Fuzz Face problem...

[HeaD]

Hi, I have built this circuit following this scheme: http://www.generalguitargadgets.com/diagrams/fuzzface_sc_pn.gif, and this layout http://www.generalguitargadgets.com/diagrams/fuzzface_lo_pn_3pdt.gif. It's a FF with negative grond. I know the problems of this wiring method, but I would like to try to make it work because I would like to be able to use it without a separated power supply by other pedals, and for any other reasons.
So... the Bypass works correctly, but when active the pedal strangely does not work at all (even if the LED lights up). The caps polarity is correct and the other components seems to be right. I have used two germanium AC128, with Hfe respectively of 70 and about 80 for Q1 and Q2.
Here are the voltages of transistors and other points of the circuit. I use a 9v alkaline battery not new (8,12 V)but I do not think that the problem is due to this...:

Q1:
E = 8.09V
B = 7,98V
C = 7.42V

Q2:
E = 7.56V
B = 7.42V
C = 5.02V

And looking herehttp://img117.echo.cx/img117/7348/fuzzfacescpn1mb.gif:
P1 = 7.55V
P2 = 0.27V

I have tried to do a test with audio probe, after the P1 point there is a signal loss and after C3 the signal is almost nonexistent.
What can be the problem? Thanks!  

[HeaD]

No one can help me?  

[dosmun]

Is there a decent signal before C3?  If so try replacing C3.

[HeaD]

Is there a decent signal before C3?

there are 0.27V.... and the signal is a little low

[petemoore]

Q1:
E = 8.09V
B = 7,98V
C = 7.42V

Q2:
E = 7.56V
B = 7.42V
C = 5.02V
 These voltages are not in the operational range for biases.
 Q1 emitter should be connected to ground.

[HeaD]

 Q1 emitter should be connected to ground.

...not in negative ground configuration.

[HeaD]

Other ideas? :/

[petemoore]

What's wrong with establishing you have Gnd at Q1E?

[HeaD]

What's wrong with establishing you have Gnd at Q1E?

Ok, i try...

[HeaD]

I have tried with  Q1 E to ground. unfortunately the problem persists....

[petemoore]

If you socketted, pull the tranny and hook a ground wire to it.
 Well first see if you have Gnd. at Q1E, the voltage there would be Gnd or 0V...but you could check anyway with the DMM from Gnd to Q1E in beep mode.

[HeaD]

If you socketted, pull the tranny and hook a ground wire to it.
 Well first see if you have Gnd. at Q1E, the voltage there would be Gnd or 0V...but you could check anyway with the DMM from Gnd to Q1E in beep mode.

Yes now the voltage at Q1E is 0V... but it still not work... are u sure of this?

[petemoore]

Well I don't know what "This' refers to

[HeaD]

Well I don't know what "This' refers to

I've seen several schemes of Fuzz Face negative ground ... and I've never seen Q1E to ground. For example this http://www.muzique.com/lab/fuzzface.htm.

I'm only a beginner, and if you say me that there is a possibility of making it work connecting Q1E to ground, I do it. But it still not work.  :?

[petemoore]

The 1k, the ~22uf, the Volume pot, and Q1 emitter all are going to ground on the link directly above this post.
 The only FF type I know of uses a slight resistance from Q1E to Gnd. : The YAFF  at AMZ.
 There must be another problem.
 Neg Gnd PNP FF's are notorious for problems without solution.

[HeaD]

The 1k, the ~22uf, the Volume pot, and Q1 emitter all are going to ground on the link directly above this post.

I was referring to the second scheme of the Link.... the negative ground. In the negative ground Q1E is not to ground. ok?

Neg Gnd PNP FF's are notorious for problems without solution.

As I already said I know negative Ground problems... and I think that this my problem not regard negative ground wiring.


So, anyone can help me with the real problem of this circuit?  :?

[Karmasound]

I wasn't going to post in this thread becuase it is like leading a horse to water but he won't drink..


There can only be a few things that are wrong.

1. It's wired wrong.

2. one of your parts is bad

3. the transistors don't want to be run neg. ground

it's up to you to make the choices



just doesn't make sense that if you know the problems with neg. ground that you would refuse to think that that is the problem.

[petemoore]

I see two schematics on that AMZ page: 'Positive ground for the FF".
 I see Q1 Emitter connected to ground on both schematics.

[HeaD]

I see two schematics on that AMZ page: 'Positive ground for the FF".
 I see Q1 Emitter connected to ground on both schematics.

"Positive power supply"... maybe is not positive ground...

[HeaD]

3. the transistors don't want to be run neg. ground

I have read of problems of oscillation or noises, but I've never thought that the transistors couldn't want to be run negative ground...