanks for the welcome Dante, been lurking for years. There's so much good info in this forum I never had to post before.

As far as this project, gonna keep it simple with all original values.

Replace front input jack
Partial electrolytic recap
Change 1N4007 rectifier diodes to UF4007
LED Upgrade
Replace pots
Battery receptacle upgrade
Check/clean/refresh solder joints & PCB & jacks

Looking forward to getting this bad Larry plugged back in.

red2203stack:
Found a chip in the circuit path above the diodes. Not sure if it was intentional. Also a green jumper wire. Everything in this unit appears to be original from the factory. Still not sure the purpose of the 4ohm resistor.

rnolan:
Hey Joe, welcome to the depot.  :thumb-up: :wave: you may want to pick up some bits and pieces from MJMP (http://www.marshalljmpmodshop.net/miscellaneous_parts_and_replacement_tubes.htm) and he can probably enlighten you on the resistors purpose.

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