Help with Crybaby wah mod

[kevn]

Greetings, I'm new to the forum & new to modding pedals. My first attempt will be a Dunlop crybaby gcb-95. I have Brian Wamplers mod book & have also looked at this site:

http://members01.chello.se/pastorn/fx/mods/dunlop.htm

Brians mod appears to id the components on newer boards (rev f,g h??) and I'm not sure where these components are on mine!  The link above has a photo of the revE board, but also only identifies the components on the newer boards. If someone could somehow describe where the components are that are to be modded I would greatly appreciate it.

[cmat]

Do you have a picture of your board?

[kevn]

If you follow the link above and go to the section "step 2c. rev E wahs (1990)" there is a picture of a rev E board that looks identical to mine.
Thanks - Kevin

[vanhansen]

Kevin, those photos were provided by me to Andreas, at least the trace side was.  What mods are you looking to do?  You can see a another component side pic of Rev. E here: http://diy.erikhansen.net/gcb95.htm.  Scroll to the bottom of the page.

Word of caution...be very very careful desoldering components.  These boards can have their traces/pads lifted very easily.  It happened to me.  Luckily I was able to fix it using a jumper wire.

[kevn]

vanhansen - Thanks for the link & the warning! My plan is to do the following:

- True bypass mod - as illustrated in Andreas Möllers paper
- gain increase (390 ohm)- indyguitarist
- Input resistor (68k) - volume boost - indyguitarist
- Vocal mod (33k) - indyguitarist
- midrange mod (1.5k)- indyguitarist
- sweep freq mod (.01uf) - indyguitarist

The values in parenthesis are the stock values (hopefully this is ok to include here as I'm not indicating the replacement values). I suppose I could try to figure out which components have these values and hope that I get it right, but I'd rather be more certain!

One other question. Will the pedal work properly, with truebypass, using an external voltage supply, after the true bypass mod?

Thanks again - kevin

[Hal]

do them one at a time.  That way, if you mess up, you know where the problem is.

[vanhansen]

Gotcha.  Well, like Hal said, do one at a time.  The vocal resistor is right next to the inductor behind the input jack.  Can't miss it.  I'll have to look at my board again to get where the others are.  It's been a while since I did anything with mine and it needs to be tweaked a bit more.  Andreas is a big help too and he knows more about these wahs than I do.  He helped me with mine.

True bypass will not affect it's ability to use external power at all.  In fact, I use mine with batteries anyway because it's just quieter.  Even with a regulated supply I get some power supply noise when my wah is hooked up to the chain.

[kevn]

One at a time- will do! Thanks for the the additional info. If your able to locate the other components please post! I sent Andreas an email from the link that was on the bottom of his paper. Perhaps he never received it. Does he participate here?

[kevn]

I did get a response from Andreas Moller on this and he provided the following info
(reminder, this is for the rev E board):

>- gain increase resistor (stock 390 ohm) - "The gain resistor (usually a 390ohm) is
located below Q1 (the left of the two transistors), and it is the left and
slightly lower of the two resistors found there."

>- Input resistor (stock 68k) - volume boost - "the 68K input
resistor (blue/gray/orange) is located immediately to the right of the
midrange resistor."

>- Vocal mod resistor (stock 33k) - "the 33K resistor is located in the same (somewhat
awkward) place as on the newer boards, right to the left of the inductor and
slightly covered by the input jack."

>- midrange mod resistor(stock 1.5k) - "The midrange (1.5K) resistor
is the one that is dead center right below the inductor, set slightly higher
than the others."

>- sweep freq mod cap (stock .01uf) - "The sweep cap (0.01uF) is the small blue capacitor located right above
Q2 (to the right of the 1.5K midrange resistor)"

Perhaps this will help someone else some day.............

[vanhansen]

Excellent.  I knew he'd know where everything was.  Glad he replied that fast cause I haven't had the chance to even open mine up.  When I have time I'll take this info and label the pic of my board.

Thanks for sharing this, kevn.

[kevn]

Your welcome, and thanks for your input, it was very helpful!

I'm wondering, since you have the same board as mine, if you notice a lot of noise, getting louder & higher in frequency as the pedal is pressed. I hadnt played the pedal in about 5 years, and dont remember wether it was noisy then or not. I did change the pot to a Hot Potz 2 but have made no other changes, yet. I'm wondering if the noise is inherent in the circuit, coming from a faulty cap, noisy resistors, the new pot, all of the above....

Regards - Kevin

[vanhansen]

Actually I do.  It is a pretty noisy revision.  I haven't tried to get rid of it since I don't use it very much.  Lately it's been sitting in my closet but I need to get it out again to tweek things.  It's been turned in to the Hendrix version by adding the two additional caps but something is still missing.  I think it needs an output buffer to kick the output up a notch.