Princeton Chorus - No reverb

[Low Rider]

Hi, I'm new here so forgive my lack of knowledge . My red knob Princeton Chorus has no reverb. I should explain that I had a few damaged pots so I replaced all of them. Now evrything works fine except the reverb. The return side is working (can here springs when tapping the tank), and the tank is ok (plugged into another amp, worked fine). The cables checked out ok. The pot also seems to be working as level of spring I can here changes with adjustment. I don't have a signal generator to get the TP values, and I don't have a capacitor checker (other than a DVOM). I have been searching on here and found that the op-amp on the reverb drive side could be the cause of this issue. I assume from the schematic that U4a (TL072) is the op-amp in question and I have measured +16v &-16V at pins 8 & 4. Those are the only measurments I knew how to take. I don't know if it applies to this circuit, but I've read that probing pin 3 with a paperclip should cause a hum in the reverb. I do here a slight click when I do this, but no hum.

So, am I in the right ballpark? Is there anything else I can try? Any suggestions would be greatly appreciated.

[Jazz P Bass]

You can hook up a CD player to the input to help with troubleshooting.
The TL072 is a dual chip. The input pins are 2/5 & 3/6. The output is pin #1/7.
You can measure the output pin voltages with a DVM.
That will tell you if the IC is doing anything.
Fender typically has voltages marked on there schemes.

It would be helpful if you posted the schematic.

[Low Rider]

Princeton Chorus schematic

Thanks for the quick reply. By hooking up a cd player, do you mean to the reverb tank cable or the amp input? Here is the schematic.

Adam

[Low Rider]

Sorry, that attachment probably won't be readable. I couldn't upload a bigger file.

[Jazz P Bass]

Fender Princeton Chorus Schematic

Hook the cd player into the amp input.
Follow the little triangles on the schematic.
The triangle is the symbol for amplifier.
As in opamp.
Look at the output pins.
Pin #1 & #7.
Volts AC on your meter will read the signal.
You will see as you advance across the circuit, from the input jack towards the output, that the signal will (usually) steadily increase.
Look for where it drops out.