Uno Fuzz (PCB Guitar Mania)/Univox Super-Fuzz

[SprinkleSpraycan]

I cant get this thing to work and I think its the transistors. I wired the pcb to by test box and nothing! So i've been running a jumper from the out to different components to see where the signal stops. That usually helps troubleshoot but in this case im more confused. Seems to get to q3 (however its very faint) and then i dont really know. Instead of the listed 2sc828 I used 2N3904. Are they just not a good substitute? I hope someone has had experience building this. FYI the transistors and diodes are socketed for now in hopes to experiment with it...hoping to get to that point soon.






https://pcbguitarmania.com/wp-content/uploads/2020/12/Uno-Fuzz-1.1v-Building-Docs.pdf

[eh la bas ma]

First thing that comes in mind is your transistors pinout :




Looks like you'll need to bend a leg on each one, if they don't have the same pinout. They should work though, I see 2N3904 is 60-300 Hfe, 2SC828  is 130-500 Hfe, both are NPN, you might have a slightly lower gain but i am not sure.

There's also your socketed diodes.
Russian germanium diodes have the marking on the positive side. A simple diode test with your multimeter should clarify things about their polarity.

Your wiring. Make sure the ground network is correct, with  continuity tests. Mistakes are often made with the wiring.

A clear picture of the soldering side could help us spot some suspicious soldering joints.

I guess a certain well-known and distinguished member would surely and kindly say something like "rule n°1 still applies here : where are your voltage readings on these transistors ?"

[idy]

He spotted it: 3904 is EBC, 828 is ECB. That will do it!
The diodes don't worry about. Although it is true that Russians put the stripe on the "wrong" end, in this circuit its just a "anti-parallel" pair and it doesn't matter which one points "up" and which one points "down."

[pacealot]

I guess a certain well-known and distinguished member would surely and kindly say something like "rule n°1 still applies here : where are your voltage readings on these transistors ?"

Not somebody one would want to run a fowl of, surely? 

[SprinkleSpraycan]

Looks like you'll need to bend a leg on each one..

Totally worked. Thanks! I'll know to look for that next time. Is there a better transistor you suggest for this since I can't get the 2sc828?

Thanks again!!

[pacealot]

If the pinout is the main concern, there are some other BCE-pinout BJTs out there. There are a lot of other 2SC-prefix Japanese parts which share that same pinout (although they don't all, so make sure you check the datasheet), and also there are other parts such as the 2N3707 (a personal favourite) with the same pinout as well (and many old "top hat" TO98-packaged BJTs have the BCE pinout as well). But if you don't mind bending the legs, the 2N3904 is perfectly fine for a Super Fuzz-type.

That said, a number of people who've tried different trannies in this circuit (and I am one) prefer lower hFE's in it, so perhaps the 2N3903 would be a slightly better fit. My personal preference is anything with an hFE of under 180, and make sure to match Q4 and Q5 as closely as possible for the best octave-up effect. YMMV and all...

[eh la bas ma]

So far, my method would be :

go on musikding.de, enter "npn", wait for the suggestions to appear, then open every interesting results in differents windows/tabs, and compare the Hfe numbers with what you are looking for.

But that's because they're my usual suppliers.

I wonder if there is a better way to search transistors, sorted by Hfe values, types (npn/pnp), etc. ?

Edit : if you bend legs to fit sockets, I suggest to use a bit of plastic from a wire on the bended leg, so it won't short with the other legs.

[idy]

I would not worry about pinout, unless you are having a machine assemble larger numbers of them. Instead I would just try a few different gain ranges.


Ignore pinout unless it is an OCD thing where you are tossing and turning all night thinking about those twisted transistor leads. Or really looking forward to a magazine cover type photo-shoot.

Go wherever you buy, find which  npn small signal transistors they have (you don't need power Qs), check the hfe. Try a few of the lowest you find, try a few in the middle. They should be cheap! I see a smorgasbord between .02¢ and .56¢.

[duck_arse]

Looks like you'll need to bend a leg on each one..

Totally worked. Thanks! I'll know to look for that next time. Is there a better transistor you suggest for this since I can't get the 2sc828?

Thanks again!!

the BC182L, BC183L, BC184L are all npn and end-base pinout. make sure they are L suffix tho, and the gains might be too high for the hFE sniffers.

the BC series transistors come in four ranges. taking BC548 as our example, they can be one of BC548,  BC548A, BC548B or BC548C. no suffix can be anywhere between 100 and 700 hFE's, the A is the low end of the range, the C range is the high end, and the 548B is the most ordinary transistor you will ever need.

[SprinkleSpraycan]

Thanks all for the help! The superfuzz came out great. I matched 2n3903 for q1,2,3 & 6. Then matched 2n3904 for q 4 &5, it tamed the octave just a little to my ear and maybe boosted the gain a little too. I added a toggle to have germanium clipping and silicone (i used 1n4148). And a pot for the tone. Totally rips!