My crybaby is a 1994 GCB-95
I bought it used.
My guitar signal is fine but when I step on the it to Wah it goes completely dead!
My battery reads 9.20 Volts (it's new)
As far as I know this Crybaby is totally Stock, although it has a HotPotz-II in it. I don't know if they came like that or not.
When I bought my CryBaby years ago it had a similar problem.
Ended up being a crack in a trace on the PCB.
I would start by checking if there's voltages where it should be like transistors.
Other than that a I would rig a signal going through it and see where it stops.
If you read the Technology of the Wha at GEO it also mentions caps a a possible problem.
Aharon
The traces on the board look perfict.
I have voltage at across all three transisitors although I'm not sure what they should be.
I'm now hunting down how to check the caps with my DMM.
Don't forget to check the switch or the output wire of the effect to the switch (which I think is a blue wire coming from the pot).
Adam
I checked the switch and and the wires from the back of the board.
Purple to green when the wah is off. It is good.
Switched the wah on and checked purple to blue and that is good also.
I continued to check the rest of the wires (black and yellow) from the solder point on the back of the board to the HotPotz II and they are good.
I'm back to hunting down how to check a cap.
I made an audio probe and trace the signal to first component (a diode I think) and the signal dropped way off.
I continued to trace the signal to the middle leg of the first transister (in the buffering area) and there was no signal from either outside leg of that transister.
Is that transister bad?
Almost no signal at the base, and NO signal at the emitter or collector? Busted tranny. I think the first component would be a resistor though, which would explain the loss of volume. Try replacing that transistor, without damaging the copper tracks. They tend to let go when you overheat them.
I'm having a similar problem but when I probed it the signal stopped after the first Cap of the buffer. I was getting a clear signal before it, but nothing but a pop when I connected it to a probe. Is it common for a cap like this to malfuction?
Cap problem. All you need do is replace that cap and you're hopefully back in business :)
Does the voltage of the cap matter?
Could I use a 50 volt .01uf cap?
Quote from: ZitoDoes the voltage of the cap matter?
Could I use a 50 volt .01uf cap?
That would be fine.
It wasn't the 0.01uf cap.
After replacing it (0.01uf), using the audio probe it had that same hollow sound and loss of volumn right up to the base of transister MPSA13 and no sound at the collector or emitter.
Time to order a MPSA13 and try again.
Well I got my parts and replaced the MPSA13 and still nothing past the center prong on the trany (base I think).
The voltage on the one side of the MPSA13 trany is 0.79. Does that sound correct?
I Changed over to the true bypass and got rid of the the input buffer.
I now have good sound in bypass but when I hit the switch I get just a faint thin sound and no Wah when I rock the pedal.
Suggestions?
QuoteTime to order a MPSA13 and try again.
Shouldn't that be an MPSA18 ?? An MPSA13 is a Darlington pair, with hFE of >5000. An alternative for an MPSA18 is a 2N5089. When you've got the right tanny in there, check that the base (middle leg) voltage on the first transistor is a reasonable value (something like 1.5 to 2 V). The emitter (left leg when looking at the flat face, I think) will be 0.7V less than the base. The collector (probably the right leg when looking at the flat face) will be more like 3 to 6V. There should be a small signal on the base and emitter and a very large signal on the collector.
The MPSA13 was in the input buffer and was removed when I changed over to the true bypass.
Q1 MPSA18
Bass voltage is 0.17V
Emitter voltage is 0.00
Collector voltage is 0.66
Q2 MPSA18
Bass voltage is 0.45
Emitter is 0.79
Collector is 0.00
Voltage after the wall wart plug and before the 1K resistor is 8.93V and after the 1K resistor it is 0.79
When I measured the 1K resistor with my DMM it read .974 ohms
Bumping this to the top.
I'm really lost here.
Still no Wah just a hollow sound in the wah position.
Since you already modded your's, use this as a reference, and double check that all your connections are correct:
http://homepage.ntlworld.com/s.castledine/greenfuz/wah.html
Fret Wire,
That is the exact link I used to mod my pedal. I removed the input buffer components as I thought it would be a much cleaner job. I rechecked the mod and it is perfect.
It seems as though I have a voltage problem as my voltages on the MPSA18s are no where near close to those posted by Brett earlier in this thread.
Following the neg. battery (black) wire to the board my voltage drops after the 1K resistor to 0.79V. Before the 1K resistor it is 8.93V. I removed and replace that resistor, but that didn't help.
I got this wah in non working condition and it would only work when the effect was bypassed. After I made the mod I got a very faint sound in the effect position but no wah effect.
I thought repairing and moding this wah would be a good place to start learning before I actually tried to build anything from scratch. I can't believe how good this board is and much I have learned from from the links and ALL the people who are helping me with this as I know less than nothing about this stuff.
OT. I live in Western New York.
I'll check the voltages on mine and compare. Western NY, huh? We got pounded with snow last nite!
When you get a chance, check your readings off the pot, both pedal up and down. Should go from about 9 ohms to 100k or 120k depending on which pot you have. Then check em' again at the wiring harness at the board.
Fret Wire,
I GOT IT!!!!!
After looking at that link again I saw that the battery wires were siwtched in the plug that plugs into the board. I changed them and now I can Wah.
I now have a scratchy pot, but I bet you never saw a person so happy to hear a scatchy pot. I'm soooo Pumped!!!
THANK YOU, THANK YOU, THANK YOU,
To ALL that Have Helped me THANK YOU.
Now I'm off to search these posts of the best Wah pot.
OT. We got lucky NO Snow last night, and I live near Lake Ont.
Life is good. No Snow and I got my Wah to Wah!
Great! Glad to hear it. You're Wah..ing and have true bypass! This is a good forum. It's like trying to fix your car over the phone.. hard, but these guys here do it time after time!
For pots, there are a few choices. Unless bad, I don't change em'. Between a pot and inductor, it's almost $50. There's other mods to try first. That site you already have is one of the best. To me, true bypass comes first (best bang for the buck), then the various voicing mods, then if you want you can try pots and inductors.
For a stock replacement, I like the hotpotz I over the hotpotz II. It has a wider range up to 120k vs. the II (100k). It also has solder lugs instead of those posts. For aftermarket, the Fulltone is nice. I don't like the plastic pots. Many times, the pots arent indexed right from the factory. You wont get the full range. Here's a few adj. links
http://www.happybob.com/marc/pot_adjustment_procedure.htm
http://www.realmccoycustom.com/ADJUSTMENTHELP.htm
another good wah site: pay attention to the pot section, a trick on how to fix a scratchy wah pot.
http://www.geofex.com/index.htm
Fulltone site:
http://www.fulltone.com/stpframe.html
Fret Wire,
Thanx for the links. I feel like I have been living between here and Geofex. These two places just light me up!!!
Once again Thank you all for the help.
Your Welcome. It is fun when it all comes together! BTW, I live between Syracuse and Rochester.
Your mission, if you choose to accept it, is to abduct former MXR employee's (Rochester), and probe them for schematics! lol :twisted:
If you're gonna shop for pots, look at Small Bear (at very bottom of stock list). If you're gonna start building pedals, you'll end up there anyways:
http://www.smallbearelec.com/Ordering/Stocklist.htm
As you can see, the Fulltone pot is the cheapest, and people like it. Check the Fulltone link for more info.
On my earlier post, I accidentally put the same pot adj. link in twice. I fixed that and put in a link for adjusting pedal tension.