# face melter



## Mooogden (Apr 13, 2020)

I just wrapped up a build of the face melter pedal.  all of the controls work and it sounds great, but the indicator led isn't lighting up.  I made sure that the positive and negative legs were connected in the right places. and then checked with the DMM.  DMM shows that there is no voltage across the led solder points on the PCB. this leads me to believe that there could be a problem with the circuit board and not with the led.  

if anyone has any ideas as to what could be causing this please let me know, thanks.


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## GenoBluzGtr (Apr 13, 2020)

When you say "made sure the + and - legs were connected in the right places", how did you verify?  This bit me a week or so ago, and I am seeing others with the same issue.  The way they're depicted in the drawing on the off-board wiring page is not always correct, and you can't assume the square pad is +.  ONLY go by the "A" and "K" markings for Anode and Cathode respectively.   If you did this, I apologize, but if ALL else works as it should, and the only issue is the LED, this is the most likely cause.


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## music6000 (Apr 13, 2020)

Mooogden said:


> I just wrapped up a build of the face melter pedal.  all of the controls work and it sounds great, but the indicator led isn't lighting up.  I made sure that the positive and negative legs were connected in the right places. and then checked with the DMM.  DMM shows that there is no voltage across the led solder points on the PCB. this leads me to believe that there could be a problem with the circuit board and not with the led.
> 
> if anyone has any ideas as to what could be causing this please let me know, thanks.



If the Flat on the Led is not on the side of *K* it is in the wrong way


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## Mooogden (Apr 14, 2020)

i tried switching the direction of the led and now it lights up whether the pedal is on or off.  i also have the new issue of not getting any signal if the pedal is engaged.  I'm going to try and pull the pcb to see if anything has blown.


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## Mooogden (Apr 14, 2020)

I’ve solved any possible grounding problems and verified that there are no blown components. I have been facing some problems with my wires being too thin, (too high of a gauge) so I’ll replace those with thicker wires. And I noticed that it calls for a 4M7 resister between the input and vref. When I made it I only had a 3M8 and that could be causing a grounding issue similar to a post about the son of Ben pedal in this forum. I’ll replace that with the correct value and see if that has any effect.


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## Mooogden (Apr 14, 2020)

I redid all of the off board wiring and changed the value of that resistor after that it worked for roughly 30 seconds before quitting again. When I get a chance I’ll remove the pots and clean the back of the board with some iso. I removed the pcb from the enclosure and it still wasnt working. So that rules out any shorts to the enclosure.  I may have to let this one sit for a while and build some simpler circuits and then come back to it later.


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## Chuck D. Bones (Apr 15, 2020)

Putting the LED in backwards will keep it from lighting up, but won't cause the voltage drop across the LED to be zero.  The LED circuit is pretty damned simple.  Possible causes of no voltage across the LED:

R100 missing, broken or bad solder joint.
Short across LED pads on the board.
Stomp switch not wired correctly.
Bad stomp switch.
Broken trace.
That's as much as I can help without some pictures.


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## JoeRimi (Jun 17, 2020)

I am putting together a face melter. I only have 5mm red led's does that matter? will  it make a difference? and if I decide to bypass the box on off led, how would I go about doing that? Do I need to put a jumper, or just leave it alon and also what do I do about a resistor that may be there for that led? Mine is laid out differently than the hole pattern suggests also...


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## Chuck D. Bones (Jun 17, 2020)

If you want to bypass (omit?) the on/off LED, just leave it out.  No jumper.  You could also omit R100 if you want to save one part.

You can use any size LEDs you like, as long as they fit inside the box!  You can use any color you like too.  Red for the most compression, green for more balls.  
FYI, I have found that super-bright red LEDs have a higher Vf than standard red LEDs.


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## JoeRimi (Jun 17, 2020)

Thank you!


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