Mesa Boogie Studio 22 Low Output (Unless FX Loop Patch)

[misterc57]

Picked up a Studio 22 combo (this is not the 22+ version, it does not have the 5 band EQ). It has low output until you jump the FX loop with a patch cable.

I cleaned all the pots and jacks with Deoxit with special attention to the FX loop jacks. Was hoping that would fix the patch cable issue but it did not. What is the typical reason for this issue and remedy? Are new jacks the only cure, or is it a poor connection issue that can be mechanically corrected, or something else?

This amp also had its ground pin removed at the power cord plug and has a broken off volume pot, both of which I will be replacing.

Thank you.

[Mick Bailey]

Meter across the switching contacts of the FX loop -they should read close to zero. Short your meter probes together first and subtract that from your actual reading. Deoxit can only help to a certain degree. Are the contacts accessible?

[misterc57]

See picture. I have about 52K at either of the black to red wire. Only if "both" jacks have a patch cable inserted, I then read nearly zero ohms.

If I pull all the jacks out and get to the other side can I burnish or bend the contacts for a better connection?

[g1]

You'd probably need to bend it. Put a plug in it and push down on the leaf contact at the tip end. Remove the plug and check that it is now zero ohms from red to black wire.
It won't be a very reliable repair and a new jack is the best solution.

[misterc57]

That, a squirt of Deoxit, and a bit of scraping with a tiny flat blade screwdriver brought me down to 1 ohm.