Fender Princeton Chorus question

[BassThumper]

Hey all, I'm new to the site. I surfed across it while looking for information about a problem I'm having with my older Fender Princeton Chorus amp. A little background... I bought 1988 Fender PC from a friend back around 2000. It was used as my practice/backup amp for a couple years until a friend borrowed it and it fell out of his vehicle and sheared off the volume pot. So I took it to an electronics tech guy at my work. He replaced the pot with one of matching resistance. But... this caused a MASSIVE decrease in volume on the "clean" channel. The overdrive channel is still very loud however. So I gave the amp to a friend for a few years. I recently re-aquired it and figured that I wanted to get it fixed. I bought a new 500k pot from Radio Shack and installed it... still no luck. Same problem as before. So now I'm thinking that I will attempt to replace it with an actual OEM part. Problem is I can't seem to find the part number anywhere. I found a website with a ton of Fender OEM pots but I need to know the exact part number. So... if you're still with me after all of that, I'm asking a 2 part question. First, has anybody ever heard of a similar problem? Second, does anybody know where I can find the part number for the volume pot (500k) for the clean channel of a 1988 Fender Princeton Chorus amp? Thanks in advance !!

[52 Bill]

...So now I'm thinking that I will attempt to replace it with an actual OEM part. Problem is I can't seem to find the part number anywhere. I found a website with a ton of Fender OEM pots but I need to know the exact part number. So... if you're still with me after all of that, I'm asking a 2 part question. First, has anybody ever heard of a similar problem? Second, does anybody know where I can find the part number for the volume pot (500k) for the clean channel of a 1988 Fender Princeton Chorus amp? Thanks in advance !!

Hey welcome to the board.

According to the schematic that I have, the volume controls are both 50K linear taper pots. The Fender part number is 027941.

The wrong value may be the only problem with the amp, but there could be other issues like broken traces on the board, etc.

Is the volume really low or is it just low compared to the knob setting on the distortion channel?

[BassThumper]

Hi 52 Bill, thanks for the reply. I guess I hit one too many 0's. Yes, I meant to say I put in a 50k pot from Radio Shack. The new pot is a lot larger physically then the original Fender part so I didn't know if there was a special pot I should look for. In regards to volume, it's just a lot lower than the overdrive channel, much lower. Before the original pot sheared off the clean channel had a lot of volume and very comparable to the overdrive channel. I can now dime out the clean channel and get a volume roughly equivilent to the volume around "2" when it had the original part. Thank you for the part number ! I will order one and hopefully that will fix this great little amp.

[52 Bill]

I can now dime out the clean channel and get a volume roughly equivilent to the volume around "2" when it had the original part. Thank you for the part number ! I will order one and hopefully that will fix this great little amp.

My guess is there is another problem with the amp.

The clean channel signal drives the distortion channel, so the signal is being cut off at the volume control or the channel switch IC.

I'd check to see if there was any physical damage to the board when the pot was sheared off. Check the continuity of the traces from the control to the other parts of the circuit.

Also, the original pot had a metal mounting bracket that Fender sometimes used as part of the ground circuit. Make sure to jumper any important pc traces that the original metal bracket may have connected together.