Rackwah has constant feedback, no guitar signal

[4nkam]

Hey everyone...So earlier this afternoon I went to go play some guitar and when I turned on my rackwah there was this annoying feedback coming through but NO guitar signal. The unit is an EMB Audio remote wah and it's controlled via a modified volume pedal. The pedal controls the voltage. The unit itself turns on fine, the "Effect" turns on fine, and the pedal works in the sense that it modifies the tone. Instead of the wah effect, it almost sounds like a whammy pedal.

I tried other expression pedals, XLR cables, guitar cables, guitars, etc. Everything...I isolated just the unit and an amp and yeah, it's the wah unit itself. The bypassed signal goes through just fine and it sounds normal, but once you turn on the wah effect it does the crazy whammy feedback noise.

I know it's gonna be pretty much impossible to get exact technical info regarding this unit, but electronically/theoretically, any idea what could be causing this?

[iaresee]

I've run the signal in reverse through my Morley to get weird screeching/controllable noise sounds before so I'm gonna ask the obvious: signal flow is correct right? Guitar -> input -> output -> amp? It's not accidentally wired up Guitar -> output -> input -> amp is it? Just asking...

[4nkam]

no worries,  I tried that too and it actually sounds the same.

[4nkam]

Here's a quick clip of what it sounds like: http://www.netmusicians.org/files/72-R09_0319.mp3

Keep in mind, the guitar signal itself doesn't go through when I turn the wah on. The sound you hear once it's on is constant and the guitar doesn't come through at all.

[4nkam]

Any ideas at all? I've checked my in/out, cables, components, etc...everything seems to be fine. MAybe it's a bad chip, bad power supply, etc I dunno.

[David]

Have you used an audio probe on it yet?