As mentioned here and here,
I've been working on a plan to add sound effects and background music to the project. To this end- I'm currently redesigning the AS-2815-3x/51 soundcard with modern components; specifically, I'm replacing the TTL PROM and 4bit counter which are both getting rare / expensive with a single MAX 3000 CPLD in 44pin PLCC. The CPLD cost 1.50 is single units... where the TTL PROM and 4bit counter are in the 5-6 range. The CPLD has just enough room to replace all the logic chips and house both sound PROMs for AS-2815-32 and AS-2815-51 designs. The -51 proms can be selected via a jumper wire. "In theory" it should work with any game listed with the AS-2518 boardset.

The sound effects tie into the existing switch matrix and run off of a raspberry pi.

The card should be a drop in replacement for existing card using mostly SMT components to keep PCB costs down.

IF anyone is interested; I posted my rev-99 schematics here:
http://pinball-mods.com/blogs/wp-content/uploads/2013/09/Pi_AS-2518-50_rev0_web.pdf
Still need to take free gates and tie them up so they don't float.

Also need to renumber components now that the layout is nearly complete. Then generate SilkScreen. I put a small prototyping area under the RazPi... just incase I need to do some rework.

Hope to have the design committed to OSHPark by the weekend.