Wah pedal fault finding help please

BigMonka

Hi folks,
I'm after some help with fault finding on a Cry Baby wah I've got. All help appreciated please!

Symptoms:
- There is no wah effect
- Guitar sound passes through to the amp just fine like its on bypass
- Clicking the switch on and off doesn't affect the tone at all

Checked so far:
- Power supply is fine (battery or PSU), voltages around the board seem about right
- Visual check shows no damage and the connections all seem firm
- Pedal motion and the pot is fine, the resistance on the pot seems to change as expected

Questions:
- What are common parts to fail?
- Might it be the clicky switch? How would you test it?
- I reckon the inductor or caps might be likely failure points but if one of those went bad wouldn't it still affect the sound compared to the bypassed tone?

ICBM

That sounds like it’s not switching at all. If the effect circuit is broken you either get no sound or a very strangled one.

Have you tried pressing the switch manually? ie with your finger/thumb under the pedal.

Quite often the switch will sound like it’s clicking even when it’s not being fully operated. If so, it may need adjusting for height, or if it doesn’t work at all, it will need replacing.

fastonebaz

When I took my faulty wah apart once I noticed a little screw in thr switch mechanism had come loose,  tightening it cured my fault. 

Funkfingers

Check the underside of the treadle for a compressible foam or rubber pad. This should align with the mechanical on/off switch and cushion the impact between the metal parts.

On some designs, if the pad is absent or out of position, the treadle no longer meets the switch properly at its lowest point of travel.

BigMonka

Thanks a lot for the input chaps. As the consensus seemed to be the switch I unsoldered (desoldered??) the bypass leg from the switch and bridged the other two contacts. It's now alive!

So the issue was the switch, and something internal as pressing it hard by hand made the clunking noise but didn't switch. So now I need to find a new switch, I'm guessing the height is quite important - can anyone point me in the direction of a suitably sized replacement please?

I was also wondering whether anyone has modded a wah to allow switching to make it a volume pedal? I'm thinking just use the pot as a passive volume control by a DPDT switch which switches the input and output of the pot between wah and bypass. Is this a crazy idea?

ICBM

BigMonka said:

So the issue was the switch, and something internal as pressing it hard by hand made the clunking noise but didn't switch. So now I need to find a new switch, I'm guessing the height is quite important - can anyone point me in the direction of a suitably sized replacement please?

Check there isn't a loose screw as fastonebaz said - some are screwed together and some rivetted. If it's screwed you will need a very narrow flat-blade screwdriver.

If it's definitely dead, what you can do is get a standard 3PDT (the blue ones), and if you fit it with one nut only on the inside, as far down the thread as possible, and the grip washer and the other nut on the outside, the height will be perfect - I've fitted quite a lot of them and it seems to work nicely.

You can then wire all three switch poles in parallel for maximum reliability, if you're just replacing a SPDT - the standard old Cry Baby switch - or you could convert the pedal to true bypass as well which is a bit more complex.

BigMonka said:

I was also wondering whether anyone has modded a wah to allow switching to make it a volume pedal? I'm thinking just use the pot as a passive volume control by a DPDT switch which switches the input and output of the pot between wah and bypass. Is this a crazy idea?

Unfortunately it won't work - the wah only operates the pot through a portion of its travel, and in the wrong direction to work as a volume control.

Funkfingers

The Morley PWV does the dual function thing. Great for saving “real estate” on a pedal board but annoying as **** if you like to leave the treadle cocked midway for a specific filter frequency effect.

I soon got fed up with mine.

ICBM

The little Hotone mini wah does as well, as did the old DOD wah/volume. Both these use a different method of control than the Cry Baby’s primitive rack and pinion gear turning a pot which is directly part of the wah circuit.

BigMonka

Thanks for the info guys, I'll just keep it as a wah then.
I may be back later for how to wire up the blue switch!