Vox V847 Modifying Fail Help Please

[Reli-Teli]

I decided to modify the bejesus out of this pedal and made the biggest mistake one can make while modding...I did all the mods at once instead of mod, test, mod, test etc...It barely makes any sound when engaged and there's no range just a wahwoh sorta of ground buzz and a static click noise in bypass when you hit the strings. I'm definitely a noob I've only been tinkering for a year and in that time successfully built a Fuzz Face Clone, modified a Crybaby and repaired two or three pedals. I'm stumped I've been over this thing over and over. I tried a few trouble shooting techniques but as far as diagnosing I fall extremely short. I spent too much time being banished to the hall in Science class. I originally had adjustable mods with pots in place. I thought maybe that was the issue so I replaced all of them with resistors. I thought maybe it was the way I installed the Whipple so I put the original inductor back in...nope. I thought maybe it was the bypass switch so I tried a brand new one, and even went so far as to wire it back to the original bypass and back again. I've spent waaaaay to much time on this thing and can't afford to spend too much more time on it in order to keep the peace on the home front. I hope it's something obvious if not it's going on eBay as is. Thanks in advance guys.

Mods performed

Mid Range
Q mod
Gain/Bass
Gain/Treble
Sweep Mod
Whipple Inductor

[PRR]

http://www.diystompboxes.com/wiki/index.php?title=Debugging

Schematics, stock and mod

Voltages (so we know if transistors are happy).

Your soldering skill? I see some doubtful joints but can't be sure.

[Reli-Teli]

Cool, thanks for the quick reply. I'll be sure to look into it tonight when I get home.

[joegagan]

those boards are pretty robust, but with all the in and out / reheating the pads, you have lifted a pad somewhere, or overheated the tiny leads inside the inductor causing a disconnect. your symptoms indicate a possible fail @ inductor  and /or the 4.7 u to gd.

don't forget to do a part by part continuity test of every connection.

use a freshly printed  or drawn schematic and a red pen to put a check mark at each correct connect, start at input and work your way all the way through.
while the meter leads are roaming around, double triple check that you haven't accidentally connected to somewhere you should not have.

i see a lot of non-stock looking resistors. are you 100% sure you have all correct values?

how do i know these things? umm ummm i have done all of them?

[Reli-Teli]

Thanks, I'll try a couple things tonight but if I don't get it then off to eBay it goes. I spent too much time on this already...lesson learned.

[Reli-Teli]

It's Alive!!!!!!I flipped the sweep cap around and Whickitty Whocketty Waaaaaah!

[joegagan]

well, polarity does not matter on the sweep cap, so i would say you had a lifted pad or cold solder that got redone when you flipped it around?

[joegagan]

anyway, good to hear.

[Reli-Teli]

 :icon_confused:Bizarre, oh well. Now all that's left to do is adjust the pot the treble has a bit of a shrill to it. I hope to take care of it with a little pot adjust if not then back to the soldering board.

[joegagan]

if you like the tone overall but would like to kill the shrill, take a cue from dunlop and others. a 330pf -1000pf to ground right at output can be handy.