Let’s see if we can get the MPU to boot before doing anything else. The MPU only needs the power connector so remove all connectors from the MPU board except for J4. Power up the machine and watch the LED on the MPU board closely. Refer to post #23 by mrm_4 detailing what the flashes mean. The first flicker is very quick and faint and can be missed. This first flicker is not counted as a flash.
When you see a flash that means the test passed.
Count the flashes and report back. If the same as before, only 2, then there is a problem with U8, cmos ram.
Check voltages on the MPU board as follows:
Set your dm to dc volts and connect thEblack ground lead to TP4
Red meter lead to TP5, should be close to +5 vdc8F8B11FB-F8FD-42E8-BEF2-F0FCB262EFFB (resized).jpeg
Red meter lead to TP2, should be close to +12 vdc
Red meter lead to TP3, should be close to +19 vdc but will bounce around since this is unregulated voltage. This voltage comes through a resistor from pin 15 of J4 which should be +43 vdc. This is only neede to get the final 7th flash.