General Guitar Gadgets - Guv'Nor build troubleshooting

[nowhereman07]

Hey there everyone,

New member here. Name's Chuck Hayden, first time builder, long-time player. As far as electronics knowledge goes, I'd definitely say I'm on the lower end of the scale.. Been interested in electronics my whole life, but never really took the time to learn. I probably know a little more than the average kid my age (22 next Friday), and building this GGG Guv'Nor has certainly been a good toe in the water for me. I'm a total tone freak, and I hope to frequent this board from now on as I delve into more of these DIY stompbox projects. Unfortunately though, I've run into a bit of a snag with this one.

Here's the project in question: http://www.generalguitargadgets.com/index.php/projects/17-distortion/99-guvnor?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a

I haven't made any modifications to the circuit, I followed the layout carefully and along with my father (who is a long-time electrician, but no real background in audio equipment) have quadruple checked that the wiring is correct, the right parts are in the right place, and nothing is grounding-out. The pedal is negative-ground, by the way. That being said, the pedal passes signal in the bypassed position, but only slight noise while engaged and with the back cover off. I can, however, hear the tone controls, gain and volume knobs affect the noise output. I can list all the voltages tomorrow after work, but everything appears to check out except that Pins 1 and 2 on the IC are reading no voltage. The others read fine; a little low here and there, as the battery isn't quite new, but nothing outside of .5 volts. My dad seems to think that the problem is with the IC.

Sorry if I haven't provided enough info; again, I'm pretty new at this ha I will get the voltages posted tomorrow. Thanks for any initial opinions you can give me, and again, it's nice to make your acquaintance!

-Chuck

[Mike Burgundy]

Welcome!
Pins 1 and 2 should be at Vref (4.5V). The opamp wants a dual supply (so +xV and -xV referenced to ground) and we fake it into believing it has that by using a voltage devider creating a voltage midway. With a 9V battery that's 4.5V. This is fed to the +inputs (often through a resistor)  and the opamp then lifts the output to 4.5V pulling the feedback network and the - input with it. The coupling caps between stages (C3 and 5 for instance) isolate this DC level from other bits of the circuit that you don't want DC on (such as pots).
If only 1 and 2 are at ground, there's either a DC short to ground from the feedback path (there should be no DC conduction to ground there) or the opamp might be shot.
Did you use a socket? It's a great help to use sockets when youre starting out. Put one in, and swap opamps easily.
Also, since you mention voltages you've probably read the "what if it doesn't work" stickies, but I'll mention that anyway.