Uglyface Build - Debugging help appreciated

Started by PedalBuilder, January 18, 2009, 07:10:48 PM

Previous topic - Next topic

PedalBuilder

I just finished up the wiring of an Uglyface, my first scratch build, and it's not getting any guitar signal through.  I can use the threshold to dial in noise and the frequency knob will let me control the frequency of it (volume knob works to adjust volume of it as well), but it doesn't get the slightest bit of guitar signal.  The effect lets sound through when bypassed.  The LED lights up when the effect is activated (orange super bright with 4.7k resistor).  I have my switch wired up with grounded input as shown here:

http://www.generalguitargadgets.com/diagrams/switch_lo_3pdt_ig_dcjack.gif

Except I do not have a battery clip - I wired the positive of the DC jack to the board 9V+ and the negative to the ring of the input.  I used the perfboard layout found here: http://www.home-wrecker.com/uglyface.html

I did not make my own vactrol, I bought the one listed.  I substituted one 4.7 uF electro cap for 2.2 uF in the middle of the layout.  I used the 250K frequency pot discussed there as well as the .001 caps.  So the 4.7 uF cap and buying a vactrol were the only places I deviated from what is listed.  I checked my perf traces and they all look good.  I checked with the multimeter and there are a bunch of spots with no voltage.  Here's the info:

9v+ is getting 9.02
Vactrol isn't getting anything on any pin.

IC1 - LM386
1 - 1.38
2 - 0
3 - 0
4 - 0
5 - 5.21
6 - 9.01
7 - 4.51
8 - 1.38

IC2 - 555
1 - 0
2 - 0
3 - 0
4 - 1.03
5 - 5.77
6 - 0
7 - 0
8 - 9.02

I took the layout on that site and flipped it horizontally, and then darkened the traces.  This would allow me to check the bottom of my perf to make sure I didn't miss anything.  I've been over it 3 times and don't see anything.  I added voltage at a few points on the picture as well, including the ICs info mentioned above:

http://s68.photobucket.com/albums/i13/thestevil/Uglyface/?action=view&current=UglyfaceTroubleshooting.jpg

If someone could let me know where voltage is getting cut off or where I should test next, that would be great.  I don't know what it should be or enough about this yet to figure it out.  I'm hoping it's just something stupid.  I do not yet have an audio probe, but I am guessing that with all of the zeros in the voltage, I won't need one for this particular bug.  Thanks in advance,

Steve

PedalBuilder

I just made an audio probe since this is really bugging me.  I get clean signal from the guitar where it's soldered in and goes to pin 3 of the 386.  I checked pin 5 (I think that's where I should go next, per a pinout I found) and I get loud distorty guitar noise from pin 5 all the way around that bend to where it goes to the cap - from there it goes through an above-board jumper to another cap (measured from one end of the jumper to the other for continuity and it's good) and also down to the sensitivity pot.  I can't get any guitar noises as either of those places. 

I just checked continuity above/below the board and it looks like someone screwed up soldering...apparently a good looking solder joint only helps things out if you push the cap down through far enough to be in it.  I'm cleaning things up and I'll report back tomorrow...hold off on anything in the meantime...sorry...

PedalBuilder

 :-\

So apparently not soldering in part of that cap is a pretty big mistake in the Uglyface circuit.  Who knew?  The audio probe is super cool and not even knowing much about the circuit, it led me to the mistake.  That's pretty intense.  The pedal now works and sounds even better than I had imagined.  If you roll back the volume on the guitar, you can get some industrial sounding fuzzed notes with quick decay.  They just come through as you pick and fizzle out shortly after.  It's probably the best pedal ever for turning your brain off and playing with a scale...and I'm sure would come in handy when you need a weird noise somewhere.  Enough ranting...thanks and sorry for the newbie mistake post.

Steve

snarblinge

I'm having an issue with mine where the led isn't getting any voltage past the 100uf cap (c3 which replaces the 2.2uf in the lfo mod) no issues with signal getting though. if I jumper accross it it lights up great and seems to be ok, waiting to get it back into the box to be sure. any ideas.
b.

snarblinge.tumblr.com