Aion Tonebender mk 2 high pitched squeal

[suryabeep]

Hi everyone,
I built an Aion Tonebender mk 2, but there's a high pitched squeal when I crank the fuzz knob. The Voltages are (EBC):
Q1: 0V, -0.13V, -9.4V
Q2: 0V, -0.093V, -0.34V
Q3: -0.23V, -0.33v, -8.6V
I saw on http://www.diystompboxes.com/smfforum/index.php?topic=100137.0 that soldering a 100R resistor between the pcb and Fuzz3 can remedy the issue, but how do I do this using PC mount pots?

[Electric Warrior]

Have you tried putting a bigger capacitor between -9V and ground yet?

Is Q2's trimmer maxed out? Looks like you could use bigger resistances at Q1b and Q2c, though they can sound nice in the range in which it's biased now.

[suryabeep]

I don't have 50 uf, so I'm guessing 47 uf is close enough right? I'm happy with the tones I'm getting right now, but just that dang squeal is annoying me. I'll report back once I've changed out that power filter

[thermionix]

In capacitor world, 47=50.  You can measure a bag of 47s and many will read over 50.

Have you tried moving wires around?  Lead dress can be important in high gain situations.  Did you build on a PCB?  Come up with your own layout?  It's even possible that two components are closer together on the board than they want to be.

[suryabeep]

Have you tried putting a bigger capacitor between -9V and ground yet?

Is Q2's trimmer maxed out? Looks like you could use bigger resistances at Q1b and Q2c, though they can sound nice in the range in which it's biased now.

SUCCESS! I tried the 47uf cap on c8 and there's no squeal now. Sounds great, really nails the led zep tone. Thank you!
On a side note, why does a bigger cap reduce the squeal? Just curious