High voltage is only half the equation with these displays. You need the presence of high voltage to illuminate the displays. If you have the correct high voltage on the glass displays, then you need to troubleshoot the logic circuits that "tell" the displays to turn on digits. More than half the time faulty cables are at fault.

That voltage does seem a low. The question is how low can you go and still have the displays operate? I don't have one of these games to refer to. There are display saver mod boards and a zener diode modification that are usually set to drop the supply to 91VDC. Have you ever tested any of these displays in another game to prove they actually work and are not outgassed?

The full voltage swing is 200v stock, and 180v with the zener mod to 91v. They didn't go directly to the 180 like Bally/Stern did because it's apparently harder to build that type of supply vs. the positive/negative - WMS displays just aren't referenced to ground.

Plasma displays can work with as low as 175v or so, and maybe down to 160. I run my bally/stern displays with the factory recommended 190v and they're fine.

Unfortunately, there is no easy way to test outside of a game, and you'd probably spend more money and time building a jig than buying new LED displays.

You really need a known reference to determine the fault: known good displays to plug into the game, or a known good game to plug the displays into, so you could determine which is at fault.

Most displays will have a small glow or slightly illuminated spot when they are getting high voltage, and it is sometimes difficult to see that. It's also not a definite indication that the display is functional.

Not sure if this is you're issue. But when I remove the segment cable, J7, from the master display, I end up with the same results, blank displays. It was also very tough for me to tell if any light was being generated from them at this point as well.

J7 connects to 1J3 on the cpu. Bad connection somewhere?

Schematics show that the blanking signal also travels through these connectors. I assume that signal would also be needed to light the displays?

They also work in system 7 and early 11s.

Is the MPU booting?