Mutron Ocatave Divider help needed

[ohmelter]

Hello. I've acquired a Mutron Octave Divider, and I'm not sure if the output of the device is correct or not. The volume output is really weak and the ringer appears not to be working. I can hear octave generation, although it too is weak.
I have an original schematic with the test points marked...However I'm not sure what I should be looking for at these points. I've pulled and tested all transistors and dual op-amps. They all test OK. I even replaced the 4013..that didn't do anything. I don't have an extra 4011 logic device to swap out.
Any help would be much appreciated. I need to know where to start.

Thanks in advance.

[theehman]

Have you checked power supply voltages?

[ohmelter]

Yes. There's plus 12 volts, and -11.66 coming from TP1 and TP2. I've tested diodes in diode bridge and they check good. All IC's are getting power.

[theehman]

Yes. There's plus 12 volts, and -11.66 coming from TP1 and TP2. I've tested diodes in diode bridge and they check good. All IC's are getting power.

There's the +/-12V and there's also +/-5 for the logic.

[ohmelter]

OK, I have to double check the voltage going to the logic circuit. I should have +- 5 going to the 4011 and 4013...right?

[theehman]

OK, I have to double check the voltage going to the logic circuit. I should have +- 5 going to the 4011 and 4013...right?

Correct.

[ohmelter]

OK. I've got +-12 going to the logic section, not +-5. The schematic dated 1976 doesn't indicate voltages. However, the 1979 schematic indicates +-12 going to the logic section. What's right? Or wrong?

[theehman]

It's been a while since I've repaired one of these.  I have a copy of the '76 schematic.  Since it has it's own set of zener diodes on the logic supply, I'd say those are different voltages.
Could you send me a copy of the '79 schematic?  I'd like to see how it differs.

[ohmelter]

Here's a link to the complete manual.

http://homepage.mac.com/sonicvi/mutronoctave.pdf

[theehman]

Looks like all voltages are 12v according to the parts list.  At this point your best bet is start audio tracing.  I'd start at the Blend control and work my way back from there.

[ohmelter]

Found the problem. Bad electrolytic cap from the first gain stage to the Mix control. I replaced all electrolytics in circuit, just in case another decides to go. Probably time to do so anyway.