Anyone know where I can find a GCB-95 version E schematic?

playas

Well-known member
There are lots of wah schematics out there but I can´t locate one for that particular model.
Alternatively is anyone familiar enough with the different models that knows what the parts values are?

I´ve already Googled this and searched before posting (but the search function isn´t working).

What I´m looking for is a schematic for my Dunlop wah wah before I start modding it - once some parts arrive in the post.



If I can´t find one it´s not the end of the world as there are other dunlop schematics although definitely slightly different, as well as schematics for Vox / Clyde McCoy style wahs.

I imagine mine is similar to the other GCB-95 schematics I´ve found but without the extra (input buffer? - I´m no expert) section that aren´t in the Vox style wahs. Without that extra section it seems to be a fairly standard design apart from value changes.

My overall plan is add a few trim pots (or at least to replace the existing Q resistor) and also try to get a closer approximation to the general sound of a vox style wah...but I´ve no idea what the stock cap values are in my own as a starting point. (Apart from 2 electrolytics that look like 100uF and 2.2uF)

The transistors look like they may be 2 x ITT3904 rather than the 1x MPSA13 and 2 x MPSA18 in the other dunlop schematics I found. I have a few BC109s lying around that I can replace them with but I don´t think that´ll be necessary and will stick with one change at a time in any case.

Here´s a link to the closest dunlop schematic I´ve come across
http://fuzzcentral.ssguitar.com/schematics/crybaby.gif



What I am guessing is that most of the circuit before the 68k resistor 0.01uF pair leading to the base of the first MPSA18 is what is missing in mine.


If worst comes to worst I will sit down and try and figure it out by following the PCB traces and assuming the cap values correspond to the schematic in the link, but that seems more prone to mistakes.
 
Re: Anyone know where I can find a GCB-95 version E schematic?

Mine is a Rev E. There is no buffer. Easy to mod. Schematic is the same as earlier ones for the most part.

Check these page out. http://stinkfoot.se/archives/546
http://stinkfoot.se/archives/549

I'll read over this again later and give more input. Getting ready for a bday party but wanted to get you something.

Be careful when desoldering the components. The solder pads can lift easy. Not the end of the world if one does. Just fly a lead from the component leg to the next pad that it's supposed to go to.
 
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Re: Anyone know where I can find a GCB-95 version E schematic?

Thanks for the links.

Enjoy the party.
 
Re: Anyone know where I can find a GCB-95 version E schematic?

Thanks. It's a big one too. Our baby girl's 1st birthday was on the 3rd. Better to have the party today.

The Rev E board pics on that site are actually mine that I sent to him to add to it. He helped me wire mine up for true bypass.
 
Re: Anyone know where I can find a GCB-95 version E schematic?

Thanks. It's a big one too. Our baby girl's 1st birthday was on the 3rd. Better to have the party today.

In that case I hope you´re not too tired running around to enjoy it. I´m sure she´ll have a great time either way.


The Rev E board pics on that site are actually mine that I sent to him to add to it. He helped me wire mine up for true bypass.

I did wonder alright when I saw that he mentioned Erik
 
Re: Anyone know where I can find a GCB-95 version E schematic?

After some searching and reaching in to my memory, I came across this schematic (same as the one you posted the link to in the first post). From what I recall, it is the same as the Rev E Crybaby. There may be one or two component differences but there's no buffer in the schematic so that keeps it down to the circuit itself.

I changed the Q resistor to 68K and even swapped out the inductor for an Area 51 inductor. Made a HUGE difference in the sound. The pot was changed as well with one from Area 51. I don't think I changed the sweep cap. I know I tried it but can't remember if I left it that way. It was almost 10 years ago. :)

crybaby.jpg
 
Re: Anyone know where I can find a GCB-95 version E schematic?

I drew out a schematic based on that which I think fits my wah correctly. From that I have figured out everything except for the non electrolytic caps, so I´ll go on the basis that the values are the same.

Some of the other values are a bit different, but not too far off. Mine is also missing everything before the 68K resistor connected to the base of the MPSA13 via the 0.01uF. (What I guess is an input buffer) as I mentioned earlier.

My parts have arrived now so once I have the time to get stuck in I´ll have a go at some mods.

BTW I got a couple of inductors to try out. Am I right in thinking they are non-polarised and don´t need to be oriented any way in particular? One of them, a yellow Fasel has a green mark beside one of the legs. The other doesn´t have any distinguishing marks, nor does the stock inductor.
 
Re: Anyone know where I can find a GCB-95 version E schematic?

Cool. This circuit is really easy to work with. You are right that it does not have the input buffer. Not sure about the yellow Fasel marking. When I got the Area 51 inductor for mine, I just lined it up with the holes and soldered it in to place.
 
Re: Anyone know where I can find a GCB-95 version E schematic?

In case it´s of use to anyone else, this is what I think approximates the circuit of my wah (GCB-95 revision E)

wah schematic.jpg
 
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