Help! Pedal causes buzz/hum

[Punch]

Hello,
I have a v847 usa revision b, which I have modded to true-bypass along with an led indicator according to this diagram:
http://www.fulltone.com/v847.html

The diagram is without a led, so my wiring includes a 3pdt and a led.

The Issue:
The pedal increases the level of hum/buzz (the same noise created by using an overdrive pedal).
The pedal adds noise even in bypass mode. This problem existed before I did the mod as well.
I turned up the volume on the amp, and having the wah pedal in the chain bypassed increased the noise by 10 decibels. My overdrive does not add noise like this.

What I've tried to do is:
Touched all ground connections, and metal parts, looking for a grounding problem.
Running it from a battery (I use a 1 spot)
Replaced both input and output jacks (with new, switchcraft ones)
Replaced the pot (it was scratchy but still)
Disconnecting all other pedals from the fx loop

The difference with my wiring is the following:
3pdt switch, led anode connected to center lug of the new row.
led cathode connected to 330 ohm resistor, connected to the output jacks sleeve.
An extra wire from the battery clips positive to the 3pdt, so the led can light up.


Can you guys think of any possible solution to removing this extra added buzz? The pedal works fine otherwise and the led is great, but I need to get rid of the added noise.

[jasperoosthoek]

Could you supply some more information: What the pedal is supposed to sound like (is it a wah???). Did you build it yourself? Can you supply a schematic (not just a wiring diagram). Do you have pictures of what you built?

Even the most helpful people can be a bit lazy .

[thedefog]

From the sound of it, it seems like you may have a grounding issue. Can you take a picture of the inside?

-Sorry, I just realized you said it was doing this buzzing sound prior to the mod, so ignore the part I wrote about the true-bypass wiring. 

[Punch]

Yes, it is a wah, a Vox v847 USA made, revision B. There is no problem with the sound of the pedal, or the led, the only issue is the added noise. I did not build it myself, I did however modify it and need help resolving this issue. I don't believe I caused this issue though.

I will take a picture of the inside when I get a chance. I'll also make an exact diagram of how I have it wired up now.

Thanks

[MikeH]

Did it have the hum issue before you modded it?

[Punch]

Hello again,
Here is a diagram of the exact wiring:
http://img176.imageshack.us/i/v847newmod.gif/

Here are gut shots of the inside of the pedal, though it's quite messy I'm not sure if it will help.
http://img155.imageshack.us/i/img1087l.jpg/
http://img801.imageshack.us/i/img1089h.jpg/
http://img543.imageshack.us/i/img1090z.jpg/

Also realize I don't really know anything about pedal electronics, I just followed the diagram. I found a diagram for a led, saying the 3pdt needed a "+ from the battery", so I just added a cable to the "+" from the battery. It works with the led, but could this be the source of the problem? I tried adding 2 resistors (330 ohm each), and I believe it seemed to take off some of the buzz according to my decibelmeter, but I'm not really sure. Does that seem possible?

I read somewhere about dc bleed or something, maybe that is the problem?

[MikeH]

If I'm looking at it right, the battery connection in that diagram looks wrong; the battery is connected to the same place as the output tip.  That would cause hum for sure, and it would also dump DC out into your signal chain, which is bad for your amp if it's next in line.

Just for starters, anyhow.

Edit: Ok, I see it now, the switch is rotated 90 degrees.

[Punch]

So the wiring looks OK?

Does it even make sense to add a resistor to the red + battery cable? I'm just guessing stuff here...

[jasperoosthoek]

One thing looks a bit weird. You should connect the ground side of the LED directly to the battery not to the jack socket. Now the LED current which is about 19mA runs from the positive battery lug to the switch, through the LED and resistor into the output socket, through the enclosure to the other socket, through purple wire to the PCB and back to the battery. Power supply noise will be imposed as a voltage on signal lines. Even if this doesn't solve the issue it's a thing to look at first.

A much smaller LED current will still be almost as visible. I use a 2.2k resistor which limits the LED current to about 3mA. 19mA will drain your battery very fast (in about 30 hours). The current of the wah itself will be negligible compared to the LED. But if normally use a power supply you shouldn't worry about that and keep the 330 ohms resistor.

[askwho69]

you need regulated power supply! or the http://www.beavisaudio.com/projects/Huminator/index.htm this may solve the problem.. for hum

[deadastronaut]

your jacks look very close to the enclosure...especially when you put a jack in there...

turn em ...

[Punch]

I still have the issue.
Here is the diagram of the current wiring:
http://img689.imageshack.us/img689/1671/v847newmod.gif

I have:
Replaced pot
Replaced jacks
Installed 3pdt

The wah function works, the led lights up as it should and the bypass function works.
The pedal adds noise wheter it is on or off. The noise is there wheter I am using a power supply (1-spot) or a battery. No other pedals make this noise.

Something else I've noticed. If the wah is plugged in, and I unplug the cable from the input jack, I get a loud buzz similar to having a guitar cable in an amp but not connected to a guitar. This buzz is also decreased when I touch any metal in the surface, such as the amps knobs or the cables from the pedals.


Please look over this, the diagram and tell me anything that might be of help. I feel it must be a wiring issue, since all parts except the main pcb are new.

[askwho69]

AHA THE PROBLEM IS GROUND~!!

[Punch]

Okay, so if there is a grounding issue, how do I find it?

Perhaps the wiring with the grounding is wrong, could you guys look at the diagram and perhaps tell?

[jasperoosthoek]

Check the connections to the input/output jack. It sounds like one of them is reversed and as a result the enclosure is directly connected to a signal wire instead the ground. Can you also test that with a DMM/resistance meter?

[Punch]

The jacks are wired like the diagram.

I tried to wire it like this now:
http://img101.imageshack.us/img101/939/3pdtwiring.jpg

I added the ground (red wire) because it removed a loud buzz sound. However, with this wiring, there is no guitar signal. The led works, and I can hear the wah sweep sound when engaged, but the input cable does not have any sound, even if I unplug it from the guitar and touch it. This did however seem to minimize buzz.

Is there any way to make the guitar signal come through with the above wiring?
Thanks

[askwho69]

youre so wrong doing that my friend.. you put ground to the hot one? try connecting ground of the input and output of the jack..

[Punch]

Haha, that is quite humorous, connecting the ground to the lead made it quiet because it killed the signal! 

I disconnected the ground from the lead, and while trying the pedal it does now not appear to add noise with only it plugged in. Perhaps this was the correct diagram, I am not however 100%, have to do a more thorough examination tomorrow.

This only leaves one thing, the ground which comes from the output jack and is connected to the pot is now hanging free. (The only reason that loose ground didn't add noise now was because of my touch). Where should I connect it? You are suggesting the sleeve on the input correct?

Thanks

[askwho69]

Ground of input and ground of output try connect them!

Cheers
A2

[Punch]

Wow, now I can't find any issues with it. I've put the cover back on for the first time in ages, and it works now 
The sound is now free from buzz and interference and the LED is shining nice and bright!

There do not seem to be any issues for now
Thanks