FX loop issue

[5150Watts]

I just installed my metro fx loop in my 78 JMP 2203. It shows it is receiving 285volts after the decoupling resistor on the loop board so I know it is getting power. When in bypass mode, my amp works fine. When loop is engaged I get very little volume, like the master is on zero. Changing the loops level with the adjuster does nothing to fix the volume. Is the loop DOA? How do I test? I also bypassed the switch and I get the same issue.

[SDM]

Usually this is caused by wires swapped around on the switch or from switch to board. Double/Triple check that all wires are routed properly coming to/from the switch. Check the connections on master and treble pot and loop board ground wire too.

Also possible a shielded wire is shorted out, be sure the shields are correct, nothing melted through insulation anywhere or such. Could of course be an issue with the board, but over 99% of the time it's something like the above.

No luck with the above, can help you check the loop itself. Easiest/fastest to do that these days via email. Can get my address via the link in my sig below under "contact".

[5150Watts]

Message sent

[SDM]

Resolved via replacement. Hope you enjoy the loop Mark.

[5150Watts]

Loop is working great. Very very very slight tone difference when engaged but you really have to listen for it (cable probably the reason anyway.) Quiet operation and sounds fantastic. Doesn't overload my effects like my old loop did. Thank you Steve and George!