Marshall AVT100 FX not adjusting

[Barrym]

Here is the AVT100 schematic.

[ATTACH]36845[/ATTACH]

Thanks, thats great, now its time to dig out the screwdriver and stuff

[gearhead63]

I have an Vallvestate 2000 that is popping/crackling, it doesnt seem to be the pots or switches, more likely a capacitor failed, Are switches also available as the OD1 switch is sticking on the preamp, the footswitch works ok, but can't switch when the OD1 preamp switch sticks.

Thanks for any help

Does it pop/crackle when you have headphones plugged in? If it's clean then the contacts on the headphone jack are dirty. Not making good contact when the headphones aren't plugged in.

[g1]

Does it pop/crackle when you have headphones plugged in? If it's clean then the contacts on the headphone jack are dirty. Not making good contact when the headphones aren't plugged in.

Which model are you referring to? The AVT100 does not have the headphones after the power amp.

[gearhead63]

My bad G1, was thinking of the 50.

[Lee Steel]

Hi Everyone,

I also have one of these amps, actually 2. I have an FX Loop that does not adjust to 100% wet when mix is rotated completely clockwise. There is also a noticeable "open ground" kind of sound (as if a cable is not plugged in) that gets louder as the knob is rotated. You can hear the inserted effect, but not completely.

Also, Footswitch will not control amp but the buttons on the amp are working to select channels. Any assistance would be very much appreciated.