Fuzz Face Humming Problem

Ofek Deitch · June 14, 2013, 04:21:06 PM

Hi guys,

I recently built two Fuzz Faces with BC109s in them. The problem is that one of them hums really bad, though the other doesn't hum at all.

Has anyone had this problem before? Is it possible that the problem is caused by the transistors, and because of that only one of the two pedals is humming?
Both are powered with the same power source.

*Working on front and back pictures of the PCB..*

Thanks !
Ofek

rousejeremy · June 14, 2013, 04:41:23 PM

Bad ground.

Ofek Deitch · June 15, 2013, 02:48:04 AM

By Bad ground do you mean that something that shouldn't be grounded is grounded? or vise versa - something that should be grounded isn't?
Is there an easy way to find out where the bad ground connection is, or do I have to go all over the PCB and also check all ground connections with my MM?

rousejeremy · June 15, 2013, 10:44:38 AM

follow the ground traces on your board and scrutinize every connection.
Do you have any good pics of the bottom of both PCB's to compare? Also the connections to the jacks and power etc.

Thecomedian · June 15, 2013, 10:53:08 AM

could you describe how the sound is and how it changes with turning volume knob? Or post pics of them side by side?

R.G. · June 15, 2013, 12:08:27 PM

Something should be grounded but isn't.

The easy way to find the bad ground connection *is* to go over the whole board and check all ground connections. Other halfway measures will probably take longer overall.

Ofek Deitch · June 15, 2013, 02:15:53 PM

The problem is that I only have this super blurry picture (below) because I sold this pedal to a guy, and it's the only gut shot I've got.

I'm pretty sure it worked when I sent it to him, but now he says he hears a humming sound so I told him to send it back to me and I'll try to fix it for him.
So here's what I've got for you guys to examine, while the pedal is on its way back to its loving home:

New pix in a week or so (hopefully)..
Thanks for your help!

Ofek.

induction · June 15, 2013, 03:22:00 PM

Was your friend using an adapter or a battery?

Ofek Deitch · June 15, 2013, 03:34:35 PM

Quote from: induction on June 15, 2013, 03:22:00 PM
Was your friend using an adapter or a battery?

I donno, but he said he powered both pedals with the same power supply, and only one did this buzzing sound, so it probably isn't a power source issue..

Ofek Deitch · June 26, 2013, 01:27:01 PM

The pedal is back!
After playing a bit with it I noticed that it hisses - (not humming). The problem is that I have no clue what causes that hissing..

Could it be caused by the transistors?

A few pics of the pedal:

This is the layout I'm using:

Thanks for any help!
Ofek

Hemmel · June 26, 2013, 01:48:05 PM

Quote from: Ofek Deitch on June 26, 2013, 01:27:01 PM

Looking at this pic, and name columns with letters and rows with numbers :

There seems to be a small strand that shorts from J4 to K5 to L7. Is that just a hair ?

Ofek Deitch · June 26, 2013, 02:53:51 PM

I'm not sure what it is, though it isn't causing the hissing.
I also found out the the hissing almost disappears when I turn down the volume knob (Master Volume on the pedal) and when it's up the hissing gets louder. Plus, the pedal is humming while the Fuzz knob is turned all the way up.

I've tried this thing (Below:) and it stopped both the hiss and the sound.

I also tried to put a bigger filtering cap between +9v and Ground but it had no affect on the hissing.

GGBB · June 26, 2013, 03:05:40 PM

I've read RG post this on more than one occasion regarding EMI/RFI filtering for high-gain pedals - add a 10-100n ceramic cap between 9V and ground. Maybe that will eliminate the hiss.

Paul Marossy · June 26, 2013, 03:27:39 PM

Quote from: Ofek Deitch on June 26, 2013, 02:53:51 PM
Plus, the pedal is humming while the Fuzz knob is turned all the way up.

Are using a guitar with single coil pickups?

Ofek Deitch · June 26, 2013, 03:37:16 PM

add a 10-100n ceramic cap between 9V and ground.
Didn't work

Are using a guitar with single coil pickups?
Yeah - strat with single coils.
why?

GGBB · June 26, 2013, 04:04:01 PM

Does the pre-gain control change the hiss in any way?

Ofek Deitch · June 26, 2013, 04:11:17 PM

Yeah, when the volume on the guitar is all the way down, and the pre-gain is all the way up the hiss disappears, but as I turn the pre-gain CCW the hiss comes back and gets louder.

Paul Marossy · June 26, 2013, 04:14:51 PM

Quote from: Ofek Deitch on June 26, 2013, 03:37:16 PM
Are using a guitar with single coil pickups?
Yeah - strat with single coils.
why?

A high gain circuit will take any small amount of hum from single coil pickups and amplify it. Doesn't sound like you have anything abnormal going on there. If it also did it with humbuckers then I would say it's maybe something to do with the circuit, grounding, etc.

Ofek Deitch · June 26, 2013, 04:26:38 PM

But what's weird is that I have two of these FFs and only one hums..

Paul Marossy · June 26, 2013, 04:30:24 PM

Quote from: Ofek Deitch on June 26, 2013, 04:26:38 PM
But what's weird is that I have two of these FFs and only one hums..

Maybe that one has more gain? Do they sound the same otherwise?

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Fuzz Face Humming Problem