Diaz Square Face Fuzz/NPN Fuzz Face vero layout clarification?

[Bandwagonesque]

          Hi everyone. I drew an original Vero layout for a clone of my Diaz square face fuzz (basically an npn fuzz face). I wired it up and and so far its been plagued with it doing nothing but a barely there gasping raspy dull fart, not so much fuzz. I looked at the usual suspects including cap and transistor polarity and bridged traces/solder whiskers and the lot but couldn't source a thing. It powers on and bypasses fine. I double and triple checked my layout and wiring, then did so again and couldn't find a thing wrong in regards to it in relation to my original square face and even any other fuzz face schematic really. Its housed in an old 8mm film canister so I took that into account when checking my grounds and couldn't see anything missing. I am using nte123ap silicon transistors (the square face used these for the silicon option), and germanium 2n2222's. The 2n2222's sounded great in a tone bender I recently had debugged thanks to the folks here and figured they should work. The square face fuzz I had used nte103 germ transistors and have some on order now. But for now I'm cross referencing both sets of transistors. I replaced the 8.2K with a 20K trimpot (dont have any 10K's) to bias it but for some reason it still sounds the same whether its the 8.2K resistor or trimpot, and I can't dial in it at 4.5V on Q2's collector (and do tell me if I'm doing It wrong as I'm still rather green). The trim just stays at around 9.3X volts.

So in saying all that I can't really figure out what's wrong aside from replacing components now (have ordered some nte103's like the original to try just in case but I dunno). It feels like its a grounding issue but everything looks great. It's kind of frustrating as the circuit seems dead simple but is just not all there.

I am near certain there's no issue with my layout but then again I said the same about my last build problem and was glad to stand corrected by some good folks here. So I do hope there's something obvious that I am overlooking and somebody else may catch it. I'd be very much grateful for any help to hopefully get this thing working as it should.

Attached are my Vero layout and my voltages for Q1 and Q2 of the nte123ap's and 2n2222's I'm using.

Q1: 2n2222germ npn
       120ufe
C:    1.22
B:     0.60
E:     0.00

Q2: 2n2222germ npn
       140ufe
C:     9.36
B:     1.22
E:     0.77

Q1: NTE123AP silicon npn
       170ufe
C:  1.18
B:  0.59
E:  0.00

Q2: NTE123AP silicon npn
       150ufe
C:  9.38
B:  1.18
E:  0.77

[PRR]

> Q2: 2n2222germ npn
> C:     9.36
> Q2: NTE123AP silicon npn
> C:  9.38

Q2 C is stuck at battery voltage. Fuzz pot is NOT hooked up.

And FWIW, 2N2222 is Si not Ge.

[Bandwagonesque]

Hi PRR, thanks alot for your reply and for correcting me on that transistor. I wrongly assumed it was germanium due to its case but its most definitely silicon so thanks for pointing that out so i don't make that same mistake twice.


Do you happen to know why its stuck at 9V? is it the fuzz pot? I keep on looking back and forth between my layout and schematics and can't really see what you're seeing in the fuzz pot not being hooked up but would love to know whats amiss. forgive me for still overlooking what you're referring too.

[Slowpoke101]

NPN Fuzz Faces are going to drive me nuts.....

Remove power and also remove Q2. Now measure what resistance you have across the trimpot.
What do you get and can you vary it by adjusting the trimpot?

[PRR]

> why its stuck at 9V?

Because the 1k pot with the 0.77V on it tell Q2 to pass 0.77mA. Which should cause 6.3V of drop in the 8.2k resistor.

You have "no" drop in the 8.2k resistor, stays up near 9V. Therefore where you think you have a 1k (pot), you don't.

I can't see the problem from here. Wrong pot value? Bad joint? Joined to wrong place?

[Bandwagonesque]

hi folks, sorry for taking a bit before I could give an update. I embarrassingly discovered that my pots were wired with an incorrect value for the fuzz pot. the pots were the one thing i did not remember to check foolishly and that was what ended up being the problem. when i did get it working it was very noisey with everything on 10, so i had to get some miller caps put on the transistors. never knew what those were about so it was nice to run into that problem to learn something new. but all in all it works great now and sounds killer.

Thanks a bunch PRR. Without you're first reply I don't think I would've remembered that I had not checked the pots after all. Doing that got this thing working again so thanks again. and thanks for pointing out my transistor confusion. i must've thought they were germanium for being in a metal can package but they're indeed silicon.

[freshmex18]

What biases did you end up getting for each transistor?  Does it end up biasing the same as a standard FF or are the values different for the Diaz?