Zakk Wylde Crybaby Wah debugging help?

[vigilante397]

I picked this up cheap from a local music store that lost their Dunlop dealer status so they can't send it back for repairs, figuring it would be something simple. Unfortunately I pulled it open and couldn't see anything wrong with it, it just doesn't work. It's doing the old "working on bypass but no wah" trick.

I'm aware of the "rules of asking for help," but it is my understanding that wahs are a different beast. So rather than say "it's broken, how do I fix it?" I'd like to ask what to start looking for. Obviously there aren't any ICs to check voltages of, though I suppose getting transistor voltages would be a good place to start. Would voltages in and out of the inductor help? Not really sure what to look for here. Suggestions?

[italianguy63]

Hey Nathan!

There are definitely folks here that can help you.  I would suggest getting some voltages and posting.

Do you have a schematic for it?  It is the same as the regular Crybaby.  The difference on the ZW model is the sweep cap. is different.  I believe it is C7.  Instead of .01uF, it is .022uF on the ZW.  The sweep cap. is the one off the back of the inductor.

MC

[vigilante397]

I can definitely do that. I'll get voltages of the transistors for sure, are there any other voltages that would be helpful to get?

[joegagan]

check continuity from wire termination @ off board components & the underside of the header. these term clips can be funny. if you lose signal in the wire-to-term clip connection, try wiggling a small blunt object in there to push the wire in harder & maybe re-make the connection -this works most of the time.

also, if anyone has ever stepped on the power plug, the jcak can have an open acorss the normally closed hot pins. check continuity there.

the jacks can be problemtic, check them as well

check switch for continuity in the wah position.


it is VERY rare that it isn't one of the above.

[vigilante397]

I was hoping Joe would be around

Unfortunately it seems to be a little weird. I checked continuity with my DMM at the offboard components with the header, everything was good. Power jack looks fine, doesn't seem to be any problem there. Checked input and output jacks, both are fine. The switch turned out to be a problem, unfortunately not the problem. There was no continuity at the wah stage of the switch, so I bypassed the switch and took the wah side wires (blue) and jumped them straight to the common (green) as the bypass (purple) is working just fine.

When I did so, I got a rather interesting result: with the pedal all the way forward there is no sound, but as I rock slowly backward it starts to oscillate and give a lovely noise maker that starts moderately high pitched and gets lower pitched the further I go back.

Further thoughts? Is this a point at which pictures and voltages become helpful?

[joegagan]

i think you may have your green and purple crossed. the blue and purple are the two that connect to make wah sounds. green is input.

[vigilante397]

i think you may have your green and purple crossed. the blue and purple are the two that connect to make wah sounds. green is input.

Learned something new I misunderstood the way the SPDT switches worked in Crbabys (Cybabies?). I tried shorting the blue to the purple to bypass the buffer and successfully got a very loud hum with wah functionality rocking the pedal changed the tone of the hum. Unfortunately no guitar signal. So I tried putting everything back on the switch with my new understanding of how the switch works, everything checked out for connectivity with the multimeter, plugged it in and the bypass still works perfectly, but when I hit the switch and I'm supposed to have wah I have silence instead. So I thought maybe the switch is still bad and I replaced it with a 3PDT (only footswitch I had laying around) and just used one column, same result. Getting discouraged

What else can I check to find (or at least narrow down) the problem?

[italianguy63]

Nathan--

eMail sent, with big attachment.  Let me know if you get it.

MC

[vigilante397]

eMail sent, with big attachment.  Let me know if you get it.

Email received, thanks Mark. I've had the GCB-95 on my own board for a while now (one of the few non-DIY pedals on my board) and have been considering several mods I had heard about, and I think I might finally do them.

For the Zakk Wylde wah I'm working on I would like to keep it as stock as possible as I've heard the changes made from the original Crybaby are very good, but if I can't seem to make it work I am considering switching it to true bypass because it seems like that might make it easier to debug maybe?

[Govmnt_Lacky]

Im gonna go with the old standby:

Someone plugged in the wrong adaptor and fried something.