Wah issue : pop when changing the sweep...

[jaman]

Hello,

I would be grateful if anyone could help me fix the following problem :

I have put a rotary switch to my wah, to change the capacitor which is responsible for the sweep range...

but when I change the cap I have a big irritating pop !

I tried installing a 2x 4,7M resistors between the 2 legs of each cap and to the ground...but nothing...

any idea ?

ps -  I hope I made you understand my problem...my engilsh isn't good enough ( I am Greek... )

[jonathan perez]

all mine do too...when the wah is on...

[jaman]

all mine do too...when the wah is on...

I have played with a Crybaby 535Q (i think) which has also a rotary for the sweep and no pop appears...

I should have open it and see the trick...

[Paul Perry (Frostwave)]

A pop is generated whenever the input to a stage is switched between two points with different DC voltage on them.
Without looking at the circuit, I suspect that the caps that are switched, charge up when switched in & when switched out, the DC leaks away.
So I think the 1M resistors are being put in the wrong place.. I'd put the 1M (or similar high value) between the caps.
The 1M will be too high to affect the operation of the wah, but enough to counteract the leakage.
Let me know how you get on!

[jaman]

A pop is generated whenever the input to a stage is switched between two points with different DC voltage on them.
Without looking at the circuit, I suspect that the caps that are switched, charge up when switched in & when switched out, the DC leaks away.
So I think the 1M resistors are being put in the wrong place.. I'd put the 1M (or similar high value) between the caps.
The 1M will be too high to affect the operation of the wah, but enough to counteract the leakage.
Let me know how you get on!

This is exactly what it happens...

What exactly do you mean by "I'd put the 1M (or similar high value) between the caps" ?

[jaman]

Any other suggestions ?