POP when pluging into normal channel

[HBamps]

I just picked up a silverface DR and am pretty psyched about it. One thing I cant figure out is I am getting a fairly loud POP when plugging (or unplugging) into either jack of the normal channel. Once plugged in, it works and sounds fine.

When I had the chassis out, I cleaned the jacks and scrapped the contact between the 'hot' tab and the springed ground tab.

Any ideas what it could be??

Thanks for looking!

[52 Bill]

Pops like that are sometimes caused by leaky grid on a preamp tube or could be caused by a conductive fiber board. Some source of voltage at the input jacks that is being discharged by the plug.

Try switching the first two preamp tubes and see if the problem moves to the vibrato channel.

[HBamps]

I have done a bunch of tube swapping, not for this reason, and haven't noticed it go away. I will specifically try this though.

I suppose I should also check the shield on the input grid cable, and the 1M to ground at the jack for that matter.

thanks for the response!

[52 Bill]

Try reading the dc voltage on the input jacks. Plug in a cord and read across the other end plug. Anything there?

[HBamps]

Try reading the dc voltage on the input jacks. Plug in a cord and read across the other end plug. Anything there?

Another great idea. I'll try this tonight.