Good old fuzz faces..Help me finish them please!

[MrTonesNZ]

Hello! I started my first builds early this year, I made myself two amazing sounding FF's, one germanium and one silion. But i never got around to ironing out the creases and pakaging them properly. I had this weird issue where it sounded great when chained up with another pedal, but crap on its own. I tried many variations with different groundings and what not, but couldn't quite work it out. Anyway I've bought myself a DMM, and i'm dusting off those old circiuts, time to get them finised!

I wan't to see what went wrong. Where do I start with my DMM?

[LucifersTrip]

Hello! I started my first builds early this year, I made myself two amazing sounding FF's, one germanium and one silion. But i never got around to ironing out the creases and pakaging them properly. I had this weird issue where it sounded great when chained up with another pedal, but crap on its own. I tried many variations with different groundings and what not, but couldn't quite work it out. Anyway I've bought myself a DMM, and i'm dusting off those old circiuts, time to get them finised!

I wan't to see what went wrong. Where do I start with my DMM?

with the voltage readings of the transistors' lugs

[MrTonesNZ]

Hello! I started my first builds early this year, I made myself two amazing sounding FF's, one germanium and one silion. But i never got around to ironing out the creases and pakaging them properly. I had this weird issue where it sounded great when chained up with another pedal, but crap on its own. I tried many variations with different groundings and what not, but couldn't quite work it out. Anyway I've bought myself a DMM, and i'm dusting off those old circiuts, time to get them finised!

I wan't to see what went wrong. Where do I start with my DMM?

with the voltage readings of the transistors' lugs

Okey doke. My DMM has a transistor tester bit, should i use that?

[Derringer]

Hello! I started my first builds early this year, I made myself two amazing sounding FF's, one germanium and one silion. But i never got around to ironing out the creases and pakaging them properly. I had this weird issue where it sounded great when chained up with another pedal, but crap on its own. I tried many variations with different groundings and what not, but couldn't quite work it out. Anyway I've bought myself a DMM, and i'm dusting off those old circiuts, time to get them finised!

I wan't to see what went wrong. Where do I start with my DMM?

with the voltage readings of the transistors' lugs

Okey doke. My DMM has a transistor tester bit, should i use that?

I wouldn't worry about that ... just report back what the voltages of the transistor lugs are
like this

Q1
c:
b:
e:

Q2
c:
b:
e:

[MrTonesNZ]

I wan't to see what went wrong. Where do I start with my DMM?
[/quote]

with the voltage readings of the transistors' lugs
[/quote]
Okey doke. My DMM has a transistor tester bit, should i use that?
[/quote]

I wouldn't worry about that ... just report back what the voltages of the transistor lugs are
like this

Q1
c:
b:
e:

Q2
c:
b:
e:


[/quote]

Cool, should i disconnect them first?

[Govmnt_Lacky]

Cool, should i disconnect them first?

No.

Use your DMM and measure the voltages at the transistors with the pedal powered up and engaged. Connect the black probe to ground and the red probe should go to each leg of the transistors. Measuring DC voltage of course 

Make sure you look up the datasheet for the transistors you used. This way you will know which leg is the Emitter, Collector, and Base.

Good Luck 

[MrTonesNZ]

Cool, should i disconnect them first?

No.

Use your DMM and measure the voltages at the transistors with the pedal powered up and engaged. Connect the black probe to ground and the red probe should go to each leg of the transistors. Measuring DC voltage of course  

Make sure you look up the datasheet for the transistors you used. This way you will know which leg is the Emitter, Collector, and Base.

Good Luck  

Ok, would this be different for a positive ground one?

[boogietone]

Yes. Reverse the probes. General convention is the red probe is positive and the black probe is negative.

[MrTonesNZ]

OK, encountered problem no 1. 9v batt measures at 3.5 lol. need a new battery 

[MrTonesNZ]

Ok, assuming Ive done this right. I'm getting:

Q1
C- 4.25
B- 3.9
E- 9.08

Q2
C- 4.1
B -3.9
E- 3.95

[MrTonesNZ]

This is NPN silicon by the way

[blooze_man]

The Emitter of Q1 should read 0 volts. In other words, it should be connected to ground. I would start looking there. Also, the voltages of Q1 collector and Q2 Base should be the same cause they're connected.

[blooze_man]

Maybe it would help if you could describe exactly what you did to measure the voltages. I messed up the first time I tried to use a DMM. A schematic or picture of your PCB would help alot, too.

[MrTonesNZ]

The Emitter of Q1 should read 0 volts. In other words, it should be connected to ground. I would start looking there. Also, the voltages of Q1 collector and Q2 Base should be the same cause they're connected.

Ok, but isn't the Q1 emitter the input? Why would you ground the input?

[MrTonesNZ]

The Emitter of Q1 should read 0 volts. In other words, it should be connected to ground. I would start looking there. Also, the voltages of Q1 collector and Q2 Base should be the same cause they're connected.

Ok, but isn't the Q1 emitter the input? Why would you ground the input?

Hang on, thats the base..

[MrTonesNZ]

Ahahahaha!

Had the power in backwards!

Ok new figures

Q1
C: 3.74
B: 0.62
E: 0.00

Q2
C: 3.9
B: 3.74
E: 3.9

[LucifersTrip]

Ahahahaha!


Q2
C: 3.9
B: 3.74
E: 3.9

possible wiring or measuring error:
http://www.geofex.com/fxdebug/bias_prob.htm

"For linear amplifying, the collector must be more positive than the base; the base must be more positive than the emitter by about 0.4 to 0.7V for silicon, and 0.0 to 0.3 for germanium; the emitter should be the most negative pin."

"For an NPN silicon transistor (these all are) to be working as a linear amplifier, it MUST have its base higher than its emitter by about one silicon diode drop, 0.5 to 0.7V, and the collector must be higher than either base or collector. "

Shoot for close to this (page 5):
http://www.google.com/url?sa=t&source=web&cd=1&ved=0CBUQFjAA&url=http%3A%2F%2Fwww.generalguitargadgets.com%2Fpdf%2Fggg_ff5_instruct.pdf&rct=j&q=silicon%20fuzz%20face%20voltages&ei=NRwtTvHdIorY0QGR_ajkDg&usg=AFQjCNFzLn9xgl1dDZ3mom0I7c0KuqBKRQ&cad=rja

[MrTonesNZ]

Well when i compare to general guitar gadgets, the collector of Q1, and therefore the base of Q2, is significantly higher. Am i right in thinking I should try replacing R1 with a trim pot?

[MrTonesNZ]

 
Ok just fried it. Back to square one..