Reverb pot in a drip edge PR

[mrhudson27]

Hola, all.
I just came into a Princeton Reverb (‘68 per chassis code, date of 7/27/69 written inside chassis in red marker). Appears to be bone stock down to RCA tubes (haven’t tested them or verified that proper preamp tubes are in proper positions). One exception- the reverb pot housing differs from all other pots & has some type of set screw in the back? When I first tested it (after an initial slow power up with a lamp limiter) the reverb seemed to be at a static low rate up to about 5, then then extreme scratchiness ensued & reverb disappeared. Figured pots were all dirty, so I hit them all w/ contact cleaner. No scratchiness in any pots now, but reverb totally bye bye. Connections at pan & chassis verified solid & correct. V2 & V3 tubes glowing.

Am I looking at a funky pot that someone used to replace the original, and what’s w/ the screw in back? I’m thinking the pot is the culprit since it had SOME attainable reverb at first.

Thoughts?

[PRR]

The "screw" is so you can stack assorted units to make a multi-gang pot, if you need to; or to work a switch. This is a universal replacement part suitable for 30-day warranty radio/TV repair. I doubt Fender put it in there.

Get a bright light (and if you are older than this amp, a magnifier) and inspect the solders and the wafer. Maybe it just needs a touch-up. But don't spend a ton of time fixing a $1 pot where should be a $1.50 pot. Less-inappropriate new pots are readily available?

[HotBluePlates]

... Princeton Reverb ... I’m thinking the pot is the culprit since it had SOME attainable reverb at first. ...

The stock pot is 100kΩ Linear.  If you always felt that you had too much Reverb and need to keep that pot set low (like 2 or 3), consider using a 100kΩ Audio when you replace the pot.