I'm troubleshooting a CGS85. I was going through the calibration procedure and the first two channels worked fine. I was using an input of 4.2V and was able to calibrate the outputs to match the inputs.
When I got to the third (the bottom on the wiring diagram - furthest from the power connector) the output voltage could not be raised above 1.2V. Even more strangely is that when I measure the input voltage when the 1/4" jack is inserted in the input socket, the voltage drops to .38 Volts.
It's like there's something in that section of the circuit causing a problem with the actual input signal. All the other channels work fine. I'm comparing the module to a working CGS85 built earlier and all of its inputs match its outputs.
I've re-flowed the solder. No connections look bad and I can't find any obvious bridge solders or wiring faults.
Any suggestions would be greatly appreciated!