Troubleshooting a modded Dunlop Crybaby

[Bon]

Hi,
I've been modding my GCB-95 a little bit lately. First I added true bypass a few weeks ago and it worked great (no led yet though), and yesterday I added the rest of the mods I had prepared for it: variable Q with a 100k pot in line with the original 33k resistor (first I tried just the pot, but I didn't find values under 30k useful for me); variable sweep with a 4 position rotary switch and .022uF, .015uF, .01uF and 4.7nF pots; I also added the led this time and changed the footswitch because it wasn't very smooth.

All the mods worked for a while, few minutes, but then the wah started working as a volume pedal. The tone is a little lower. I've read somewhere that if the 4.7uF electrolitic is disconnected, the wah behaves as a volume pedal, but mine doesn't look (visually) broken, and I don't know exactly how to troubleshoot it. I get ~0'6v from pin to pin in the cap. I soldered the original sweep cap (0.01uF) and the pot is in the lowest position, reading 33.6kOhm.
I know one of the first things to do is changing the electrolitics, but it's Sunday and I can't go buy new ones 

If you may need more readings for info, I'll provide them asap.

Thanks in advance

[joegagan]

i'll skip the jovi jokes. welcome.

if you have a multimeter, do some checking  across components to traces, etc , etc. basically check that every path is intact. refer to the schem if needed. i still think the 4.7 uf is the most suspect, but much more likely it has lifted a pad or something other than the the cap actually going bad. it happens, but gcb95s are usually fairly new, unlikely a cap failure.

your modding may have stressed a wire to the breaking point, or messed with the pads or traces.

check all the above before you try a new 4.7uf

those dunlop boards are robust, very nice for modding .

[Bon]

Hi Joe, thank you for the answer.
I prefer Scott in stead of Jovi, but it's fine

I checked and re-checked all the tracks and pins, but I've found a little anomaly, exactly in the cap. The pins look like they've been heated (I provide photo, but I'm not sure if it's clear). They doesn't look like the rest of the un-modified pins, neither like re-soldered pins. The rest of the cap looks just fine


That's why I provided the cap's voltage, so someone else could give me his and compare if the cap was broken. Anyway, if tomorrow I can get some spare time I'll go buy one and see if it solves my problem.
The thing that confuses me most is that noone else had the same problem here before, as I did some research on the forum. Everyone either has a silent wah, or a non-changing sound wah. Does any other component in the circuit convert wah to volume pedal??

Now, I'd like to know how I provoked it, because as you said, new devices are not likely to have a cap failure and this one has less than a year. It must have been something I've done while modding. I suspect that hot-swapping the sweep cap is the reason, could I be right? Changing the Q didn't make any strange noise on the amp, but changing the sweep made a bump noise, just like when you unplug the guitar with the amp on.

[Bon]

Well, I solved the problem. Looks like adding cables inside the box moved the inductor when using the wah, and it's very sensitive to movement. So now I'm going to set it in the right position, glue it down and try to route the cables on it's sides so they don't move it again.
Thanks for the help anyway Joe 

[joegagan]

that is what i was referring to, something got moved with your modding. i almost typed that you should check your inductor mounting/solder joints
glad you got it sorted

[Paul Marossy]

Well, I solved the problem. Looks like adding cables inside the box moved the inductor when using the wah, and it's very sensitive to movement. So now I'm going to set it in the right position, glue it down and try to route the cables on it's sides so they don't move it again.

That's kind of scary that that can happen. Good thing one of those TINY wires on the post of the inductor didn't break.

[Bon]

yeah, I wasn't completely sure about what to do, either try to glue it or directly substitute it entirely, but since I can't find one in short time I decided to glue it and the wah behaves great now. I love the Q mod  

PS: next "mod" -> light plate. I just have to find a plastic dealer around here