SOLVED: some help on fuzz face voltages... (boutique, pos. ground)

[barret77]

Hello all

I'm debugging the boutique fuzz face I've built;

It's vero, based on the pos ground boutique fuzz face from GGG:
http://www.generalguitargadgets.com/diagrams/fuzzface_b_sc_pp.gifhttp://www.generalguitargadgets.com/diagrams/fuzzface_b_sc_pp.gif

I've updated dragonsfly layout to positive ground, not 100% sure if it is all right:
http://www.metageometry.com/images/e_test.gifhttp://www.metageometry.com/images/e_test.gif

I've checked the traces, found nothing;
Adjusting the trimmer only makes the Q2 collector voltage up (to 9V...)

Battery: 9.14V

Q1:

C: - 1.5 V
B: - 0.87 V
E: 0 V

Q2:

C: - 8.3V
B: - 0.15
E: - 0.10

sound: there's fuzz, but it's not the good sounding... very very harsh

any ideas?
The trannys are ac125, tested and matched, from Pete Roberts...
I don't know what to do from here...

thanks a lot for any suggestion!

[mac]

Vc1 should be equal to Vb2 since they are direct coupled.
Also the values of Vc1 and Vb1 seems a little higher for an ac125.
Vc2 should be around 4.5 - 5.0V.
Looking at the schematic at ggg I'd say that the bias is the 1k pot and the contour the 50k input pot.

mac

[petemoore]

  hah...you're right, I missed the decimal point...new glasses
  But Q1Ccollector and Q2Base need to be connected.

[barret77]

nice, thanks for the feedback! I'll check it tonight!

[barret77]

Looking at the schematic at ggg I'd say that the bias is the 1k pot and the contour the 50k input pot.

hmmm... iare just the labels wrong? the schematic at geofex has similar pot positions, just small value differences...

[petemoore]

  the above "FFw/F.Mods" is a good schematic...

[mac]

about the labels, countour and bias, I mean that the pot at Q2 collector acts more like  bias than  countour, and the 50k pot at the input soften the distortion so it seems more like a countour to me... different points of view.
Anyway, the schematic is correct.

mac

[barret77]

Vc1 should be equal to Vb2 since they are direct coupled.
Also the values of Vc1 and Vb1 seems a little higher for an ac125.
Vc2 should be around 4.5 - 5.0V.
Looking at the schematic at ggg I'd say that the bias is the 1k pot and the contour the 50k input pot.

mac

ooops seems that they were connected, I was mistaken in the decimal point...

Dang, this is a simple circuit but I can't figure out why the voltages are soooo high! Already checked the traces, components a million times... tries other trannies and the voltage is around the same, way too high...

[petemoore]

Already checked the traces, components a million times... tries other trannies and the voltage is around the same, way too high...
  Measure them with the DMM where possible.
  Measure resistors, resistances of points that need continuity etc. [DMM Beep mode to check Actual Connections]...
  Maybe you put in a 470k where the 470 goes, I used to repeat that mistake.

[barret77]

Solved... drum roll

Ok, 2 small things:

1) shorted unused lugs on both pots that are used as var. resistors (I don't know if this makes a difference, but anyway...)
2) added a resistor to balance the trimpot: the 10k was going to 7k only... always check your components! even quality parts have lousy tolerances

and finally...

The AC125 pinout is the REVERSE of the AC128!!!!
Oh Lord!

I've spent all the time debugging the pedal - and it was working from day 1... I followed the pinout guide from geofex - http://www.geofex.com/FX_images/to1dwg.gif - and I never imagined that the TO-1 could have the flange in the collector instead of the emitter... Oh my!!!! I feel so dumb...

So, to whenever search for AC125 PINOUT and find this thread, write it down: flange is the collector. C,B,E.
I don't know if I have alien trannys, but mine are like that.

I'm going to write a build report on another thread, but it sounds very very sweet.

Thanks to PeteMoore and all other fellow members who helped me out...