GGG DOD 250 '77 Gray Version - Not Working

[afrogoose]

Hi Everyone,

After a couple of years away from building pedals I tried building the General Guitar Gadgets DOD 250 '77 Gray Version kit.  I think I've completely lost my mojo because I can't seem to trouble shoot the reason why this pedal isn't working. 

http://www.generalguitargadgets.com/pdf/ggg_dist_g250_sc.pdf

The pedal works in bypass mode.  When it's engaged the LED lights, but there is no signal. 

I'm wondering if it has something to do with the fact that I wired the clipping diodes off-board to a three way switch? (see pic).  I have done this successfully in the past and I believe I'm doing it right.


Here are the voltages I'm getting on the IC.  Everything seems to be a bit low.

Pin 1 = 0.00v
Pin 2 = 3.86v
Pin 3 = 3.71v
Pin 4 = 0.00v
Pin 5 = 0.00v
Pin 6 = 3.90v
Pin 7 = 7.55v
Pin 8 = 0.00v

FWIW, one of the suggestions on "what to do when it doesn't work" is to check the voltage at the end of the battery lead, and in this case it's connected to the DC jack and it reads 7.5V.

Here are some pics.





If anyone has any suggestions on what part of the project I should focus my attention on that would be hugely appreciated!!!

Thank you in advance!!!!

[Elijah-Baley]

I'm building a dod250 (yellow) on veroboard, GGG version.
I can suggest you to try with an audio probe and see where the signal is stop. Could be a stupid mistake.

[UKToecutter]

Looks to me like you've put a dead short between output and ground by jumpering D2.
Just snip the link.

[afrogoose]

Oh my goodness!! UKToecutter, you sweet, sweet man!!  Thank you very much!!

I guess I figured I need to jumper that because there was the dummy jumper on D3 that came with the kit.  I'm guessing now that that dummy jumper doesn't actually make a connection?  Or else I'm not understanding why the D3 jumper doesn't short out the signal yet D2 does.

Does anyone think there is a better way of wiring up the off-board diodes?  I'm wondering if maybe I should have connected one lug of the switch to D1 and D2, and then connected those to ground...?

I'm an idiot.
 

[bluebunny]

Does anyone think there is a better way of wiring up the off-board diodes?

Given that there's no room on the board for lots of diode combinations, putting them on the switch as you've done seems like a pretty reasonable way to go.  Stick with what you've got! 

[UKToecutter]

The way you've wired the switch is good.

The anode of D1 and the cathode of D2 are connected together anyway so you only need one wire from either to one pole and Gnd to the other pole which is exactly what you've done by going across D1.

[afrogoose]

Hey!  Thanks guys.  Thanks for the speedy replies and the help!!

Ok, so it's good to know that I am on the right track as far as the 3 way switch is concerned, but I'm noticing that the pedal is distorting very much.  At full gain it's fuzzy, but not nearly as distorted as it should be.  I'm wondering if I'm only distorting one half of the waveform the way I have it wired up?  On the 3 way switch itself, I have D1 wired to the center poles, and then the outside poles have the Ge diodes and 2 LEDs in series in reverse polarity. 

If this is correct, do you guys have any other suggestions on where to look for places where I might have wired in a wrong value resistor/cap?  I triple checked everything to make sure that all the values are correct, so I'm wondering if it isn't something to do with the way the switch is wired.

Thanks again!!!

[UKToecutter]

What is that next to D2 with a single black band?
According to GGG that should be a jumper?

[afrogoose]

That's a good question.  They give you a jumper to use in the kit in case you don't want to put a diode in D3.  I'm guessing that's easier than giving an inch of buss wire in every kit.