Fuzz Factory Debug Help

[hall1k]

Hello, I'm working on my first build, a Fuzz Factory clone. All my parts are from Small Bear, and I've followed the schematic exactly and a layout that my uncle, who is an electrical engineer and a VP of Spectra Energy (natural gas company), produced for me, so i trust that it's correct. The only substitution I've made was using the OC76 Ge transistors in place of the AC128s, which were from Small Bear also.  I'm having some trouble though. As well, I am not using a battery, just a DC adapter, and no LED either. I am using the Taiwan Blue 3PDT from Small Bear.

For now, I'm just trying to get the true bypass working, but all I can get is a very loud buzzing (sounds like mains hum) with or without the guitar connected. When switched on, the pedal does nothing at all, not even any buzzing. Once I can get the true bypass working, I'll worry about the board itself, so at that point I'll go through the whole measuring voltages thing.

I have the true bypass hooked up according to this guide:

http://gaussmarkov.net/wordpress/thoughts/wiring-up-a-1590b/

[therecordingart]

Hello, I'm working on my first build, a Fuzz Factory clone. All my parts are from Small Bear, and I've followed the schematic exactly and a layout that my uncle, who is an electrical engineer and a VP of Spectra Energy (natural gas company), produced for me, so i trust that it's correct. The only substitution I've made was using the OC76 Ge transistors in place of the AC128s, which were from Small Bear also.  I'm having some trouble though. As well, I am not using a battery, just a DC adapter, and no LED either. I am using the Taiwan Blue 3PDT from Small Bear.

For now, I'm just trying to get the true bypass working, but all I can get is a very loud buzzing (sounds like mains hum) with or without the guitar connected. When switched on, the pedal does nothing at all, not even any buzzing. Once I can get the true bypass working, I'll worry about the board itself, so at that point I'll go through the whole measuring voltages thing.

I have the true bypass hooked up according to this guide:

http://gaussmarkov.net/wordpress/thoughts/wiring-up-a-1590b/

So with the switch bypassed it doesn't pass your guitar signal and with it engaged you get a loud buzzing? Can you take a picture of the guts and your switch wiring?

[hall1k]

Actually, I get the buzzing with the switch bypassed, but it does not pass the signal. With the switch engaged I get nothing at all. Unfortunately, I don't have access to a camera. I will draw a little diagram in paint and upload it tho. The jacks are grounded to the negative on the DC jack. I have tested that I have the correct polarity on the dc jack.

edit: here it is

[therecordingart]

That's right. I'd double check that the connections to the jacks are going to the tip and not the ring or sleeve. Also make sure that the tabs on the jacks aren't grounding to the enclosure.

[hall1k]

Its not in an enclosure atm. Its just sitting on a desk like a big jumble of wires... I connected the two jacks directly together to make sure they worked, and they worked fine. I'm really puzzled cause the bypass still doesn't work... I when the switch is off, there is indeed a small resistance across the bypass wire, though that could just be the wire itself... I'm really at my wits end here lol.

[ppatchmods]

how do you have you grounds run from the board?

[hall1k]

They go to the negative on the DC jack. Oddly enough, I just tried the bypass again and it works... /shrug

Now for the board lol... Is it weird for a resistor to show a voltage on one end and zero volts on the other? it does not look blackened or anything, so I don't think I burnt it.

[ppatchmods]

usually means it's bad

[tiges_ tendres]

They go to the negative on the DC jack. Oddly enough, I just tried the bypass again and it works... /shrug

Now for the board lol... Is it weird for a resistor to show a voltage on one end and zero volts on the other? it does not look blackened or anything, so I don't think I burnt it.

No that's not bad.  It might mean that one end of the resistor is grounded.

[NKLArg]

Hello everyone !

I built my first Fuzz Factory using the madbean 's PDF .

http://www.madbeanpedals.com/projects/Zombii/docs/Zombii_ver.5.pdf

And I am having a problem . I have a lot of gain. A LOT. Too much gain is my problem.

