Slo Nakid FX Loop Installed...but getting squealing

dinkyguitar

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So I think I messed up with the placement of my FX loop...right over V1 & V2...I now know it's not the "best" place.

FX Loop.jpg


Powered it on and if I have the overdrive an higher than 3, it squeals....high pitched.

I unscrewed the mounting screws on the board an placed the loop on top of the chassis and the squealing goes away.

At this point I'm not sure what the fix would be, other than removing it.....but I would like to have a FX loop if possible.



dinky
 
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Snfoilhat

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Is there room between the pins of the tube sockets and the bottom of the effects loop daughter board to install a metal shield anchored to the chassis? Something about the same size and shape as the board?

Ive seen some old equipment packed tightly and the designers used metal fins to shield one side of a transformer, or even a steel box to enclose a 1/4” jack on three sides
 

dinkyguitar

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I think I might have solved my issue.

The 68k grid resistor to V1....I took a piece of sheet metal, wrapped it in blue tape and covered that resistor and the high pitch squeal went away...removed the sheet metal, and it came back.

I guess that grid resistor is very sensitive....

I could re-route that wire to run along the bottom chassis plus use a shield of some sort that covers the bottom of the FX loop.

Also, I don't have a schematic of the loop....but it's this board. On the pic it's on the upper left.

FX LOOP.jpg
 

dinkyguitar

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Is there room between the pins of the tube sockets and the bottom of the effects loop daughter board to install a metal shield anchored to the chassis? Something about the same size and shape as the board?

Ive seen some old equipment packed tightly and the designers used metal fins to shield one side of a transformer, or even a steel box to enclose a 1/4” jack on three sides
you hit the nail on head..

I just posted my above reply after seeing yours...
 

dinkyguitar

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I believe I fixed the issue 👍

I was able to turn the gain all the way up and no noise.

Seemed like a quick fix....I just ran the wire to the grid resistor under the board, and since 1/2 of V1 is not used, lay the resistor between the unused pins to where it connects to.

FX Noise Fixed.jpg


Tomorrow I'll have more time to really test her.
 




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