The preamp in my '97C is inop. I've been able to verify the pickup works and that there is some continuity to the output jack and power to the output circuit. There's a problem somewhere between the jack for the pickup and the last stage of electronics before the output jack. I can plug the power into the board and get a thump out to the amp, but there's no audio from the pickup. Running the pickup direct to the amp does work. I tried another pickup plugged in but no joy there either (yes that pickup is verified good).
The touch-control volume circuit would be my first guess. I don't have the right kind of equipment to really troubleshoot this, like an oscilloscope. I've jiggled all the connectors and wiring with no luck.
Has anybody pulled out the touch control circuit board and messed with it or found simple fixes?
The last owner said it worked the last time he tried it. Since I've had it, nada.
Posted 2018-11-16 5:36 PM (#545856 - in reply to #545833) Subject: Re: '97C preamp failed
Joined: June 2012 Posts: 2317
Location: Pueblo West, CO
This may or may not help.
I've got an OP-Pro on my bench that I'm going to attempt to fix. Visual inspection of the circuit board revealed a couple of cold solder joints that need to be fixed.
So, you might try looking at the circuit board for any broken/cold solder joints.
Posted 2018-11-16 5:53 PM (#545857 - in reply to #545833) Subject: Re: '97C preamp failed
Joined: August 2011 Posts: 887
Location: Always beautiful canyon country of Utah
Tongue testing not necessarily indicative of available voltage. Voltmeter much better. Particularly because these units are sometimes fussy as to what voltage they will accept and still function appropriately!
'97C preamp failed