I've got a wide body Williams Contact pinball project that I just set up to work on. It's been in storage for quite some time and is in unknown condition.
Time to inspect the boards first.
It has a system 4 board in it (1D-2001-133-4). This was originally a system 3 game. The original game/flipper roms were still in the game and a couple of them had broken legs. The original scanbe sockets were still present. Obviously, it's not going to work like that.
Time for an upgrade.
I purchased a set of new game/flipper roms which only use IC14, IC17, and IC20. Of course this is the perfect time to go through the boards as well. All connector pins were cleaned and re-flowed. The scanbe sockets were removed and new sockets were installed for the game/flipper roms at IC14, IC17, and IC20. The CPU at IC1 and the clock at IC5 were also in scanbe scokets so those were removed and replaced with new sockets as well.
My main question is this:
Are there modifications that need to be done to the system 4 board to run a system 3 game (Contact in this case)? System 4 already has the IC14 socket to accommodate the new set of roms, but does anything need to be modified, or is this a plug and play adventure?
I understand there are some small modifications to be done on a system 3 board that you are using the updated roms for (add the missing IC 14 socket and converting the selection circuit). But this is a system 4 mpu that already had a socket at IC14. I'm guessing you don't need to do the selection circuit modification, but could be wrong.
I'm thinking this should be plug and play, unless the mpu has issues of its own. Just wanted to make sure first.