Fuzz Face debug help needed

[black mariah]

Grah. Okay, I'm building a standard Fuzz Face on a GGG Boutique Fuzz Face board. I'm doing PNP, NEGATIVE GROUND, and I'm lost as to how to bias this damn thing.

Q1 and Q2 have the same readings.
C: 8.86V
B: 8.86V
E: .56mV

HUH? As you may have guessed it's frickin' CRACKLY and blatty. I substituted jumpers for the pots on the BFF, and put the standard value FF resistors in place of the BFF values so it's a standard Fuzz Face... only PNP negative ground which I have no idea how the hell it works...

I should have stuck with the positive ground, eh?

[enigmur]

It doesnt seem right that they would have the same readings. Check your soldering and make sure everything is right. If you are using strip board check all trace cuts are correct.

Also check that the transistor pinout is corrent, some are BCE instead of CBE

[petemoore]

  Battery is *probably ok' I assume.
  Grah. Okay, I'm building a standard Fuzz Face on a GGG Boutique Fuzz Face board. I'm doing PNP, NEGATIVE GROUND, and I'm lost as to how to bias this damn thing.
  I would 'beep' test between all/any two points showing = voltage, it looks as though Q1 and Q2 are paralleled...daft 1 I dunno..
  To save long type and frustration..
  Give up on that and convert a Fuzz Face instead.
  That schematic continues to cause intractable' problems, especially for newb's...-gnd. is attractive.
  The sure fire fix is..don't use it.
  To hear what a FF sounds like, choose a FF schematic, use a battery, and build that.
  It is easy to convert your board to a FF circuit.
  Doesn't a MAX1044 convert supply voltage polarity? That'd be one way to get a PNP ff on a neg gnd supply rail...anyone try that on a FF?

[hellwood]

Grah. Okay, I'm building a standard Fuzz Face on a GGG Boutique Fuzz Face board. I'm doing PNP, NEGATIVE GROUND, and I'm lost as to how to bias this damn thing.
Q1 and Q2 have the same readings.
C: 8.86V
B: 8.86V
E: .56mV
HUH? As you may have guessed it's frickin' CRACKLY and blatty. I substituted jumpers for the pots on the BFF, and put the standard value FF resistors in place of the BFF values so it's a standard Fuzz Face... only PNP negative ground which I have no idea how the hell it works...

I should have stuck with the positive ground, eh?

you cant just go and jump pots unless you put a resistor in its place. that will affect bias.

[hellwood]

oh, and your 10k trimpot should be able to give you 4.5v at Q2's collector.

[MartyMart]

You're asking for trouble Michael, "sometimes" you'll get lucky with a PNP neg ground, I have
just one that 'works OK" but it's not great - whereas I have several PNP pos grounds that are FAB and
also a couple of Ge NPN neg grounds that are great too.
I'd scrap the idea and try one of the other two options .... !
If it's just for the 9v PSU compatabillity, don't sweat it, a good well setup FF will last a very long time
on a battery.
MM

[black mariah]

you cant just go and jump pots unless you put a resistor in its place. that will affect bias.

I'm aware of that. Maybe I worded it oddly, but I jumpered all the extraneous pot connections (including the trimpot) and changed all the resistor values to standard Fuzz Face values.

In other words, I have built a standard Fuzz Face on the Boutique Fuzz Face PCB.

The bias issue was solved when I realized I'd put the pots in the wrong place (the way I'm having to mount this stuff, it has me twisted around like crazy. I reversed them and it works fine, except that when I have the fuzz maxed out and the guitar volume down all the way I now have a continuous noise. If I turn the fuzz down the noise disappears.

Could the fact that the Ge transistors I'm using are ridiculously high gain have anything to do with this? IIRC, they're 120 and 170 (as supplied by Small Bear).

Oddly enough the first Ge FF I built went off without a problem... 

[petemoore]

I'm aware of that. Maybe I worded it oddly, but I jumpered all the extraneous pot connections (including the trimpot) and changed all the resistor values to standard Fuzz Face values.

In other words, I have built a standard Fuzz Face on the Boutique Fuzz Face PCB.

The bias issue was solved when I realized I'd put the pots in the wrong place (the way I'm having to mount this stuff, it has me twisted around like crazy. I reversed them and it works fine, except that when I have the fuzz maxed out and the guitar volume down all the way I now have a continuous noise. If I turn the fuzz down the noise disappears.
Could the fact that the Ge transistors I'm using are ridiculously high gain have anything to do with this? IIRC, they're 120 and 170 (as supplied by Small Bear).
  Possible, What is the value of the gain pot ?
 

[captntasty]

A quick question on how you took your voltage readings: did you have a jack inserted in the input (assuming you used power switch on the input jack)?  If not you will get readings like yours - you're basically reading the voltage of the battery almost anywhere on the board - I've made this mistake numerous times - doh! (smacks palm on forehead).  If this is why you are getting strange readings then the new readings should make more sense and help in biasing.
Peace
cap

[black mariah]

Possible, What is the value of the gain pot ?
 

1K, IIRC.

A quick question on how you took your voltage readings: did you have a jack inserted in the input (assuming you used power switch on the input jack)?  If not you will get readings like yours - you're basically reading the voltage of the battery almost anywhere on the board - I've made this mistake numerous times - doh! (smacks palm on forehead).  If this is why you are getting strange readings then the new readings should make more sense and help in biasing.
Peace
cap

I've done that before too. Yeah, I had a jack in the input.