WPC

The Machine This Bally Twilight Zone (1993) came to me from Oklahoma City, where it had spent over two decades sitting in an outdoor shop. Years of red dust and grime had worked their way into every corner of the machine, and it needed serious attention before it could play again. Note the Oklahoma tax stamp from 1998 on the apron, and the owner said the game has essentially been kept in storage at his shop since. All the boards inside were numbers-matching original and had no work done prior which is pretty astonishing. ...

The Board This WPC-89 MPU came out of a Judge Dredd. The game had stopped booting entirely and was showing intermittent direct switch issues before it gave up — two classic symptoms that point straight to MPU corrosion damage. Diagnosis On WPC-89 MPUs, battery corrosion is one of the most common failure points. The onboard batteries leak if not replaced often, and the corrosion spreads across the board under the batteries, taking out the switch matrix components and traces underneath. In this case the corrosion had only reached U16, one of the LM339 comparator ICs responsible for the direct switch inputs, which explained the switch issues prior to the full boot failure. ...

The Machine This Williams High Speed 2: The Getaway (1992) came in with two issues — strings of GI lighting were dead or dim, and the game would occasionally refuse to boot. Both turned out to be related to the same issue — bad IDC connectors. The Problem The factory IDC (Insulation Displacement Connector) headers used on WPC games are notorious for failure over time where high current is involved, usually the GI strings and input power to the driver board. As they age, contacts loosen, get pitting or corrosion in the plating, the connection resistance increases, which generates heat. The heat degrades the connector further, which generates more heat — a cycle that eventually ends with a melted, burned connector and dead GI strings or boot/reset problems. ...