I have Flash using a system 6A CPU board, Green ROMs. The game boots fine time after time. The game plays fine with no playfield problems. Controlled lamps and solenoids all working.

I have no displays. I do have good power, +100, -97 and +5V to the master display and other displays. I have signal on all of the inputs to the displays.

I do not have +5V blanking -- blanking is 0V at the CPU. The dual timer chip has been replaced and continuity on all pins checked. I didn't think the board would boot with 0 blanking. Do I have my blanking figured wrong logically?

Replaced IC18 PIA
Replaced IC1 CPU w/68B02
Replaced IC7 7404
Replaced C31 1uF Tant Cap
Replaced Q5 2N4403
Replaced IC23 dual timer 556 TTL not CMOS version

The timer chip runs very hot -- can only hold your finger on for 5 seconds.

Board booted on the bench with driver attached:

IC18 pin 4 PIA = H/L pulsing
IC7 pin 5 and 6 = H/L pulsing

IC23 Timer
Pin 8 = H pulse only
Pin 9 = 0 blanking
pin 10 = H solid reset
pin 11 = H solid reset
pin 12 = L pulse only
pin 13 = 0 blanking
pin 14 = 5V
pin 7 = ground

I lifted pin 9 on the timer and blanking goes high. So it seems the driver board is the problem. Lots of 7408's to choose from.

With Leon's test chip, the blanking goes high/low as expected.

The root cause was IC4, 7408 on the driver board. I used grumpy's idea without the laser temp measuring device. I just used my finger to find the warmer than others on the driver board. The timer chip was running so hot as to destroy the chip ID info. The 7408 was not as hot, but was getting hot.

I replaced IC4 and blanking then when high when the boards were booted.

Problem resolved.

zacaj:
With the timer chip, pin 9 isolated from the circuit board, I found the timer was operating correctly as pin 9 would go high. Only pin 9 was pulled out of the socket so the timer was fully operating. When pin 9 was connected to the interboard connector, the driver board pulled the timer blanking signal that was high to 0V, holding the correct high timer output low as IC4 the 7408 was shorting the blanking signal to ground making it appear the timer was at fault.

The caused the 556 timer chip to heat up. The faulty 7408 that was shorting the blanking to ground also heated up making it relatively easy to find the bad 7408 of the many on the driver board. I got lucky.

Forgot to add, Thanks to Andrew, Grumpy and others for their inputs and comments.

Truly not scientific, but it was effective

I loaded the boards into the machine and the displays now are working.