Have you replaced the capacitor at C23 on Solenoid Driver board?

The filter cap hold the 5V steady on the MPU. The MPU sees things faster than your meter so if the power fluctuation that happen in milliseconds cause the MPU to lose 5V to logic and game crashes. My humble opinion.

I would only trust measuring by ESR. Besides the picture showed looks like an original on that board. It's way past its life expectancy. See vid1900 guides for rebuilding solenoid driver board.

I would also recommend you repin all connectors male and female. It eliminates random issues in the game. With issues you are having I would start with driver board J3 and MPU J4.

connectors connectors connectors... did you try Great Plains Electronics? He sells caps for the SDB and .100 pins.

I would reflow the header pins on the male side of P1 display. Most of the issues I have seen (short broken glass) with them are broken or cracked solder joints on male connectors. If the glass is not cracked broken or burned. The display can more than likely be fixed.

Lol. I get a game I unplug all the connectors in the head and on rectifier. I make sure everything is right at the transformer, then plugging things in one at a time move to the rectifier, then sdb, then MPU. This helps from accidental frying something until you know you have stable voltage. I have still fried plenty! You will make a big difference in those old displays by upgrading the resistors at R1, R3 , R5, R7, and R11 to 1/2 watt. If you have ability to desolder change the .156 male headers. The displays will burn noticeably brighter. I turn the voltage down to 180v on them. Some folks go lower but I wonder what that dose to the power demand? I just got done upgrading 10 displays and have 5 more to do.

The 7.3 volts on the rectifier is only a pass thru for the fuse. The rectifier dose nothing to this voltage. It comes off the transformer at lugs 17 and 18. Set your meter to AC and put on the transformer lugs 17 and 18, should get 7.3 vac. If you don't, more than likely you have an issue with transformer.

That's a lot on TP2. That should be turned down to 190 ish. I run mine at 180. Some folks go lower. The displays also chained together. Did you swap a different display into P2 and see if they come back on?

What voltage do you have on the SDB at J3 pin 8?

Correct. Move 4 to 2. But if the display fuse is blown....

Always check voltage before you hook anything back up. I was just saying by the ... if the fuse on the driver board is blown then you won't have displays anyway until it is replaced.

Yes, put leads on Tp2 and adjust the trimmer on the HV till voltage reads what you want to run displays.