I Need Help Trouble Shooting A Wah Pedal Footswitch?

[Guit-it-4U]

\I have a Dunlop GCB-95 Revision E model which has a brown circuit board with the jacks mounted to it,( I believe an early circuit board mounted jack model).

(1) I do not get a wah signal and everything is quiet when I engage the switch by foot or manually. I get a normal signal when switched back.


(2) I am getting 9 volts to the wire harness from the battery.


(3) My multimeter is set to 200 ohms.


(4) The single green wire on one side of the switch shows continuity to the diagonal purple wire on the other side of the switch.


(5) When the switch is activated the blue wire next to the purple wire show continuity and the green does not show continuity to either the purple or blue wire.


(6) Do I need to have a jack plugged in to the input and output to test this?


Where do I go from here?
Any suggestions or help would greatly be appreciated.




Thank You

[crentist]

I would guess you need a jack
pluged into the input side to test it.

[Kyle B]

Unlikely an electronic component such as a transistor has failed, that doesn't happen often. Usually it's a "mechanical" thing. It's very common for PCB mounted jacks and soldered-down wires to peel away from the PCB although they still look 'connected'. First thing you should do is try the chopstick method. By this, I mean plug it all in, turn it on, and poke at everything with a wooden stick to see if you can jiggle something and make it work. If you find a spot, you just need to resolder whatever you poked. Failing that, I'd suggest you just try reflowing the solder on every component, and you might get lucky. There aren't many, won't take you long.

If that all fails, or you don't wanna mess with it, bring it to me and drop it off for a few days. Happy to fix it for ya. I repair pretty much any pedal $20 http://buffalo.craigslist.org/msg/4268279254.html

[Guit-it-4U]

So Kyle,

From what I described about the switch, does the switch seem to be functional?

[Kyle B]

Per your test, the switch itself is probably OK. It sounds like the expected action from a SPDT switch (single pole double throw).

[Kyle B]

Follow up - I opened my own Crybaby, the switch works exactly as you describe - colors match your description.

[Guit-it-4U]

I have a second Crybaby which is also a Rev.E, but has a green circuit board with the components spaced more evenly. I am going to try to jump the wire harness from one another and vise versa and see what I come up with.

[Guit-it-4U]

No luck getting it to work by jumping the pin connector from another wah and vise versa. I guess I'll start by resoldering the three switch wires and then the pot wires. Can a poteniometer be just non funcitonal and cause the wah to have no sound?

[Kyle B]

Yes - but they rarely would fail like that. First they'd get all scratchy - you'd have probably replaced it long ago if it were getting that scratchy.

But you can check the pot with your multimeter. Set the meter on resistance, and if it's not auto-ranging then pick the first range over 100k (most meters would have a range setting of "200k").

Do the test with nothing plugged in. You do NOT need to desolder anything -- Often it's not possible to measure resistance in-circuit, but in this one unique circuit, it can be done. It shouldn't matter whether the switch is 'on' or 'off', but test both ways anyhow and record the results.

You should measure 100k (approximately) across the left & right pins of the pot. You can then measure between the middle & either outer pin while you rotate it (doesn't matter which one). As you slowly turn the pot, the reading should smoothly change from 0 to 100k (or 100k to 0, depending on which direction you're turning)

If you find open circuit across any two pot pins (infinte ohms), the pot is bad.