Check the voltages at the 4 corners of any of the RAM chips. The voltages should be +5VDC, +12VDC, -5VDC and ground. These voltages should be +/- 0.2V and should be stable (not varying more than 0.1V due to AC ripple).
Check the voltages at the 4 corners of any of the RAM chips. The voltages should be +5VDC, +12VDC, -5VDC and ground. These voltages should be +/- 0.2V and should be stable (not varying more than 0.1V due to AC ripple).
Thanks yellowdog i think the cpu board is too far gone and i will get a replacement,picture 30 years of operator hacks and repairs in australia on this board It has come out of an original cabinet,the ribbon cables dont even have connectors they are hardwired on.