Old CryBaby wah pedal nnot "wah-ing"

[Fred G.]

Hey all,

I'm attempting to repair a very old CryBaby wah pedal - looks to be an '80's model, maybe? Anyway, the pedal does not "wah" - when the pedal is turned on, I still get a full (but slightly thinner) guitar signal, but there is no wah effect when I rock the pedal back and forth. Put simply, the pedal works fine in bypass mode, and still puts out a signal when engaged, it just doesn't "wah".

I've built several amps, and I also do amplifer mods and repairs for the local mom 'n pop music store, but I've never ventured into effects repair. Can anybody take a stab at what might be the root of this particular problem? Also, any FX pedal troubleshooting hints and tips would be greatly appreciated!

Thanks in advance, everyone!

Fred G.

[The Dude]

Is it one of the wah's with a string wrapped around the pot shaft? If so, check that the string isn't broken, misaligned, or slipping. If that's it, you can buy string kits for them. If it's the gear system, check that the gear is actually turning the pot shaft and that something isn't loose.

[vintagekiki]

https://www.youtube.com/watch?v=N5z4IhwkdMk
Fulltone tells how to Install and adjust a wah wah Pot

https://www.youtube.com/watch?v=spjS-SjOmns
Adjust That Wah Pedal

https://www.youtube.com/watch?v=WwdQ48VdGrk
10 Minutes to Better Wah Tone!

https://www.youtube.com/watch?v=v0Ck195r468
Adjusting the potentiometer of your VOX V845 wah pedal

[Fred G.]

No, this one has "gears" - there's a toothed sleeve on the pot shaft that interlocks with a toothed rod attached to the foot pedal.

Vintagekiki - I've already watched several videos on removing and adjusting the pot. I'm more interested in troubleshooting, I'm not convinced the pot is bad, just yet. Mechanically, it "appears" sound, and when I measure it, it is indeed showing resistance changes when the pedal is cocked back and forth. I haven't had a lot of time to fiddle with it just yet, and whenever I take on something new and unfamiliar, I'll usually come here immediately to take advantage of the experience of those who've preceded me down this path (tips, tricks, gotchas, bewares), while I'm also snooping around the Internet to get up to speed, on my end.

Thanks guys!

[vintagekiki]

All wahs mostly have a toothed sleeve on the pot shaft, only the early Morley wah's is with string wrapped around the pot shaft.

[vintagekiki]

To check if the wah works, you have to separate the pot from the toothed sleeve, and then examine how the sound changes in the end positions of the pot. It is possible that someone before you misaligned the toothed sleeve so wah "thin" sounds.
Question.
Does the bypass sw on wah work properly.

[Fred G.]

It doesn't "wah" at all. It works fine in bypass; also appears to pass a very slightly attenuated and brighter signal when the pedal is turned on. It just will not "wah" with the rotation of the pot.

[vintagekiki]

Check that the pot is wired correctly, that the wires on the pot are not interchanged.
With the Ohm meter, check the correctness of the pot itself, whether it is working properly or is damaged, and then it interrupts.

https://elektrotanya.com/vox_v846_wah_1967_sch.pdf/download.html
_{VOX V846 WAH 1967 SCH}

[Fred G.]

The pot wiring is in all likelihood original. I know the owner personally, he wouldn't be screwing around inside it. He said it's sat around for several years, I'm more suspicious, now having read more, that it's possibly one of the two electrolytic caps that may have dried out.

Great article, from a guy who used to post here frequently in the 1990's:

http://www.geofex.com/article_folder...edl/wahped.htm

[Jazz P Bass]

Attached is a diagram that shows what does what.
Unfortunately, it can not be said what is wrong without proper troubleshooting.
You have the unit.
You must determine where the signal is failing.
Only then can we help with why.

[Fred G.]

I had that information before I posted here...I'm primarily interested in troubleshooting techniques for pedals, and tips/hints/gotchas about this specific model. Thanks.

[vintagekiki]

Troubleshooting techniques and tips / hints / gotchas about it is like traffic in a two-way street.
For dialogue mutual exchange of information is needed, and from your post, except from "very old CryBaby wah", it is still unknown about whom wah is talking about.
Often times the image of "Under the Hood" is enough as a basis for dialogue ...

[Helmholtz]

Sorry but I need to ask: Are you sure you didn't mix up pedal input and output jacks?

There are no special troubleshooting techniques for pedals. A wah is just a little amplifier with variable frequency dependent feedback, most using only 2 transistors.
Please identify pedal manufacturer and find appropriate schematic. The rest is routine: Measuring voltages, checking transistors, diodes, ecaps, inductor...

At least provide a good picture of the guts.

[52 Bill]

It would be helpful to know which version you have there. Does it have two or three transistors?

The crybaby is a very simple circuit, so basic troubleshooting would include testing the transistors, looking for broken wires/bad connections, a bad pot, etc.

There are two basic parts of the circuit, one an inverting and one non-inverting. If the pedal passes signal but does not wah, that would point to a problem in the second section of the circuit, the non-inverting part that feeds back an inverted signal to the first stage. This feedback causes the phase cancellation of frequencies that give the wah sound. If the feedback signal is not getting to the first stage there will be no effect. There is a 0.01uF cap that carries the signal from the second stage to the first. Check that cap and check the second transistor. Also check the pot to see that the signal is passing through it.

If the pot does have some effect on the signal like a slight volume change, then the filter components of the circuit may be bad. In that case, test the choke and the 3.9-4.7 uF cap to see that they are alright.

Hope this helps.

[Helmholtz]

Dunno what you mean with "phase cancellation".
A wah is an active LC resonant filter that boosts a variable frequency band. The opposite would be a notch filter.