MicroMoog doubler not working?

[kdawg]

Hi - I have a micromoog that I just got, but the doubler knob isn't doing anything - in center position I get the pure tone, fully CW or CCW I just get less volume but no octave or anything.

Schematic: http://www.fantasyjackpalance.com/fj...oog_main_2.gif

If you look at the "Doubler" area, I can see clock going into Q406 on the scope. I tried replacing Q406, CR403, and checked the resistors around. There is some clock getting out of Q406 but I don't know what it should look like. I'm suspecting IC404 (CD4013) is bad, but I have to order one... nothing good seems to be coming out of pins 1/8.

Any one have experience with this? This is the first Moog I've been in. Thanks

-kdawg

[Mars Amp Repair]

d latch

Q406 basically looks like a form of a buffer/limiter. If my digital memory serves, Ic404 is a D Flip-flop. It's like a JK flip-flop but with an extra clocking input..the D. Yeah I could look it up, too...it really doesn't matter at this point.
Since the not-Q output is connected to the D input I'm guessing that's partly how this flip-flop doubles the frequency...
Anyway regardless of my questionable memory, it looks like they have given you a graphic of what the input to the flip-flop should look like. It's a negative going pulse.
Regardless, all the pulses on all the leads of the flip flop IC404 should be some form of a square wave that is at least 5v p-p.
The base of Q406 would be a much smaller signal...about 1.4vp-p owing to the limitation of the diode junction of the transistor & diode CR403 creating a 1.4v 'window' for the square wave. I'm guessing that limits any amplitude aberrations...or something like that.

On the other side of R427 if you trace it back they say should be about 5vp-p at -13vdc.

Do you have 15V on the collector of Q406? If not then the input of the FF could be shorted & you're right it is probably bad. You could determine that by unsoldering that input of the FF. BTW though, you're dealing with a Mosfet device, so floating inputs are susceptible to static damage...

I'm sure someone will correct whatever errors I've made from the foggy memories of discrete digital circuits we used to fix back in the original VCR days! glen