Dunlop - Cry Baby GCB-95: how to improve it for cheap

Zephios · Post by **Zephios** » 01 Nov 2012, 22:38

Hello FSB community.

I have recently bought a GCB-95 (Rev. G) off eBay for cheap, but upon receiving it the wah was very weak and nonexistant. I thought this was because of the pot that was old, so I replaced it.
After that the pedal seemed to work but whenever I would turn it on there would be a huge volume drop.
I looked on the internet to find some solution and someone said that the capacitors may be dying, so I've decided to just replace them all after reading this thread to improve the sound.

I've replaced 2x 10n and 2x 220n caps with Metallized Polyester Film Capacitors of the same values, but I am quite new to all of this so I don't really know if there is a difference between the old ones I had on it or these, since they come with
10nF 1000V and 220n 100V.

Once this was done I replaced the 4.7uf electrolytic capacitor and the 82k ohm resistor with a 3.3uf BP cap and the resistor with a "100K Ohm 0.25w Metal Film 1/4w Resistor 1%".
Part of the first post also mentioned the following: "replace them with a 3.3uf BP paralleled with a 680n film type (for close to 4uf) " This part I did not quite understand, and have done nothing with it either.

Lastly I've just put a new 220uF 16V Radial Electrolytic Capacitor instead of the old one since it was hanging a bit loose and looked damaged and replaced the 390 ohm resistor with a 510 ohm resistor.

Now once everything was back on, as soon as I hit the switch there is a loud POP noise, and when I start the wah up there is one loud noise that constantly goes on like a howl I guess(sounds like a mooooooooooooooooooooooooooooooooo sound).

Also, during the soldering the little steel ring underneath the circuit board came off kinda, does this cause any problems? It happened when I switched out the 390 ohm resistor for the 510 one.

Can anyone please help me with fixing this? Much appreciated.
Really want it to get it to work

I will get a picture on the circuit board if needed.

Kindest regards,

Zeph.

Bside2234 · Post by **Bside2234** » 01 Nov 2012, 23:22

This "little steel ring" - was it a solder pad or the metal on the board around where the mounting screw that holds the board to the enclosure is? Either way, the mounting hole is grounding the circuit so if it's gone, and all the grounds aren't connected in some way, then you will most likely get a noise. If a solder pad broke off, that needs to be repaired.

Zephios · Post by **Zephios** » 01 Nov 2012, 23:52

Bside2234 wrote:This "little steel ring" - was it a solder pad or the metal on the board around where the mounting screw that holds the board to the enclosure is? Either way, the mounting hole is grounding the circuit so if it's gone, and all the grounds aren't connected in some way, then you will most likely get a noise. If a solder pad broke off, that needs to be repaired.

It's the solder pad then, I assume you can buy this in any hardware shop/online? Will that just fix it all?

Bside2234 · Post by **Bside2234** » 02 Nov 2012, 00:03

Can you attach a picture of what broke? You can't buy solder pads at a hardware store!!!

Zephios · Post by **Zephios** » 02 Nov 2012, 00:45

Bside2234 wrote:Can you attach a picture of what broke? You can't buy solder pads at a hardware store!!!

Using this from another thread:

download/file.php?id=14149&mode=view

Basically a 'ring' like at C8 came off.

Zephios · Post by **Zephios** » 02 Nov 2012, 19:42

Zephios wrote:
Bside2234 wrote:Can you attach a picture of what broke? You can't buy solder pads at a hardware store!!!
Using this from another thread:

download/file.php?id=14149&mode=view

Basically a 'ring' like at C8 came off.

Bump.

Bside2234 · Post by **Bside2234** » 02 Nov 2012, 20:40

You need to:
1. Scrape the solder mask off the trace near where the solder pad broke off and solder the leg of the component that was supposed to be soldered there to the trace.
or
2. Solder a piece of wire from the leg of the component that was supposed to be soldered to the broke trace to the next component(s) that the leg would have connected to. Basically replacing the trace(s) from that broken solder pad with wire.

guitarburks · Post by **guitarburks** » 30 Nov 2012, 23:52

I did some of the mods listed here to my Crybaby, I did one mod at a time so that I could hear the difference with each. I don't remember exactly which mods I did but I remember doing resistor, gain, q mods and changing the inductor to a red Fasel. All mods were an improvement except for the gain mod, it added noise to the circuit and made it almost uncontrollable when used with any sort of drive/distortion pedal. So I undid the gain mod, ending up wit a nice, usable wah that promptly exploded at a gig!

I'm currently using a Wilson Rippah wah and it's my favorite wah I've ever played. I've been thinking about recreating the Wilson in the old Crybaby shell, finding the values of my favorite settings and recreating them without the external adjustments to get jumbled around while gigging. Should have a good usuable gig wah for cheap.

Post by **azrael** » 05 Jan 2013, 18:44

Any idea on where one can get a metal cap to place over the inductor, like they have on Budda Wahs?

Zen Arcade · Post by **Zen Arcade** » 12 Jan 2013, 23:12

I bought a used gcb-95 for cheap off ebay with the intent to mod it, and this is what I found inside. It looks like a homemade hackjob to me. The guy said he bought it in the early 90's - if it's not a fake, what revision is this? Some of the part values match the mods listed in this thread. The transistors (it only has 2) are 5117's. The inductor has no markings whatsoever.

B3ar · Post by **B3ar** » 13 Jan 2013, 02:29

Zen,

You've got a Rev. E. The 5117s are Dunlop house transistors, pretty standard before Rev. F. Rev. E is the last revision with hand-wired output jacks but the first with a power adapter jack.

Take a peak at the C/D revision stuff on the previous page of this thread, along with the Vox 847 layout also shown, to get an idea of how the layout matches to standard schematics. Board layout should be identical, component values may vary in a place or two.

