Test regulator on back board. A good regulator will measure around 350 ohms. Regulator
is dead short on MPU backboard (this is shorting the 12v to ground). Why didn't PSU
7.5 amp fuse blow immediately?
Board is badly battery damaged.
Start with the obvious, replace C19 (103z) and clean up battery residue. Clean back
mask and buzz out all the tracks around the battery area.
IC19 is a worry because it is so badly corroded.
Battery vapour has got as far as IC3 and IC8, clean corrosion off pins. IC33 and
IC34 are also corroded, clean pins. C13 falls apart, so replace (1000pF)
Amazingly all tracks are good.
Ready to power on with known good regulator back board.
Boots OK into attract. Slight buzz from one triac, but that will sort itself.
All lamps OK, Reel spin OK, Coins OK, Switches OK, Sound OK.
Slide test OK. Needs to soak for a few hours, but I think we have a winner.