williams system 4 phoenix machine
so, dragging this one back from the grave and now have it up and running mostly correctly but still a nagging issue, when the power switch is turned on, all of the controlled coils fire for a split second and then the MPU boots and all is normal - none of them are stuck on. i am not that familiar with the intricacies of a system 4 machine but i don't believe this is normal behavior
i am assuming it may be a blanking issue of some sort, so monitoring the PIA at position 18 pin 4 there is pulsing activity, pin 19 on same PIA goes from nothing straight to high with no pulsing at power on
timer 556 pins 9 & 13 are both high no pulsing
i feel like i am missing the initial low signal that would prevent these coils from firing at power on
or am i?