DEBUGGING SI NPN FUZZ FACE

[deadastronaut]

WOLFY:  
i just breadboarded this with random 2n3904's and its fine...i put a 10k trim pot in place of the 8.2k to bias/trim it...try it, i'm sure it'll work ok....

the 10k pot will give great trumpeting fuzz too...an added bonus

i was messing around with input caps too, i like 10n/22n/ and tried a whopping 470n for full fatness..sounds better than the 2.2uf imo....

i'll post my video of it in a mo...

[deadastronaut]

vid..

[wolfy]

I still can't get q2 c down from 8.5 volts. I've got it right but somehow wrong somewhere! Will keep tinkering.

[deadastronaut]

try this, take your 330 ohms from 9v  into a 10k pot lug 3...lug 2 out to your Q2'S C....and adjust....

[nocentelli]

Are you definitely measuring it directly from the connector - virtually any npn silicon should be down closer to 4+half volts with an 8k2 resistor... Iunless it's faulty?

[wolfy]

I only have a 50 k pot on hand I'll give it a go in place of the 330r and 8k2.

I'm pretty sure I'm measuring it right. DMM - 20 volt range - black on ground and red on q2c

[GGBB]

I only have a 50 k pot on hand I'll give it a go in place of the 330r and 8k2.

I'm pretty sure I'm measuring it right. DMM - 20 volt range - black on ground and red on q2c

Leave the 330 - just replace the 8k2 with the pot.

[wolfy]

I've tried this with a 50k pot and it brings me down to 8.1v from 8.5 odd v. I know this isn't running smoothly for one reason or another. It has had to of happened to someone else!

[deadastronaut]

something definately wrong there.......double check the values of your resistors, and orientaion of trannies...and swap/change  trannies ....

if you follow the breadboard example above it will work....i guarantee it.....

[wolfy]

Starting to feel real bitter about it. I have built one successfully before months ago.
I have checked everything over and over again.
One more clue - The 50k pot i used in place of 8.2k (lug 3 to 330r, lug 2 to q2c, lug 1 unconnected) got the voltage down if I connected lug 1 to ground. I could get any voltage from 0 - 9v. When I plugged it into the amp and guitar it only worked when amp was cranked and fuzz pot didn't have any effect. Same old story.

I'm going mad over it - so many hours.

[wolfy]

Right - I found this FF calc made by Joe Davidson - http://www.diystompboxes.com/analogalchemy/emh/emh.html

Will report back after I reset resistor values to match my transistors hfes. *crosses fingers*

[wolfy]

No dice! Same thing is happening again at q2 collector. Voltage is about .5v off full supply voltage. ahhhh.

[GGBB]

I am feeling your pain and really want to see you fix this, so I have been staring at the pics you posted for a while now trying to see something (if only they were clearer).  Here's what I suspect - if in the pics we are looking down on the transistors from the bottom/pin side (the pins are sticking up), then assuming they are standard TO-92 2N3904s, you have them connected in reverse.  Swap the outside pins (C and E) on both.

[wolfy]

tried swapping trannies around but to no avail - i had them right the first time.

[wolfy]

In my frustration I built an Electra Distortion for the first time and it worked! Only took a half an hour to make. That made me happy.

[Renegadrian]

electra is good...strange you didn't get the FF to work properly...

[wolfy]

Too strange for me man. The electra worked first go so that made me happy.
The 3rd different effects circuit I've built. Only new in the game but I can tell you I've had to learn a lot to debug that fuzz face. I've had one going in the past - that's what kills me.

[wolfy]

Tommorow I'm gonna implement the electra mods and put it in a box!
I need some Ge transistors. Haven't played with them yet. Not sure if there are any in the 70s lowrey magic genie I have decided to use for parts. Plenty of old resistors, faders, buttons. Maybe some useful transformers for amp projects.

[Renegadrian]

...or try electradrian...

[wolfy]

That's the one mate - I'm going to do that tomorrow.