Troubleshooting my Seeing Eye Mod (Boss DS-1)

[kyledix]

Hi all, first post here--I searched and only found one seeing eye mod-related topic so if this has already been mentioned and I missed it, please let me know.

I've put together a few guitarpcb.com boards in the past year or so and today I decided to try the All Seeing Eye mod and ultra mods on my Boss DS-1 distortion pedal.  I basically followed these steps, though I checked Keeley's site often in the process.  I've gone through the steps and double checked my work but I seem to have a weird problem in testing.  Wondering if I made some sort of rookie error that is not obvious to me.

The pedal essentially "works" when plugged into a 9v OneSpot power supply, but only at high input.  If I turn down my guitar volume, or play on anything but my humbuckers, or as notes fade, I get kind of a 'dying battery' effect where the sound crackles and cuts out, almost like a badly-set noisegate.  The 'seeing eye' LED works and corresponds to the clipping I'm hearing, but it fades as the 'gate' occurs.  If I play pretty loud the distortion seems to sound pretty good, and all the knobs seem to do what they should.  Has anyone that's familiar with this mod encountered this problem?  I'd appreciate any help and would be glad to check some things with my multimeter if you think it would help.

Thanks!
Kyle

[PRR]

Link to plan you used.

Voltage readings. http://www.diystompboxes.com/wiki/index.php?title=Debugging

[kyledix]

Sorry, here's the link: http://www.instructables.com/id/Modify-Your-Boss-DS-1/

Sounds like the capacitor soldered to the underside of the board should reach across both diode solder joints (ie, eachlead of the capacitor is soldered to both D4 and D5 leads)... that's how mine's set up.  Could that be the problem?  I had a hard time finding clarification on this.  

Here's a picture I took: http://imgur.com/C3cOEXx

Will read and post voltages tomorrow.  Thanks!

[kyledix]

Link to plan you used.

Voltage readings. http://www.diystompboxes.com/wiki/index.php?title=Debugging

I followed links to this page, this sounds most like what I'm dealing with: http://www.geofex.com/fxdebug/bias_prob.htm

Sounds like I should take voltage readings from the transistors?

[PRR]

> the sound crackles and cuts out, almost like a badly-set noisegate.

Transistors are normally biased "half-on", so a signal can swing them more or less on, and replicate the sound wave.

When a transistor is biased nearly off, it will sound fine for large signals but garble and cut-out small signals.

That said... I'm not inclined to work-through a many-page Instructable project. They are good IF everything goes right. If anything goes wrong, we don't know what went wrong or what to do to find it.

Pardon a rude analogy: you ask a song-doctor for help with a song that isn't as good as it could be. You say "I put my ring finger on the 3rd string 5th fret. I put my pinkie finger on the 4th string 7th fret. I strum. Then I move my ring finger to...." The doctor wants a score/tab notation so he can quickly see what is going on and can focus in on any rough areas.

He's pulled-out and replaced a bunch of caps, and the LED. But it is difficult or impossible to figure out what they did, before and now. Without a schematic (an electronic "score") and perhaps some notion of what the "right" voltages are, this puzzle is too tough for me.

Basic fixin':

See if there is a better (more detailed techical) source of information than the Instructable pages.

Re-study all your solder joints for mis-connects, shorts, blobs, etc.

Go over the "put this cap there" list and see if it is exactly right.

UN-DO the "mod", put it back like the factory made it, and see if you get back to stock. This is drastic: constant re-re-modding is liable to bust-up the board and wires.