Weird problem with Univox superfuzz clone

[Atodovax]

Hello everyone. Im experimenting a weird problem with my Univox Superfuzz clone. With the pedal plugged in, with the expander pot at minimun and the balance at maximum, i still get a weak signal passing through the output. Is this normal? it seems there should not be any signal if the expander is at 0. Same thing the other way. If i put the balance at minumum and expander at max, i have a fainted signal at the output... Do you have any clues?

[MikeA]

Using the stock schematic, there's a 3.3k resistor between the Expander pot lug 1 and ground, so you'll always get a little signal thru that pot (lug 3 in to lug 2 out) even when it's fully counterclockwise (when it's a voltage divider with 50k pot in series and 3.3k to ground.) 

On the Balance pot, lug 1 is ground, so theoretically you shouldn't have a signal out of lug 2 when it's fully CCW.  However, the pot is probably greater than zero ohms between lugs 1 (ground) and 2 (out) when fully CCW, which may account for what you're hearing (voltage divider again.)  Or you may have coupling somewhere else in the build, like the foot switch or in/out leads.

[Atodovax]

Using the stock schematic, there's a 3.3k resistor between the Expander pot lug 1 and ground, so you'll always get a little signal thru that pot (lug 3 in to lug 2 out) even when it's fully counterclockwise (when it's a voltage divider with 50k pot in series and 3.3k to ground.) 

On the Balance pot, lug 1 is ground, so theoretically you shouldn't have a signal out of lug 2 when it's fully CCW.  However, the pot is probably greater than zero ohms between lugs 1 (ground) and 2 (out) when fully CCW, which may account for what you're hearing (voltage divider again.)  Or you may have coupling somewhere else in the build, like the foot switch or in/out leads.

Hi, thanks for the reply! Expander's leg 3 is conected to ground (im not using any resistor there to limit the minimun) so in pretty sure there shouldn't be any signal bleed there right? There has to be coupling somewhere but im getting crazy trying to figure it out. I checked both pots and both go fully to ground. Y even tried grounding the capacitor before the expander pot with an aligator clip and there is still signal at the output even with the capacitor grounded. Actually , if i ground the capacitors leg at the emiter's side of Q2, the output is muted. If i ground the other side of the capacitor (the one facing the pot) then there is some bleed through...

[MikeA]

Can you post the schematic and some pictures?

[Atodovax]

Can you post the schematic and some pictures?

Im using the stock schematic of the superfuzz with no limiting resistor at leg 3 of the expander pot. Apart from that, everything is stock as per the GGG Superfuzz schematic

[iainpunk]

seems like a capacitive crosstalk issue, where wires or components work as tiny capacitors and 'leak' signal into other lines or components. this or its a case of imperfect grounding, where there is still a resistance between circuit ground and actual ground so that ground conducts a tiny bit of the signal.

cheers