Zen Arcade · Post by **Zen Arcade** » 14 Jan 2013, 16:23

Thanks man, that's just what I needed to know.

astrobass · Post by **astrobass** » 09 Mar 2013, 04:46

Today I did the gain mod, going from 390 to a pair of new 1K 1% resistors in parallel (so 500K ideally), and the sweep mod (going from 0.01 to 0.047uF), and a variation on the Q mod, I pulled the 33K ohm resistor, replaced it with a new 33K 1% resistor in series with a B25K pot so I could see what sounded best. Don't have a dremel to put a hole in the enclosure and expose the pot yet, but I'll get one eventually.

Did all of this with the intent of using it with my bass. Already it sounds a lot less thin due to the sweep mod and the bottom range of the sweep seems less noisy. Wasn't thinking and I didn't do a before recording to compare to the after recording (really wish I had).

I've looked at the FatWah mod, and it seems easy enough to reverse if I don't like it, but before I get started, can anyone describe what the difference is? I couldn't find any demos of it or anything on what to expect. Is it a good idea if you're using it with a bass or does it only really benefit guitars? Like does it tend to be noisy or muddy with a bass?

If I open it up again, I'm going to take out that pot and replace it with a B100K.

Fred_Garvin · Post by **Fred_Garvin** » 24 Apr 2013, 04:07

I don't want to offend people here but I have never found any difference sound wise in the type of material used when replacing caps in a wah. This also goes for replacing the 4.7uf cap for a 4uf, I've replaced one of my wahs with a 3.9uf tantalum and I didn't hear any difference whatsoever. Sorry, to all glue huffers and cork sniffers, but, I spent countless hours experimenting.

The most significant change one can do to make a awful sounding wah into an amazing one is to replace the god awful stock inductor that comes with the crybaby. I've experimented with loads of inductors and found the dunlop yellow fasel, sabbadius soul halo, and whipple were the best sounding and made a significant change to the overall sweep and vocal-ness of the wah.

The only other change I would suggest is the vocal mod, this sometimes brings a yucky wah to life but sometimes it doesn't and the inductor replacement is the only way to go. Lastly, there's one mod that doesn't require any parts at all, and that is simply to adjust the pot gear assembly throw, this can change the sweep dramatically, and this done with a simple phillips screw driver.

Lastly, don't get your shorts in a knot when selecting transistors, I've tried bc547, bc549, 2n5088, 2n5089, etc, etc. I tried high gains up to 800hfe down to 350hfe and didn't find any significant change in output or clarity. Any basic transistor between 350-400hfe would suffice or don't change them at all.

Just my monkey in the wrench...

CHEEZOR · Post by **CHEEZOR** » 25 Apr 2013, 18:11

Actually, I agree with most of what you said. I didn't notice any difference in transistors that I changed, but I thought the Sweep Cap mod was the most bang for your buck. One single cap and you can get rid of the horrible ice pick treble. But some people probably like the treble stock. To each their own. Anyways, thanks for sharing!

Fred_Garvin · Post by **Fred_Garvin** » 30 Apr 2013, 01:15

I do mind, the Dude minds. This will not stand, ya know, this aggression will not stand, man.

copperheadroads · Post by **copperheadroads** » 17 May 2013, 16:48

I have GCB-95 rev c (the one without pcb mounted jacks) & I wanted to do the true bypass mod & add a led & I'm not sure where wire them on the board.
I see quite a few instructions on how to do this on the newer models but not the rev c
It has the same board as posted on the previous page in this thread

B3ar · Post by **B3ar** » 19 May 2013, 16:13

copperheadroads wrote:I have GCB-95 rev c (the one without pcb mounted jacks) & I wanted to do the true bypass mod & add a led & I'm not sure where wire them on the board.
I see quite a few instructions on how to do this on the newer models but not the rev c
It has the same board as posted on the previous page in this thread

I can't vouch that the wire color codes correspond perfectly, but the Vox at the linky is supposed to have the same board layout as your Rev C, so the mod should work if you make sure it makes sense before you leap. http://www.fulltone.com/sites/default/f ... 47-mod.pdf

astrobass · Post by **astrobass** » 20 May 2013, 05:01

CHEEZOR wrote:[ Image ]
Actually, I agree with most of what you said. I didn't notice any difference in transistors that I changed, but I thought the Sweep Cap mod was the most bang for your buck. One single cap and you can get rid of the horrible ice pick treble. But some people probably like the treble stock. To each their own. Anyways, thanks for sharing!

When you're using a transistor that's biased properly for amplification, most should sound just about the same. The sweep cap mod completely changes the nature of the pedal, I used a 10 way rotary switch and used a range of caps from slightly smaller than the stock cap down to way larger than the stock cap.

The larger values DO have a bit of a volume drop out in the lower range of the sweep, and the larger you go the more of the sweep you'll see volume drop on.

The input cap swap is critical if you want to use it with a bass guitar. The bass rolloff on the input is severe with the stock cap.

Replacing the gain resistor with a B1K is totally worthwhile. The mods to replace the mid-range resistor and the vocal mod resistor with pots are also good, but much more subtle. I used a 33K+B100K for the vocal control, and a 1.8K + B1K for the mid range control. I would suggest doing these last, and only if you don't get what you want out of the sweep switch and the gain control. Even then, mid-range before vocal. The mid-range mod has a clearly noticeable effect on the pedal back position, the vocal range mod mostly affects the pedal forward position, but is less pronounced.

burninwordz · Post by **burninwordz** » 02 Jul 2013, 01:54

Hi how can I cancel a pop when I turn my crybaby pedal on and off ,I modded the pedal to truebypass and now I get a pop, thanks