Leon sound board test EPROM

Steps

• Burn the test ROM into a 2716 and fit it in the single EPROM socket (IC2, or IC12 on System 6/7). Early System 3/4 boards must be jumpered for a 2716.
• Power the board. With a tester LED on +5 V, CPU pin 15 (IC1, or IC9 on type 2) should blink about once a second.
• On the PIA (IC3, or IC10 on type 2), pins 2-17 should alternate each second, data pins 26-33 pulse (logic probe), reset pin 34 high.
• If a PIA output is stuck, lift that pin or cut its trace: if it now toggles, a chip it feeds is shorting it (IC6, IC8, IC9 on type 1; IC13, IC5, IC6 on type 2). Otherwise the PIA is bad.
• Refit the game ROM and press the test switch to confirm.

Systems

• Williams System 3
• Williams System 4
• Williams System 6 / 6A
• Williams System 7

Related tips

• System 3/4 sound board jumpers for 7641 PROM vs 2716
• Garbled or partial sounds from bad ROMs or sockets
• Leon's test EPROM: what to burn and where it goes
• Sound EPROMs work in either sound board type
• Flipper ROMs at IC17 and IC20: replace the originals with new EPROMs
• Convert a System 3 CPU board to a single 2716 game EPROM at IC14
• Which sound board each game uses
• Sound board jumpers for 2K sound-only games

Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part Three, Clay Harrell (pinrepair.com)