pulldown resistors for buff n blend

[sixstringphil]

I'm having some popping problems with a ggg bmp / buff n blend circuit. Here are the layouts...

http://www.aronnelson.com/gallery/main.php/v/BarcodeVeroLayouts/album120/buffnblendPCB.gif.html
http://www.generalguitargadgets.com/pdf/ggg_bmp_grus_lo.pdf

And I use this 3pdt switching... (blue switches from Aron)
http://www.dazatronyx.com/support/true-bypass-technique.pdf

The popping is very loud and eventually fades away if you keep switching back and forth. I added a 1M pulldown resistor to the input of the blender, but it didn't help. I'd like to try adding one to the output, but wasn't sure where it would go. The output is lug two of the blend pot. Should I just put the resistor between lug two and a ground point? I've verified that the electros in both the BMP and Blender are oriented correctly. I reasoned that there was no reason to put pulldowns in the BMP circuit since it inputs and outputs from/to the blender, right?

[Barcode80]

sounds like a leaky input or output cap in the blender OR in the muff. replace those first.

[petemoore]

  Wherever there's an input or output capacitor going to contact/no contact point, you need a 'drain' resistor 'pulldown' resistor to bleed off any charge that may build up, or that large charge [compared to nothing or your guitar output] makes a pop when the signal path gets hit by it, the sudden discharge then being amplified.
  Count each cap to signal switch points there are in your project, be sure each cap/switch lug is referenced to ground with large resistor.

[sixstringphil]

Pulldowns on input/output of blender are no help. Another observation: When I have the circuit on, and then unplug power, the popping is VERY loud if I switch the circuit on and off with no power supply connected. Also, I'm wondering if my amp might have something to do with this. I seem to have the same problem with several other pedals. When I measure DC on the guitar cable plugged directly into the amp, I'm reading .3mV. Is that enough to matter?

[John Lyons]

That's nothing really.
What do you get when you measure the in/out jack tips when the pedal is bypassed/enganged?
If you get anything over more than .25v then the pulldowns are doing their job.
Maybe a backward cap?

John

[sixstringphil]

Engaged:
Input: 0v
Output: 0v

Bypassed: meter will not stay still. Maybe it's just my meter, but when it's set on DC it jumps around 100-200mV when the probes aren't touching anything. When I put it on the pedal in/out it starts slowly going up.  Is that normal?

[John Lyons]

There was a typo in my last post
I meant to say:
"If you get anything over more than .25v then the pulldowns are'nt doing their job."

What voltage does it go up to?
The voltage will build up
in the caps if the Pulldowns aren't working.
They bleed voltage to ground...

Just looked at the blender schematic.
There is a 100K to ground resistor so the output
should bleed voltage to ground at that point.
Putting a puldown here won't help with popping.

If you get voltage at the output then check the
100K resistor to make sure it's solidly connected to ground.

[sixstringphil]

Thanks John. I see the 100k pulldowns on both the clean and fx output on the blender, so I took off the 1M resistor I had put at the output. I'm starting to think this could be static related. Our house is very dry from running the heat so much lately. It wasn't popping yesterday, so I went ahead and gave it to my friend to try out. I guess if it pops enough to be a problem he'll let me know. Still not sure why I wasn't ever able to get a steady reading on my meter when the pedal was bypassed.