ok i don't get it, thinking that polarity checking a resistor doesn't matter, I wasn't paying attention before, but now if I check resistance between 5v and GND edge traces on the pcb, I get 93ohms one way and if I swap the leads I get 58ohms... so some diodes in the circuit are affecting that reading but either way it is too high right? This is pins 1&2=GND and 3&4=5v on the top side of the cpu pcb
as journeymandt pointed out above, I'm having a similar issue with my asteroids deluxe, and just now checked and have 276ohms on that pcb one way and 242ohms the other way, interesting
edit: low! not high... will look with fresh eyes tomorrow
You are reading too much into the meter measurements on the inputs to the board(both games) at this point in time.
This is for both games... if all your connections are good, and your +5v is reading good without the game pcb connected(you did wiggle the wires to discount compromised crimps at the pins right?) You want to determine if it's a pcb issue, or a power supply issue first.
Check the power supply(both machines) by loading the supply with a different load. go to the auto parts store and buy a 6v bulb and a pigtail socket.(I think I mentioned an 1158 bulb before, but I'm too lazy to look back).... setup the bulb and socket with alligator clips... a 17W bulb should draw about 3 amps(math says 3.4A at 5V with a 17W bulb). With the pcb disconnected, clip the leads from the bulb to the ground and +5v leads/wires/test points, whatever... and measure the output with your multimeter.
If the voltage sags(you don't get around 5V) then your PS is the issue.
Alternatively, if you feed the pcb with 5v from a known good supply(hot and ground to their respective places) and the voltage sags, or pops a fuse... then you know it's a pcb issue....
Pcb issue means you start by checking bypass caps for shorts, and give a side eye to tantalums... they often fail shorted which can sag a good power supply.
Also of note.... if your +/- 12V rails on a Switcher are shorted, it will cause the Switcher to shut down... which of course will drop your 5v too... in other words with a switcher, it is possible the problem can be on the +/-12v side(usually audio) and not the 5v side.
That's why I asked if you had the OG supply, or if it had been replaced with a switcher... the OG supply has a transformer that feeds 2 switching "modules"... one for +/-12V, and 1 for 5V... the OG setup shouldn't shut down the 5V side if the 12V side is shorted, but a switching supply that feeds both could.
Obviously the other game differs in that it doesn't have a switcher... but, loading the supply with the pcb disconnected will reveal to you to a board problem, or a power supply problem.
You need to determine which side of the 5V is the problem to know what to look at next
Good luck
Dylan