Maestro Ring Modulator RM-1B troubleshooting help

[Gladmarr]

Hi all!  I haven't posted for a long time, but I could use some help troubleshooting a Maestro RM-1B Ring Modulator.

If you reference this schematic, I'm trying to figure out what the signal strength at pin 5 of ic2b should be.    I have like 150mV peak to peak at pin 5 and nothing at pin 7.  If anyone out there has one or a clone, could you please look under the hood and give me some idea what the peak-to-peak voltage out is at pins 5 and 7? 

Thanks much!

[Gladmarr]

I managed to fix this thing myself. It turns out the numbers I was asking for wouldn't have helped much afterall. There was some weirdness with the output amp's gain setting resistors being out of spec. The squelch circuit puts a DC offset on the ring mod signal as it approaches the final opamp. The opamp swamps out the signal when that DC offset (plus the gain of the opamp) runs up against the opamp's voltage rail. With the gain being out of whack, the squelch was happening as soon as you'd touch the string. I was able to adjust that back out and the output signal now sounds like a ring mod again.

[Paul Marossy]

I managed to fix this thing myself. It turns out the numbers I was asking for wouldn't have helped much afterall. There was some weirdness with the output amp's gain setting resistors being out of spec. The squelch circuit puts a DC offset on the ring mod signal as it approaches the final opamp. The opamp swamps out the signal when that DC offset (plus the gain of the opamp) runs up against the opamp's voltage rail. With the gain being out of whack, the squelch was happening as soon as you'd touch the string. I was able to adjust that back out and the output signal now sounds like a ring mod again.

Interesting, thanks for posting that for future reference. These ring modulators can certainly be tricky, finicky things to work on. But once they are working properly, lots of fun.