Thanks Luke for replying.
The short history; bought this machine doa. Board does not boot, in or out of machine.
I have the board out. using 5 volt PC power supply to bench test. The board is a newer style board with the space for a 28 pin 6264 memory. It will not boot. . When I got the board, the jumper 4 had been moved to jumper 3 to accommodate the 6116 memory, but the zero ohm resistor had been replaced with a piece of wire.
The 24 pin memory had been placed at the bottom of the 28 pin socket. The closest I get to booting is when I have the original 24 pin 6116 memory installed at the top of the 28 pin socket (with memory installed in proper direction) the red light blinks for a few seconds and the goes solid red. (All I get is solid red light with the new 6264 memory I have with jumper 4 in place)
I noticed the u6 DS1210 was dropping 1 volt on the output to the memory ( which drops down below 2 volts) . the DS1210 data sheet says that I should only see at most a .3 volt drop.
When I socketed and replaced the expensive ds1210 chip, it worked properly for just a short while. Then when I rechecked the chip, it was down to 1 volt drop, like the previous bad chip.
That being said, the manual says they use a ZERO ohm resistor. Jumper 1 has a ZERO ohm resistor for the 27512 EPROM. The memory jumper does not have a resistor jumper. Just a wire.
Can that be my booting problem, or just another thing that needs to be fixed first? Or something that should have no effect at all.