Marshall AVT150H channel switch popping

[rf7]

There's a loud pop that this amp makes when you switch from the OD channels to the clean channel. I've replaced the DG212 switching IC's that seem to pertain to this (IC2 & IC3), but it's still happening. It does not occur unless a guitar is plugged in to the input. Any ideas?

[pecorporation]

Do you see any failing solder connections on the input jack. Sometimes a loose ground pin can cause noise on switching.

If your model is an older version, you might check the attached mod for the switching circuit AVTservb1.pdf.

[rf7]

I tried the mod, did not make a difference. I replaced IC107 in the rear board, a cmos quad switch, still popping.