I just got a Mutron Octave Divider that won't divide. I've been measuring and probing and can't nail down the problem yet.
Here's the schematic; http://homepage.mac.com/sonicvi/mutronoctave.pdf
Here's what i know.
The pedal passes signal all the time even with the mix knob all the way to the bass side, and the tone control and ringer switch both work. Essentially everything works as it should except there's no divided tone.
There's power to both circuit boards.
With the audio probe I get signal on the logic board between P4-9 and the input of the 4013 and from the P4-10 up to Q2 (2n5457). So signal it seems is entering and leaving the logic section board but not being divided. I get a loud distorted signal before the 4013 which is what I expect, but get nothing out of the 4013. I already tried a new 4013 and a new 4011 to no avail.
I discovered by accident with my finger that if TP8 (or pin 8/9 of the 4011) is connected to pin 1 of Z4 (4558) that the divided tone will come back. So I think the problem is somewhere in this general area, but I can't figure it out yet.
Any ideas of what else to check?
That's a pretty old PCB. How confident are you that all the pins of the various CMOS chips are making good contact with the sockets? It only takes one bad pin contact to screw things up.
I thought of that so I reflowed all the solder connections of the socket for the 4011 and the 4013 was not socketed so I removed it and added a socket and a new chip. Maybe I should try a whole new socket for the 4011, but I got continuity between ythe socket pins and the pcb pads so that seemed unlikely. i also don't see any sign of broken traces.
Okay, well at least we can rule that out.
If I jumper TP8 to pin 1 of Z4(A) then the divider works, which means the 4013 must be doing its job. Jumpering those two points essentially bypasses the area around the Stabilize switch, Q4 and Z4B. So I suppose I should investigate that area more closely. It would help if I understood how the stabilze circuit actually works!
Fixed. Z4 was bad.
Next problem, none of the LED's are working.