Vox AC4TV scratchy noise from guitar controls

[vintagekiki]

To avoid doubts about DC on the input jack, temporarily connect TempC capacitor (10-22nF) between JS1 and R3 (10k).
Check R2 (1M) that its value has not "increased" to a higher value (> 5M), so the ionic current Ig1 occurs.



1) Check the ground connection (SG1) to the chassis.

[pdf64]

Interesting and makes sense for "normal" grid leak current. What's your source?.

Haha, I’m not certain but seem to recall Merlin mentioning it.
Also it’s a common issue with one of the Trainwreck models, which have a low voltage operating point on their input stage, so it’s a regular on the TAG sub forum.

[Helmholtz]

I’m not certain but seem to recall Merlin mentioning it.
Also it’s a common issue with one of the Trainwreck models, which have a low voltage operating point on their input stage, so it’s a regular on the TAG sub forum.

Thanks, found some reference here: http://www.valvewizard.co.uk/Triodes...s_Blencowe.pdf

TAG means The Amp Garage?

[g1]

TAG means The Amp Garage?

Yes. And sometimes you will see people refer to 'TGP' which is The Gear Page.