Silicon Fuzz Face Debugging

[Quadrapus]

I built a silicon fuzz face, it's my first pedal, there is no sound from the guitar and all i get is a buzz similar to when the ground between the jacks isn't connected (it's a bit quieter). The buzzing stops when i turn the volume pot all the way down, but otherwise happens whether the battery is connected or not. I rebuilt the whole board but still the same problem.
This is the layout I used: http://www.sabrotone.com/wp-content/uploads/2011/10/FuzzFaceSilicon.gif
I haven't changed the circuit.

Voltage at the circuit board end of the red battery lead = 8
Voltage at the circuit board end of the black battery lead = 0

R2
8
3.6

R3
0.3
3.6

R4
0.4
0.4

C1
+=0.4
-=0

C2
+=0
-=0

C3
8
0

C6
+=8
-=0


Q1
C =3.6
B =3.6
E =7.8

Q2
C=0
B=0.4
E=3.6

D3
+=0
-=8

VR1 (from top)
8
8
7.8

Any help is appreciated.

[dwmorrin]

Looks like your transistor pinouts don't match the layout.
Q1 should be:
Row E= emitter
Row F= base
Row G= collector

Q2 should be:
Row F= collector
Row G= base
Row H= emitter

Twist those legs around and see if that fixes it.

[MaxPower]

The schematic it's based on apparently:
http://www.generalguitargadgets.com/pdf/ggg_ff5_sc_npn.pdf?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a

Pretty much the same schematic:
http://fuzzcentral.ssguitar.com/fuzzface.php

Anyway, something is wrong with the R4 voltage readings. The end of R4 that is connected to R2 should have the same readings (8-9V more or less). The end of R4 connected to VR1 should have similar voltage readings as well (similar to the VR1 reading, not necessarily to the R4/R2 value).

The leads of C1, R3, and the base of Q1 should have equal voltages since they are connected together.
The collector of Q2 shouldn't be 0V.
Assuming you set VR1 to 8.2k Ohms, both ends shouldn't be 8V (or close to 8V).
The connections of R2, the Q1 collector, and Q2 base should have the same voltage reading since they are connected to each other.

There may be more issues, I gave up. So now a question:
Did you take all voltage readings relative to ground?
If so, you probably have some bad solder connections, shorts, or component failures.

[Quadrapus]

I checked again, but they match the layout.

[Quadrapus]

Thanks max, I'll go back through and check.

[Quadrapus]

Oops ,I messed up a few readings. Here they are fixed up:

R2
8
3.6

R3
0.4
3.6

R4
8
8

C1
+=0.4
-=0

C2
+=0
-=0

C3
8
0

C6
+=8
-=0


Q1
E =0
B =0.4
C =3.6

Q2
C=8
B=3.6
E=3.6

D3
+=0
-=8

VR1 (from top)
8
8
7.8

[MaxPower]

Those readings look much better. I'm not sure what the exact values should be but they make sense. Except:

Something still looks off with the VR1 and the Q2 Collector voltage readings. Adjust the resistance setting on the pot to different resistances and see if the readings change on the Q2 collector and the VR1 pot.

I'll run a simulation in Tina-ti tomorrow and see what kind of voltage readings one should expect.

[Quadrapus]

Adjusting the resistance seems to do noting. I assuming I'm going to have to buy another pot.

[LucifersTrip]

Q2
B=3.6
E=3.6

these are shorted (ie, accidentally soldered together or touching)

[Quadrapus]

Q2
B=3.6
E=3.6

these are shorted (ie, accidentally soldered together or touching)

I've checked and scratched down between them with a knife. There isn't a connection but the voltages are still the same, could it be something else?

[smallbearelec]

Looking at the flat side of a TO-92 transistor package with the leads pointing down, left-to-right should be E B C. I don't usually use Vero, and this layout is supposed to be verified. Still, this does not look right to me. Anyone else confirm or correct me?

[Quadrapus]

Looking at the flat side of a TO-92 transistor package with the leads pointing down, left-to-right should be E B C. I don't usually use Vero, and this layout is supposed to be verified. Still, this does not look right to me. Anyone else confirm or correct me?

I did notice that. The shape on the diagram isn't the right way, but I have my transistors in correctly.

[Quadrapus]

Seeing as my 10K trimpot (VR1) isn't working, I'm going to the electronics store tomorrow, is there any way I can just get an 8k2 resistor and wire that up instead?

[smallbearelec]

Seeing as my 10K trimpot (VR1) isn't working, I'm going to the electronics store tomorrow, is there any way I can just get an 8k2 resistor and wire that up instead?

Before you spend money, learn how to use the resistance scale of your meter and figure out how to measure the changing resistance of the trimmer. Problems with builds like this are rarely due to bad components; they are almost always the result of errors in wiring. What type transistors did you use?

[nocentelli]

Looking at the flat side of a TO-92 transistor package with the leads pointing down, left-to-right should be E B C. I don't usually use Vero, and this layout is supposed to be verified. Still, this does not look right to me. Anyone else confirm or correct me?

I did notice that. The shape on the diagram isn't the right way, but I have my transistors in correctly.

The layout has a note about consulting the internet for transistors - it perhaps is not specific enough about pinout, and marking C,B and E on the layout would perhaps help people brand new to the fuzzface, transistors and schematics. It would work as drawn for BC549, for example and plenty of others, but not 2N508x, 2N3904 and many other common Si npn.

[dwmorrin]

Quadrapus,
What transistors are you using?
Reading the same voltage at Q2 base and emitter is wrong.  It needs approx. 0.6V difference between the two terminals.
Did you connect the fuzz pot to ground?

[Quadrapus]

Quadrapus,
What transistors are you using?
Reading the same voltage at Q2 base and emitter is wrong.  It needs approx. 0.6V difference between the two terminals.
Did you connect the fuzz pot to ground?

BC108's, I also have BC109's

Yes, fuzz 1 (ground) is connected, and fuzz 1 is connected to vol 1.

[dwmorrin]

How about a resistance reading from Q2 base to emitter?
Pictures?

[Quadrapus]

I've now set the VR1 resistance to exactly 8.2 with my new digital multimeter.

How about a resistance reading from Q2 base to emitter?
Pictures?

72 on the 200k scale

[Quadrapus]

Okay, so I've figured it out. I read the vero layout as if i were looking through the board. I think I'll go live in hole fore the rest of my life

EDIT: Still doesn't work, new voltages next page.