Hotrod Deville squealing?

[craigslee]

Hi guys,

I have an issue where I have a high pitched squealing occurring in the "more drive" channel as I increase the gain, treble or middle. (pretty much anywhere past half way)

I have found that, with the back panel off, the squeal will disappear completley when I place my finger on the ribbon cable of the second preamp valve.

The issue is not evident in the 2nd input. Just the 1st input. (higher gain?)

Can anyone explain why this is the case?

P.S. I have just replaced all my preamp valves with new JJ's. It still happens.

Thanks in advance.

[Enzo]

Tuck that ribbon more down towards the tube.

Over by the power tubes, there is a blue and brown wire from the OT to push-on connectors on the tube socket board. One of them - the blue I think - passes across the ribbon there. ROute that wire as close to a right angle to that ribbon as possible.

[craigslee]

Thanks Enzo. I'll give that a try.

[tonalvision]

problem

I had a hrdeville that had a problem with the more drive channel. It was not a squeal but that channel was underpowered and had a distorted fizzle. Local amp tech diagnosed it as a bad diode after conferring with his pals at Fender. Charged me $225.00 for a $1.00 diode. Oh well, I certainly wasn't going to find the problem on my own. I used to read Justin Holton"s Unofficial Hot Rod deluxe page, but it is gone now. Someone saved his work here. zSHARE - The Unofficial Fender Hot Rod Deluxe Owner_s Guide.zip Good luck and be safe!

[craigslee]

Thanks for the input tonalvision. Excellent Link to BTW.

The squealing actually related to my positioning of a post-overdrive tone circuit. EMF interference!.

All I had to do was move the little mod board further away from the preamp valves and input circuitry.

Now it sounds amazing. Best thing I ever did to my HRD.