Need Electronics-type Help!

[lbpesq]

My pedalboard is putting out a high pitched tone, similar to the B string on my guitar.  It's not that loud unless I really turn up the volume, but it's there.  After troubleshooting I've narrowed it down to the aux out on my volume pedal that I use to feed a tuner.  If I unplug the jack at the aux out on the volume pedal, or unplug the power to the tuner, the tone goes away.   Thoughts?  Suggestions?


Bill, tgo

[keith_h]

What type of volume pedal and tuner so we can take a look at manuals and have better idea of their setup?

[lbpesq]

Dunlop mini volume pedal into Polytune II Mini.  I did a little more troubleshooting and found that engaging the footswitch on the tuner to turn it on and off causes an audible click through the amp.  I suspect the volume pedal is defective.

Bill, tgo

[David Houck]

The "manual" says that the AUX out has a TUNER/EXP switch inside the pedal; perhaps the problem is in the switch.  Maybe a short.

[lbpesq]

Yea, I cracked it open and the switch was set to "tuner".  Hearing Mica in the back of my head, I exercised it a couple of times just to make sure.  No effect.  I'm thinking I should try it with a different cable and with a different tuner to really isolate the culprit. 

Bill, tgo

[keith_h]

Was this the first time you've tried this?

Are you using the power supply from the pedal board for the tuner? If yes try an independent 9V, center negative power supply that can provide at least a 100mA. It could be the tuner isn't getting enough juice. I've read the Polytune is pretty sensitive to low current. Their manual also recommends an isolated supply which you might not have if you are using the pedal board power.

From what I could find the Polytune is not buffered so the switch pop could be normal depending upon where it is in the pedal board. One thing to try is to put tuner at the beginning of the effects chain and not use the volume pedal's Aux out. This would also be a good test for the squeal.

[xlrogue6]

Power supplies and pedals don't all play nice together, even though theoretically they should. Assuming you're running both off of the same supply, try running one off a 9 volt battery or an individual wall wart and see if that fixes the problem.

[lbpesq]

The volume pedal is passive.  The tuner is running off isolated power from a Cioks Ciokolate power supply.  Nevertheless, when I remove the Cioks power and plug in a battery buddie to the tuner, the high-pitched tone mostly goes away, but I can still hear extraneous noise added to the signal.  It seems to me a tuner out should be an output only, and shouldn't be operating as an input to add noise to the signal.   I have emailed Dunlop.  Awaiting a response.

Bill, tgo

[pace]

I wouldn't run a passive split to tuner anywhere along the signal chain...
It's a pain, but if you run it off a buffered A/B/Y box, I imagine your problem will disappear.