All wiring proper as indicated on madbean's PDF .
All components and potentiometers well placed and well wired
True Bypass wiring and running well - no led - a simple DPDT, (we can't get the 3PDT on Argentina anymore)
For Q1 I am using a 2N3904 (cannot remember his hFE)


My problem is probably in the transistors that I used for Q2 and Q3
In my country ( Argentina ) imports were closed . And it 's making us very difficult to get parts . Such as AC128 .
I could get two germanium transistors to replace the originals.

For Q2 2SB405 got a Sanyo (hFE 115) ( http://english.electronica-pt.com/components-cross-reference?ref=2SB405 )

For Q3 I got a Toshiba 2SB56 (hFE 185) ( http://english.electronica-pt.com/components-cross-reference?ref=2SB56 )



In the PDF of madbeans is suggested to (Q2 an HFE 70 ) and (Q3 an HFE of 110 )

I already tried many combinations up and down the values ​​of the resistors.
Also rising or decreasing values ​​of the potentiometers , Drive , Comp and Gate

nothing helped to lower the high gain buzz . No matter what the eternal beep does not go away .

Can someone please guide me on how to make the bias of the two transistors to lowering their gain or how I have to do to get rid of the whistle?

Please I need your help.
It took only an hour to do it, and i spendt four hours trying and testing to make it work well and I can not do it.
I don't want this one to end up in a drawer until I get the AC128, and that's probably never.

Anyone have any idea on correct way for biassing?

Thanks to all!

[LucifersTrip]

They go to the negative on the DC jack. Oddly enough, I just tried the bypass again and it works... /shrug

Now for the board lol... Is it weird for a resistor to show a voltage on one end and zero volts on the other? it does not look blackened or anything, so I don't think I burnt it.

When I've had bad resistors, they were "open"....even though they're in circuit and won't measure their true value, you can still measure them
to see if they're dead.

Regarding you're build, you're really troubleshooting/testing in reverse. The first thing to do after you have the circuit completed is usually to
test it WITHOUT a switch (effect "on"). There's no reason to add another factor when testing. (Ie, let's say you test the circuit now and it doesn't work, are you 100% sure it's still not the switch wiring?)

[LucifersTrip]

And I am having a problem . I have a lot of gain. A LOT. Too much gain is my problem.

welcome...

This is another job for the debug thread:
http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

There's not much use for us to take guesses until you know that your transistor voltages are close to what
they should be.

There should be nothing wrong with the Japanese transistors you got, unless the leakage is really high
(did you measure them?).  If not high leakage, there's no reason for AC128's.

1st step, check voltages and compare to voltages from working units (check the forum or maybe someone
will have some handy and help you out)

[NKLArg]

And I am having a problem . I have a lot of gain. A LOT. Too much gain is my problem.

welcome...

This is another job for the debug thread:
http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

There's not much use for us to take guesses until you know that your transistor voltages are close to what
they should be.

There should be nothing wrong with the Japanese transistors you got, unless the leakage is really high
(did you measure them?).  If not high leakage, there's no reason for AC128's.

1st step, check voltages and compare to voltages from working units (check the forum or maybe someone
will have some handy and help you out)

Wow! Thanks for the quick response!

I just have measured the voltages:

Q2 (2SB405) :

E: 8.89v (it's comes directly from the STAb Knoob - and STAB i'ts "killed" so i cant get the right voltages)
B: 8.81v
C: 7.54v

Q3 (2SB56) :

E: 7.75v
B: 7.54v (The same as the Collector on Q2)
C: 7.77v

Something is wrong, isn't ?

Thanks

[NKLArg]

Here are some photos:

http://imgur.com/a/RKPd4#0

[NKLArg]

Solve it!!! 

I put a 2k resistence in front of the Emitter of Q2.
And a 500 Ohm resistence in front of the Emitter on Q3.

This seems to "stabilize" the Buzzing. And now the Zombii works as it should be.

Don't ask me why 

I don't know how but it works

Hope someone find this helpful

Cheers!