Auto Wah Hum

[74BBeauty]

Hello, I recently bought an 80’s era Auto Wah (Aw-2) and a T Wah. Both do the thing that they’re supposed to do, but when I engage the pedal there’s a very noticeable hum. I also have a Dynamic Wah (AW-3) and it does not have the hum. I have other Boss pedals on my board all powered by a Voodoo Labs pedal power unit and my cables are good. I even tried using a battery for the two older pedals to remove them from the loop, but no luck. Any thoughts, or is this just par for the course with these specific models?

[Pepe]

Welcome! I remember the AW-2 being very noisy, but my model produced no humming sound. The TW-1 that I had was quite similar, a little bit noisy, but not distinctly humming.

What guitar pickups do you use? Do the wah pedals even hum with humbucker pickups or two single-coils at once? It could be that the digital AW-3 does have something like a noise gate inside that removes humming in the pauses. What happens if you completely turn down the guitar volume and activate one of these pedals?

[74BBeauty]

I’m using humbuckers mostly, and yes the hum is present no matter what. And when I kick in an overdrive pedal along with the auto wah or T Wah the hum is all you hear. Disappointing as I was really hoping one of those earlier models would work out. Oh well

[Pepe]

I suppose that there is some grounding issue. Could you open up the pedals and supply pictures* of the circuit boards (both sides)?

Strange, though, that both pedals are humming.

*The size for uploading single pictures on this board is limited to 400kb, so keep them relatively small iof you don't use an external source.)

[74BBeauty]

I’ve opened both pedals and they are clean, no oxidation or residue on the boards, and I cleaned the input and output jacks as well. I even moved the pedals around in different spots on the board to see if that made a difference. I think it just may be a bust on this one. And it’s unfortunate because had everything worked I would’ve chosen the TWah over the AW-2 and AW-3.

[Pepe]

So it is only the TW-1 producing the hum? I asked for pictures of the board because of possible cold solder joints. I have had dozens of pedals with issues and some of them simply had a few faulty solder spots. Maybe that's the case with your TW-1 as well.

[74BBeauty]

It’s both the AW-2 and the T Wah. Actually the AW-2 is worse. I will try to get photos posted soon

[The_Doc]

Just tested a stock AW-2 and TW-1 and both are very quiet through a Roland JC-40. No sign of any hum.

[74BBeauty]

Just my crap luck then

[Pepe]

In the case of old '80s pedals it can sometimes be completely sufficient if you put a bit new solder on every wire connection and on all the other components as well. Humming often results from some grounding issue and in most cases this is the result of improper connections. If I were you I'd try my luck with the soldering iron.