Popping!?

[gtrmac]

I get a loud pop when I some of my DIY FX and I'm not sure why. One culprit is the PT-80 and this one shows a pulldown resistor after the output cap so this is puzzling.

Another popping machine is my Vox WAH which has been modded with a DPDT switch. It seems to me that the caps have a path to ground through the pot so I'm not sure why this one is popping either.

Any ideas?

[gez]

Check for DC voltage on the output with a meter.  Your output caps (probably electrolytic) might be leaky.  If so replace (tantalum would be my choice).  

Check the orientation of your caps too as this might be the reason they leaked in the first place (if this is the problem).

Also, what is the size of the pull-down resistor on the PT-80 effect?

[puretube]

got pulldown-R on in-put side, too?

[gtrmac]

OK-

I replaced the electro in the WAH again and I forgot to check the switch pop last night.

As for the PT-80 there is a 1M R on the output, after the blocking cap which is a film type. The schematic shows a 1M R  going to V REF after the input cap so I guess I'll have to check out the effect of a res to ground in front also.

Thanks for the replies  

[puretube]

that PT-80 1M to Vb is probby for bias - doesn`t help popping.
the pop-R gotta face the switch-side of the cap!

[gtrmac]

Thanks, I'll stick one in there and see what happens.