Man O War (Maxon AD900) build, help with clock noise?

[half_smith]

Hey all, I built this Man O War, you may have seen other posts I've made on here for help as I was debugging it.
1 bad IC, four broken traces, and hours of "biasing" (by ear, I don't have a scope), I got it functioning in a way I can use.

but the clock noise is pretty heavy as soon as I roll the DELAY time past a certain point.
I know I can adjust the trimpots in a way to avoid this ever happening, but that would defeat the point of a 2x mn3005 circuit.
I assume there is an underlying issue

Any idea what would be causing a less than great performance from my 2x mn3005s? Bad clock IC?

here's a video with demos
https://www.youtube.com/watch?v=FMFPdrQVWLs

[blackhatboojum]

From what I heard on your video, it doesn't sound like you have all of your trimmers adjusted properly.  Mainly the T1 and Level trim pots.  This circuit doesn't do the self oscillation / runaway feedback thing well, nor is it supposed to.  It gets pretty wonky and out of control if you have these set too high.  I just built this pedal about a month ago and didn't have too much trouble dialing it in.  I have to confess that I used a oscilloscope for visual reference but, in all honesty, Brian's instructions in the build docs are more than adequate.  That being said, how closely did you follow the instructions in the build doc?  Did you use an audio probe while setting the trim pots?  Does your multimeter have a frequency counter setting?  It's not needed but, it could help get your clock frequency just perfect if your anal about that type of stuff like I am lol.

[half_smith]

Thanks for your reply blackhatboojum
I have a Hz setting on my DMM, never used it before. I'll try that and see if I can dial it in better.

what is your longest delay time (before the distortion gets too heavy)?

[blackhatboojum]

Thanks for your reply blackhatboojum
I have a Hz setting on my DMM, never used it before. I'll try that and see if I can dial it in better.

what is your longest delay time (before the distortion gets too heavy)?

Set your delay knob to max and your mix and feedback knobs to minimum.  Probe pin 2 on one of your 3101s with your multimeter on its frequency setting.  Adjust the clock trimmer to around 7.5kHz.  The build docs show a value of 7.6kHz but, I was actually able to get mine down to 6.82kHz without clock noise.  Your mileage may vary but, 7.5kHz ought to give plenty of delay time without clock whine.  Do you have an audio probe?  This website https://www.szynalski.com/tone-generator/ and an audio probe is what I used to set the bias on both of my delay chips.  I can walk you through the way I did it if you want.

[LaceSensor]

Seems like your delay pot is wired backwards for a start
At least, my real Maxon AD999 doesnt work that way (appreciate its not an AD900...)

Other than that it seems like the delay time at max is too short, so I would be thinking about clock capacitor, one of the delay chips not working properly etc

[half_smith]

Thanks for your replies Blackhat, LaceSensor!
I have audio probed this board extensively, and I discovered I required 4 repaired/jumpered traces - not sure if I caused damage or it was a faulty board, but I had a hell of a time getting this thing to work at all.
I will try the Hz measurement that may help.
And something like a clock capacitor seems like a good deeper thing to look at. Would that be C20 / C25?
Is there a good way to test the 3101 chips? How to test the MN3005s?

[LaceSensor]

The clock chip is working cos you are getting delay
The MN3005 depending what it is might be a fake or a relabelled MN3008 (half the delay time)
Only way to test is a known good a working MN300X circuit