NBA Fastbreak: adding the serial port for linked play

Steps

• The WPC-95 A/V board ships without its two serial chips. Fit a MAX239 RS-232 driver at U22 and a 16C450 UART at U24 (a 16C550 works).
• Connector J607: pin 1 ground, 2 TX out, 3 RX in, 4 CTS, 5 RTS, 6 DTR, 7 DSR, 8 key, 9 RI, 10 DCD. Basic RS-232 needs only pins 1 to 3.
• With the chips fitted the system detects the port and can send audits out; printouts may need enabling in the adjustments.
• To link two games, wire them null-modem (TX and RX swapped between games).

Systems

• WPC-95

Games

• NBA Fastbreak

Related tips

• Sound cuts out or a rising shriek after a few minutes
• WPC-95 audio/visual board LED and beep codes
• DCS or WPC-95 sound faults: amps and op-amps
• Early WPC-95 games: static or thin, tinny sound
• WPC-95 won't boot with the A/V board plugged in after a -125 V short

Source: Repairing Williams/Bally WPC Pinball Games from 1990 to 1999, Part Three, Clay Harrell (pinrepair.com)