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I Think I killed my Crybaby...

Started by Gyrofist, February 10, 2011, 06:16:29 AM

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Gyrofist

So here's the thing, I was tired of going through so many batteries with my Original Crybaby wah (GCB-95), so, since it doesn't have a DC jack, I tried using the one adapter I have. It's a sort of universal adapter thing, with switchable voltage (I used 9V of course), and switchable polarity, and I used the battery clip adapter to put that in place of the battery.
The thing is though, I think that I may have accidentally used the wrong polarity and killed my pedal, because now it won't work. The bypass works fine, but when switched on the effect doesn't really do anything. So I'm wondering, how exactly would I go about figuring out what's gone wrong with it? I know that resistors have no directionality, but capacitors, transistors and diodes do, if I'm not mistaken? Would it just be best for me to replace all of the capacitors, transistors and diodes, just to be on the safe side? That would let me avoid having to test it, I think. I'm just wondering though, I've tried to find the schematics for this, but everyone else's Original Crybabys seem to be set up differently. And there's one capacitor in my wah that has no values on it (the large radial one), so I don't know what I would replace it with.
Any help with this whole situation would be appreciated.

jkokura

Not all caps are directional, just some. Chances are low you blew a cap. A diode or transistor is much more likely. Perhaps both.

Which crybaby version is it? It should have a letter.

Jacob
JMK Pedals - Custom Pedal Creations
JMK PCBs *New Website*
pedal company - youtube - facebook - Used Pedals

stecykmi

doh, this is why circuit designers should also include reverse polarity protection diodes, even for designs without DC jacks.


madbean

If it does have reverse polarity protection, it might be a simple as replacing the one diode. You could always audio probe it to see what happens at the first transistor. I don't think it will be too painful to fix.

Mark_McQ

Good excuse to replace some of the caps and resistors with better quality ones too.

madbean

#5
There are ton of replacement crybaby PCBs on the eBay, too. But, I doubt it will come to that.

Gyrofist

Quote from: jkokura on February 10, 2011, 06:48:07 AM
Not all caps are directional, just some. Chances are low you blew a cap. A diode or transistor is much more likely. Perhaps both.

Which crybaby version is it? It should have a letter.

Jacob

All I know is that it's an Original Crybaby, Model GCB-95, and that the serial number is CB071295. I can find two transistors, but for some reason I can't really find any diodes, does that make any sense?

jkokura

No. You'll need to take some pictures for us.

Jacob
JMK Pedals - Custom Pedal Creations
JMK PCBs *New Website*
pedal company - youtube - facebook - Used Pedals

Mark_McQ

There's only one diode. It should be just next to the DC jack on the board.

Gyrofist

Quote from: Mark_McQ on February 11, 2011, 10:09:19 AM
There's only one diode. It should be just next to the DC jack on the board.

It would be easy to find...if I had a DC jack. I think mine's from before the DC jack was standard on the "Original Crybaby". With that being the case, would it mean that I don't even have a diode?

Gyrofist

So I'll try to attach some photos, but I'm new to this whole forum thing, so I don't know exactly how it works, so we'll see.


Hopefully that works. The one picture I have's at http://img225.imageshack.us/i/p1050298j.jpg/
I'll try to get some better photos once I get home. Hopefully this'll work. Sorry about my newbieness by the way, when it comes to computers I'm horrible.

plesur

You've got an old circuit there, they don't have any diodes in them. have a look at this:
http://www.geofex.com/article_folders/wahpedl/wahped.htm

Your circuit should be very similar.

As said by previous posters, you've probably blown the electrolytic cap or one of the transistors. The 'big cap' is the inductor, you won't have blown that.

Build an audio probe, see here:
http://www.diystompboxes.com/pedals/debug.html
and check the circuit to see where the signal stops when it's powered on, the part before that is the most likely to be your culprit.

Good luck!