Boss bypass problem

[shredgd]

Hi everyone,
I'm experiencing a problem with a Boss SD-1 pedal (which I won at a guitar competition and I don't like that much, btw). When the effect is bypassed there's a subtle ringing associated with single notes, which I realized to be a leakage of the effect into the dry signal (at least, this is the most reasonable conclusion). Does anyone know how to fix this problem? In other words, how can I improve a Boss pedal bypass?
Thank you in advance,

Giulio

[Peter Snowberg]

Hi Giulio,

Your absolute best bet would be to use a true bypass box to eliminate any contact with the circuit when it is off. A small box with a DPDT switch and four jacks will do wonders. This is also very useful if you want to place EQ before and/or after your distortion to shape it.

I don't have the schematic to your pedal, but I suspect that you either have a leaky FET in the switching or maybe another leaky part that is telling the FET that switches the effect output off to pass some signal.

Take care,
-Peter

[Marcos - Munky]

If the schematic helps, I have it in my PC. Send me a e-mail and I send it to you.

[Mike Nichting]

I had the same problem and here is what Rob Strand said to me:Perhaps try some lower VGS off JFETs, perhaps even a J201.

Before you do any serious modding I strongly recommend you do a * trial
test*: Completely remove the link/22k to the JFET on the distorted signal
path.  With this link pulled there can be no strange problems relating to
the distored path JFET. If the noise is still there then the problem isn't
related to the JFET, it is yet another problem hidden in there - most
likely supply decoupling or layout issue.  If it does remove the leakage
then by all means change the JFET

I replaced the 22K's with 1K's and it got rid of the bleddthrough. Not everyone has been that lucky tho.

Good luck,
Mike N.

[shredgd]

Thank you very much guys, I'll do those tests/mods as soon as I can!
However, I didn't understand well your test, Mike, between which components should I cut?

Giulio