China AC128 Fuzzface Clone

[zequ]

Hello DIYers

i bought this pedal off alliexpress knowing it was probably fake and not going to work, figured it was a good learning experience. I'm a decent solderer.   Took about 15 minutes to assemble.

Want to keep it out of the landfill. Decent fuzz tone but signal is muddy and fuzzed when off. Board is G161122.PCB

Kind of like the fuzz tone it produces but would like to make it true bypass to have a clean tone when it's off.

Here's a link to the photos of the pedal and the board they sell. This is probably selling a lot because it's just 20$ for a DIY Fuzz face.


https://mega.nz/#F!8RBEUQjT!Yhp-eNfR065Z_5n5flkR-w

I wonder if someone might recognize this pedal circuit and know of how to make it true bypass?

Thank you all.

[Plexi]

Can you share the aliexpress link?

[zequ]

Yes here is the same package. Mine was from landtone,  but this has the exact same parts.

https://www.aliexpress.com/store/product/NEW-Fuzz-Face-pedal-kit-for-guitar-effects-pedal-with-1590B-silver-case-free-shipping/1045809_32738815630.html

I've found an excellent webpage full of fuzzy goodness that might just answer my own question.

http://fuzzcentral.ssguitar.com/faq.php

Thanks

[thermionix]

It should already be true bypass.

[zequ]

it sound very low and slightly fuzzed when in the off position and when i change the Gain pot, the signal is changed, all while the pedal is supposed to be off. another thing - when i lower the tone on my guitar to full  base (home made telecaster) when the fuzz is on, the fuzz goes into this weird overdrive. hard to describe, it starts clipping like crazy. interesting lofi distortion effect. all in all, the pedal has a narrow working window where it sounds like a decent fuzz but it's a very small window.

[tinkertech]

I bought several of these kits for a workshop I wanted to teach, and while I was doing the build, I was comparing the circuit on the PCB to a standard PNP Fuzz Face schematic and noticed a couple discrepancies:

1) The 2.2uF on the input appears to be backwards (+ end should face the input, not the transistor base)
2) The side of the volume pot (500k) that should be connected to ground appears to be connected to the -9V bus

I just started playing around with this about an hour ago, so I'll update you if I find that reversing that cap and cutting the trace to the pot and replacing it with a jumper wire to ground helps at all. I'm going out of town tomorrow for about a week, though, so it'll be a bit before I can come back to it.

[Marcos - Munky]

Well, that AC128s probably are conterfeit. It doesn't really matter if it sounds good to your ears.

Anyway, that 3PDT wiring looks wrong. Post a picture of the back side of the board, and I can draw you an correct one.

[mac]

I have some 2n2218 and 2n2219, motorola, that look exactly like those ac128.
Check the base emitter voltage to know if they are silicon or germ.

mac

[AJR]

Any progress on figuring this one out?

[pinkjimiphoton]

it sound very low and slightly fuzzed when in the off position and when i change the Gain pot, the signal is changed, all while the pedal is supposed to be off. another thing - when i lower the tone on my guitar to full  base (home made telecaster) when the fuzz is on, the fuzz goes into this weird overdrive. hard to describe, it starts clipping like crazy. interesting lofi distortion effect. all in all, the pedal has a narrow working window where it sounds like a decent fuzz but it's a very small window.

two things... first, its a positive ground circuit being run with a negative ground. you may need to use a humongous decoupling cap across the power rails... like, 2200uF or more.

second, sounds to me like ya may have the q's backwards from your description. try flipping them 180 degrees.

also, replace the 8.2k resistor with a 10k trimmer pot, may help dial in a bias that works.

these chinese germaniums need to be socketed. literally 2 seconds of heat from an iron can permanently destroy them, but they sound killer if not overdone

[GGBB]

Not that their picture is an actual picture of the AC128s they are shipping, nor that I am an expert, but that Motorola logo doesn't look quite right to me:

[pinkjimiphoton]

yeah, they ain't no motorolas

i bought 10 of them to check out. two dead completely. 3 that read as p channel jfets with a vgs of 65 VOLTS. 

the rest were decades apart, 30ish, 40oish, 50ish, 60ish and finally one that was reading about 67hfe. that one sounds great in a pnp fuzzface i chucked it in. surprisingly, all of the so-called good ones from 30 on up sounded pretty similar, and not bad. the ones that read as jfets sounded bloody horrible, all nasty and totally misbiased even with compensation from the trimmer i had on c. the two duds just sat there.

none of these ones have the motorola logo. but other than that, look identical, and all BRIGHT and SHINY,

my vote is they suck, but in reality i did get like, 4 or 5 out of 10 that were useful, which with germanium is actually fairly good.

the things will fuzz nicely, if ya can get a decent set. may be worth trying a si in place of one of the q's

[andrea2127]

hi, i've bought the same kit from aliexpress and it also happened to me. if the pedal is off the guitar's sound it's still a bit distorted. When i go home i post some pictures. the layout seems the same as mine, i think it's the same kit.

[pinkjimiphoton]

hi andrea,
welcome to the forum!

yeah, if its still distorted when off, there's an issue somewhere with the wiring.
landtone, protaitone, a whole bunch of them are all the same.

in bypass the only thing there should be from in to out is a piece of wire.

it doesn't help that its shipped with a 3pdt switch, and the board is for a dpdt

[resonet]

Hello, I am experiencing problems with this kit as well. So, if I understand correctly, the main reason why it does not work properly is that the 2.2uF on the input is backwards and the side of the volume pot (500k) that should be connected to ground not to -9V, correct? Does anybody make this fuzz working? Thank you, greetings from Slovakia.

[pinkjimiphoton]

Hello, I am experiencing problems with this kit as well. So, if I understand correctly, the main reason why it does not work properly is that the 2.2uF on the input is backwards and the side of the volume pot (500k) that should be connected to ground not to -9V, correct? Does anybody make this fuzz working? Thank you, greetings from Slovakia.

the input is right, the + side should face the higher voltage potential, and the 500k pot does indeed connect to -9v. kinda.

its a botched attempt at a pnp run on a negative ground is the problem.

pnp's, the red lead goes to your ring input, and red also goes to the center pin of your power jack. black goes to the + pin of your power jack.  that way ya cans till use the input to save your battery.

i had to put a 2200uF cap across the rails to make mine stop oscillating.

there's no schematic included, so ya gotta actually trace thru the dang circuit while looking at a schematic to see how it goes together.

i finally sorted it out last time,
here's the board, and how to wire it so it will work

but don't be surprised if the transistors are dead if ya soldered them. sucks.

[resonet]

Yes, thanks. I saw your artistic picture before but I have not tried to duplicate your circuit. But now it is the last try, if it would not work I throw this crap to trash immediately :-) Spent million hours for this junk, enough is enough...

[pinkjimiphoton]

it was the only way i could get it to work bro, but the transistors were lunched and i had to replace them both.

[jdom1984]

thats cool check out my posts to see my fuzz face modded Satans Anus!

;-)

But its silicon.

This looks cool would like a cheap way to try a Germanium version! :-)

[pinkjimiphoton]

too @#$%in lazy, brah... post a link instead. love the name