Is the blanking circuit problem just affecting the displays? If I remember correctly, if the blanking signal is low on system 6 the lamp strobes, the display and the first 16 solenoids will be disabled. The components you have replaced would affect the entire blanking system, not just the displays.

Have you monitored the blanking circuit with a meter while the game is booting? Both at the cpu and at the displays. Why do you think the blanking circuit is the cause of the display issue?

Blanking is supposed to be high. If it is high after the power on reset the blanking is working, at least on the MPU. It will be low before reset and high after good reset.

The blanking is probably floating on the driver board. If it floats during the power on reset delay the solenoids will all kick during reset.

Go to a 7408 in the solenoid circuits on the driver board. Logic probe on a blanking pin. Make sure the blanking is logic LOW during power on reset delay and goes logic HIGH once attract mode hits. A no reading on a blanking pin of a driver board solenoid 7408 would be floating. Usually caused by breaking a trace open when replacing the 40 pin interconnect.

Figure out if blanking is logic low during the power on reset. I suspect your blanking is fine. 90% of the time blanking is a SYMPTOM of a non working board, not a cause.

Blanking is a safety check. It monitors a display PIA line for activity. If there is no activity, blanking goes LOW to turn off all lamps, solenoids and display. When the blanking is HIGH, the solenoids, lamps, etc can work because the blanking completes an AND gate, typically via 7408, to enable solenoids etc.

Locked high blanking wouldnt stop the displays from working. It might make the display lock on scrambled stuff during reset tho.

Correct readings at Blanking TP4 is LO for about a half-second, then HI for normal operation. So it was right, then you fixed the trace, now it's stuck LO. What trace did you repair...point to point?

I agree with Terry's conclusion that if blanking were the original problem it would have disabled more than just displays.

WHen you run the andre test software, can it cycle blanking high??

Pull the driver board. DMM on diode test. Red lead on ground. Black lead probe a blanking pin. Does it read shorted????? Do the same on the MPU.

Blanking failures where it shorts to ground happen typically when a solenoid circuit fries a 7408 out or a lamp column circuit fries out the 7408 there.