Just to complete my earlier message in case someone comes across this in the future while troubleshooting their 746, I found the problem. IC1706 voltage comparator went bad. It is always putting out 1.3V to the Reset pin of the CPU. I believe this device is supposed to hold the cpu in reset (low) until the main power circuit comes up and then release the reset (allow it to go to +5v) once the power is on. Mine was always at 1.3V. I strapped a 1k resistor from a +5V source to the reset pin and I can now get the rig to power up. It's a temp fix since I have to first plug in 12V, then apply the 5V via the resistor. I just won't shut it off during the contest, hi.