Wah mod

[Bflat5]

Hi guys, first post here.

I have a Vox v847 wah that I recently did a true bypass mod on. Switched on it squeals and the sound of the wah is a bit harsh . So far the switch is the only thing changed. Any ideas what the problem could be?

[copachino]

Any image of the wiring?? Voltages on transistors

[jball85]

Yeah we need some pics man. If that's not possible, here are some links to check your wiring with.

http://www.diystompboxes.com/smfforum/index.php?topic=70502.0

http://www.fulltone.com/sites/default/files/manuals/fulltone-v847-mod.pdf

Welcome to the forum.

[Bflat5]

Sorry, I didn't have pics last night when I posted this, here's some I grabbed earlier. I wasn't able to get the voltages though. Also, I followed the wiring from a youtube video.



As you can probably tell, this is an older older.



Here's the video I followed.

[MarcFive]

Ya, that Fulltone link jball85 posted: http://www.fulltone.com/sites/default/files/manuals/fulltone-v847-mod.pdf

Would be my suggestion. That wiring you've got going on doesn't ground the board input when bypassed. But I don't know why it's whining when on. You may have gotten the switch too hot when soldering, that looks like a big glob of solder on one of those legs. In any case I'd scrap that wiring layout. It's hard to tell where the Black wire on Lug1 of your pot is going. To the output jack ring I would guess(?). It should also have a wire going to the switch from that lug for grounding like the Fulltone layout.

It might be a good idea to study a few layouts of the VOX wiring and see if someone has modded the pedal before to see if thats playing a role. I can't trace the wiring with your photo's.

[Bflat5]

I just rewired it following the fulltone mod and now there's no output switched on or off.

[MarcFive]

I just rewired it following the fulltone mod and now there's no output switched on or off.

Did you use the same switch or did you check it? A picture of what you did would help. Did you trace the wiring to see if it was modded?

[Bflat5]

Same switch, I guess I could start over with a new one. The only ones I have are the type pictured. Should I buy the kind pictured in the fulltone diagram or will the ones I have do the job?

When I started over I removed all connections then wired it again using pins 1 thru 6. Zero sound. Then I resoldered a lead to pins 7 and 9 and there was sound, but very low, weak volume.

I'm sure you can tell I'm new to pedal mod'ing so your help is greatly appreciated!!

Here's a picture of the switch,

[TGP39]

Whenever I solder up a switch, I get out my multimeter and I test for continuity between lugs 1&2, 4&5, 7&8.  Then I press the switch and test 2 things:
1. I get no continuity (unless a wire connection has been made) between the above lugs.
2. That I do get continuity between lugs 2&3, 5&6, 8&9.

It's pretty easy to get those 3pdt switches too hot by overheating the lugs. That's why I always test.  The DPDT switches you normally find in a wha are way more robust, but it will take more work to have a led on board.  The choice is really yours. You can do everything you want with those blue 3pdt switches, just be careful and test them.

Steve.

[jimilee]

Yeah, get yourself a dpdt stomp


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[Bflat5]

Thanks guys, I'll give it another go and check the switch,

Also, in the fulltone instructions there's no mention of dropping the 68k input resistor to 57k or lower, but have been told that needs to be done because of a level drop. Should this still be done with specific mod?