Let me start by saying that the Emexar board is lovely and very nice to work with. I was beautiful before I started trying to remember how to solder – I did OK but you’ll notice a few places I had problems like the volume pot connection which is visible in the photo. However, everything I tested came out good.
The problem: When I switch to the effect with the back on and plugged into an amp, the volume drops to barely audible. The volume and gain controls do nothing. When I opened it up to use the probe described on your site, I got a high-pitched oscillating tone as soon I switched in the effect. I pulled the IC out of the socket (with power off) and no noise. Using the probe, I got a good signal out working backwards from the output jack all the way back to pin 6 on the IC. I get about 4 volts on pin 3 – I’m using a 9 volt AC supply and I get 9 volts at the jack.
I’m at a loss for how to proceed. Anything you can offer would be appreciated.
There are areas of concern on the board. The ones I point to in the image below may not all be bad because I cannot see them all clearly but I would inspect all of them. That said I would redo any areas the look like there are not properly soldered or perhaps hanging on by a thread. You can do this by reflowing and in the case of wires you may need to restrip and make a firm mechanical connection before applying the solder.