Leon test: type 2 sound board RAM IC11

Steps

• With the Leon test running and PIA outputs good, press SW1 to start the 6810 RAM test (type 2 boards only).
• LED blinking again: RAM passed. LED stays dim: test keeps looping on a fault.
• While it loops, IC11 should read: pins 1, 14, 15 at 0 V; 2-9, 13, 20-23 about 2 V; 10 and 24 at 5 V; 11, 12, 16 about 3 V; 17 and 19 about 0.5 V.
• Trace any pin that differs; usually the readings are fine and the 6810 itself has failed.

Systems

• Williams System 6 / 6A
• Williams System 7

Related tips

• Type 1 and type 2 sound boards and their switches
• Using a 6802 on a type 2 sound board
• Sound EPROMs work in either sound board type
• Check the -51/-56 PIA, RAM and amplifier with the test EPROM running
• One flash only: U7 6810 RAM
• CPU chip types: 6800 on System 3/4, 6802 or 6808 on System 6/7
• Seven flashes, then it starts over endlessly
• Which sound board each game uses

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