Issue with pedal input jack

[squirrel]

Hey there,
Having an input problem with a pedal I recently finished. If a normal (mono) guitar cable is inserted into the input (stereo) jack I get a really bad/loud ground hum noise with the effect mixed in. This happens when a guitar is plugged in or not. If I then plug in a stereo cable and hook that up to an ipod or something similar the effect works fine and there is no hum at all. If anyone can suggest anything that might help I would really appreciate it as the effect is too noisy to be used right now.

Thanks Heaps

[petemoore]

  I'm not clear what the wiring you're doing does/looks like.
  But Having a DMM, pencil/paper handy, a Stereo jack, a mono jack and a mono plug, and using your eyes to trace where the tip wiper and other jack connections 'looklike' they go, then verifying that with the meter helps sort out what 'that' particular type of jack actually 'does'.
  Often enough the mistake is confusion about a 3 lug switched mono jack trying to do the job a 3lug 'TRS' stereo jack.
  Say it's the input jack PS kill trick, so the I jack tip only carries signal to circuit [via TB switch or not], ground is made at the sleeve to everything except the battery, the battery only gets to see ground when the mono plug connects the ring/sleeve wipers of a stereo jack.

[squirrel]

The pedal is using a stereo jack for power switching. I'm working on a tremulous bear from smallbear. I thought I would see if anyone on this board could help out because I feel I've already bugged SD enough about the pedal. What I'm finding is that the noise from the pedal sounds like ground hum but I've checked all my connections on and off the board and can't find anything wrong. I juat can't figure out why when a stereo source is plugged into the input there is no hum.
Anyone got a suggestion?

Thanks,

Squirrel

[GibsonGM]

well, I can't do better than petemoore 

I'd suspect the problem lies in how the ring/sleeve are connected, MAYBE, without seeing it.   

1)assure that the tip goes to the circuit input (or bypass switch - and then make sure the switch goes to ckt input properly)
2) determine where the ring and sleeve connections are going to.  Make note of where B- (ground) is connected in relation to your ground connections to the rest of the ckt.    Plugging in a mono jack, test for continuity between ring & sleeve...and NO cont. to tip.   I suspect a short in there somewhere connecting tip to ground.   BTW, assure yourself that you know which tab is ring, tip, and sleeve - and how the jack is supposed to engage them - or you'll get nowhere, lol. 

Provided the ckt is functioning correctly otherwise, you have a good chance of isolating the problem right there.  If this doesn't help, the problem could be at the board, but 1st things 1st.   Let us know how you make out!