Fuzz Face Problem (fuzz knob doesn't work)

RonaldB · September 12, 2007, 07:30:40 AM

I made a fuzz face with this layout:

And i changed the the 18K resistor for a 10 trim pot and added a DTPT switch to switch between 470ohm or 1k.

Can someone please help me on this one

GREEN FUZ · September 12, 2007, 07:38:45 AM

A bit more information would help. In what respect does the knob not work?

RonaldB · September 12, 2007, 07:46:38 AM

I doesn't change the fuzz at all. I have a nice fuzz.
But i doesn't change when i turn the knob.

petemoore · September 12, 2007, 08:21:18 AM

Use the DMM to find where your build differs from what is shown on the schematic, oversimplified debug info, but basically that's it.
Read the debugging thread, you probably already have...
I'd start with the DMM probes probing around the gain pot...mostly setting it for R testing and in beep mode to verify continuities, N/C's and resistances.
Maybe the bypass cap has bypassed the gain pot entirely?

Dragonfly · September 12, 2007, 11:28:35 AM

Check your grounds

check to make sure that the pot is working (DMM to make sure values are changing when you rotate pot)

check to make sure the bypass cap is hooked up properly

King Tubby · September 12, 2007, 01:24:38 PM

What's with the cap on the fuzz control? is the schem/layout meant to say 22uf instead of 2uf?

GREEN FUZ · September 12, 2007, 05:19:14 PM

The red bracketed values are the Roger Mayer mods. I guess it is meant to be 2uf as the difference between 20 and 22 is going to be negligible.

King Tubby · September 12, 2007, 10:02:29 PM

I know there would be no difference soundwise. I was thinking more about availabilty, 22uf would be more common so that's what was used, like some schems ask for a 5uf cap with 4.7uf suggested.... oh I dont know...i'm still looking for a 2uf cap

RonaldB · September 13, 2007, 04:37:19 AM

Thanks guys for all the tips,

GREEN FUZ · September 13, 2007, 05:24:03 AM

Quote from: King Tubby on September 12, 2007, 10:02:29 PM
...i'm still looking for a 2uf cap

Well you can get `em alright, but why so expensive?

http://cgi.ebay.co.uk/CDE-Super-Pup-2uF-200V-Capacitors-x-5-Pieces_W0QQitemZ200150402170QQihZ010QQcategoryZ4662QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Of course two 1uf`s wired in parallel will do the trick also.

Dragonfly · September 13, 2007, 07:21:42 AM

Quote from: King Tubby on September 12, 2007, 10:02:29 PM
i'm still looking for a 2uf cap

You can use a 2.2uf cap, which can be found pretty much everywhere.

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Fuzz Face Problem (fuzz knob doesn't work)