New booster build making other effects pop

[PGS412]

Hi,

I've just finished installing the Mosfet booster into my Budda Wah. I inserted the circuit between the wah stomp switch and output jack so I can still use the Mosfet boost when the wah is switched off.

Everything works/sounds great but I am having a drama where every other effect on my board creates a pop when the Mosfet boost is on, even switching my guitar pick up selector causes a pop. When it is switched off it's out of the circuit & everything is ok, no popping.

I used the 10M input pulldown resistor & the 1M output pull down resistor. The PCB is grounded inside the Wah enclosure & switched on via a 3PDT toggle switch installed on the side of the wah.

Cheers for any replies or help!

[R.G.]

Pulldown resistors only work when the input and output capacitors are in place, correctly oriented, and not shorted or bypassed by wiring errors.

A system popping with pulldowns in place is indicative that there is DC on either the input or output. You can (usually) measure from ground to input and/or output with your voltmeter and find this.

[PGS412]

Thanks,
When i get home i'll measure the DC on the Input and Output & post back here 

[PGS412]

I measured the DC votage on the input & output to ground (With the pedal on), heres what I had come up:
Buffer input - 2.77vdc
Buffer ouput - 0.79vdc

I tested the wah also & came up with:
Wah input - 0.01vdc
Wah ouptu - 0.05vdc

Should i go for a lower value pulldown resistor on the input or maybe swap the input cap first?

[Ronsonic]

I'd replace the caps. 10M for a pull down is larger than it needs to be, but ....

[R.G.]

I measured the DC votage on the input & output to ground (With the pedal on), heres what I had come up:
Buffer input - 2.77vdc
Buffer ouput - 0.79vdc

Your input and possibly your output capacitor is either (a) bad and leaking or (b) being leaked around by soldering, connections, or wiring.

I tested the wah also & came up with:
Wah input - 0.01vdc
Wah ouptu - 0.05vdc

10mV is OK. 50mV is high, but you'll likely get away with it. 0.8V and 2.77V will make bad, bad pops.

Should i go for a lower value pulldown resistor on the input or maybe swap the input cap first?

Your pulldowns are not your problem. Go for the caps - but do not forget that improper installation and soldering can make a perfect cap look bad.

[PGS412]

Cheers for the replies,
I'm definitely suspecting the caps after your recommendations, the solder & connections are all ok.

I'll swap the input & output caps tonight & see how it goes.

[R.G.]

If the input and/or output caps are polarized - they will have "+" or "-" marks or both if so - then they simply must be installed the right way round, or even good caps will leak.

[PGS412]

Thanks for the info, but i didn't see the polarized cap markings on the Mosfet boost schematic...

Would I be right with the orientation of In signal >'-' Input cap
& Output Cap would be non polarized?

[PGS412]

Just swapped over the input & output caps with non polarized MKT caps. Still popping =(

I'm measuring 2.05v on the input to ground & 1.8v on the output...

I've double checked all wiring & all solder connections look good & test ok. Is it possible that being in the wah housing is just not going to work?

[R.G.]

Just swapped over the input & output caps with non polarized MKT caps. Still popping =(
I'm measuring 2.05v on the input to ground & 1.8v on the output...
I've double checked all wiring & all solder connections look good & test ok. Is it possible that being in the wah housing is just not going to work?

In general, no, it is not possible that being in the wah housing is just not going to work. It can be made to work.

However, you're now officially past the 'oh, here's a quick question' part of debugging. Go read and follow "Debugging: What to do when it doesn't work".

[PGS412]

Will do, I appreciate the help 

[Philippe]

Pulldown resistors only work when the input and output capacitors are in place, correctly oriented, and not shorted or bypassed by wiring errors.

*wondering why GGG only includes/provides for an input pulldown on most of their kits?*