a12 troubleshooting...continued.

[drunton]

Kelly,
Have you looked at nulling the voltage offset (step 6 of the last page of the assembly instructions)?

I screwed up the polarity on one of the 47uF electrolyitics, and somehow it blew the LED and ended up with nearly 8V DC on the input of the opamp pin 2. My MAP op amp got really warm. Measure the voltage at the junction of R20 and C8 and see if you can get it pretty close to 0V (with R19 exacrtly in the middle). If not, there is a problem in the offset adjust circuitry somewhere.

Maybe just an idea?
Dave