Bugera 333xl effects loop switching

[gweedo]

Hello, just aquired a bugera 333xl head with a couple of issues, wondering if anyone could help. First problem : when switching effects loop on or off there is a loud pop thru the speakers , I am assuming this is a noisy relay as it does sound louder than other relays when switching and all cap's, resistors in circuit seem ok, the second issue is that it came with a footswitch that has a 5 pin DIN plug & the amp has a 5 pin mini DIN socket, without schematics its a bit hard to locate correct wires to change plug or socket,could someone help with a wiring diagram, thanks

[Enzo]

Plug a guitar cord from send to return FX loop pjacks. Does it still pop? Does it pop with NOTHING plugged into those jacks?

Does your existing FS work? if so, trace the wiring from the working unit.

It appears the mini-DIN is 5 pin, and the odd lower pin on the one side is ground. That leaves the other four wires as switched to ground most likely. The schematic doesn;t call out the function of each wire.