Pearl OD-5 question

[boogietube]

I have a friend who has an OD-5.
He claims this:

" I have an old Pearl OD-05 pedal that has a parametric eq in it that is killer.Only issue is that for some strange reason the pedal has a mix of effected and non effected signal ..It isn't supposed to do that.. I think somethin is awry in the circuits.
Any ideas? "

Here's the schem:
http://topopiccione.atspace.com/pjimages/PearlOD5.old.gif

The only thing that I can see is R16 and R17 have separate signals recombining at pin 2 of IC2. At R16, the signal appears to have  eq,  and  R17 appears to have an un-eq'd signal.
Am I correct here? Would putting a dual 10k pot in that position make for a blend control? or, simply reducing or increasing one of the resistor values?

[boogietube]

bump..

[CynicalMan]

Link is broken.

[boogietube]

Here it is:

http://topopiccione.atspace.com/pjimages/PearlOD5.sch.gif

Help!!

[CynicalMan]

It just redirects me to www.atspace.com/dedicated-web-server-hosting-domain-articles-news/basics.html

[boogietube]

Here's the site:

http://topopiccione.atspace.com/projects.html

It's the Pearl OD-5

[boogietube]

I click and get no problem on the second link.

[boogietube]

Please someone help!

[Rodgre]

If it's a Tube Screamer-type pedal, those also have a little bit of clean signal blended in. I always thought that's why they worked so well through an already-broken-up tube amp and sounded like crap through clean solid state amps.



Roger

[boogietube]

Thanks, but please read the question. 120 + views and nobody can help? I want to know if the blend in this pedal could be altered?

[Mark Hammer]

Hi Sean,

There IS no blend in this pedal that I can see from the schematic linked to.  Initially, I was going to say that R16 provides a parallel path, but on second glance I realized that it is simply part of the resonant EQ circuit that precedes the clipping section.

Note that the final common pathway to the clipping section is via C10.  If you can find a way for the unclipped signal to bypass the clipping stage in that schematic, you're a better man than I.

Now, what is missing from Alex's nicely redrawn schematic is the electronic switching.  Seems to me that your friend is experiencing the same problem that crops up in the odd pedal now and then where the FET that enables/lifts the dry signal doesn't switch completely off.  In short, what we don't see in the picture is likely where the bleedthrough issue is located.

[boogietube]

Thanks, Mark. I was getting desperate.
Here's the original schem with the electronic switching:
http://i94.photobucket.com/albums/l86/boogietube/PearlOD5old.gif

[slacker]

To test if there's a problem I would do this. Disconnect the wire from the wiper of the "output level" pot, this is to disconnect it from the switching. Then listen to the signal at the wiper of the pot, if that still sounds like it's got clean mixed with the dirty signal then that's just what the pedal sounds like and there's nothing wrong with it. Tube Screamer type pedals like this can sound like they are mixing clean with the dirty because of how the clipping works.

To test the switching reconnect the wire and turn the volume all the way down and then set the pedal to "on", you should get silence from the output. If you can hear some clean signal it means there's a problem with the switching of the clean signal. If you put the pedal in bypass and turn the volume all the way up and you can hear the effect then there's a problem with the switching of the effected signal.

[Mark Hammer]

Looking at the entire schematic, it seems the obvious solution is to swap the existing 4007 chip for a new one.