Oscillation problem

[Harris529]

Greetings!  First time poster here.  I have a strange oscillation problem in a bsiab II.  I'm fairly new to pedal building but I've been building amps for a long  time and know the importance of lead dress....particularly in higher gain circuits.    In this pedal, if you turn up the volume and gain, it is still reasonably quiet.   There is some hiss, but nothing out of the ordinary.  However, at any level, if you turn down the volume on the guitar, the pedal  produce a high pitched note.  The problem is even more pronounced if I put this on a pedalboard with pedals in front of it...whether they are on or off.  Any help/advice you can give me will be much appreciated.

Thanks!

[PRR]

> if you turn down the volume on the guitar, the pedal  produce a high pitched note

Shield the wire from the input jack.

[Harris529]

I ran shielded wire from the input to the switch and from the switch to the board.  One end of each shield is grounded.   The oscillation no longer occurs with the guitar only, but is now worse on the pedalboard.

Thanks!

[Harris529]

Sorry guys.  I'm gonna have to give this a bump.  This is driving me crazy and I am out of ideas.  Anyone else have any?

Thanks!!!

[PRR]

Try 20K to 50K in series with the input jack.

I say 50:50 chance it gets worse. Problems like this can be TOUGH.

[Harris529]

It's fixed.  I'm really pleased to have this one behind me.  It was not the BSIABII....it was a ground loop created by the tube screamer clone in front of it.  It does not use isolated jacks.  I reworked the grounding in that pedal and the oscillation is gone.  Thanks a ton for the suggestions!!!!!