What the SRC resistor/capacitor packs on the CPU board do
Pre-System 11B CPU boards use 10-pin SRC packs with eight resistors to +5 V (pin 1) and eight 470 pF capacitors to ground (pin 10). SRC6 (1k) feeds the switch columns; SRC2, SRC4, SRC5 (4.7k) score display data; SRC7, SRC8 display digit strobes; SRC9 display BCD; SRC1, SRC3 the sound board interface. System 11B boards replaced SRC6 with discrete parts.
Systems
Related tips
- Checking ground and +5 V on the CPU board
- Which System 11 CPU boards fit which games
- Running the CPU board on the bench
- Checking the CPU clock signal
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- What each 6821 PIA on the CPU board controls
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Source: Repairing Williams System 11 Pinball 1986 to 1990, Part Three, Clay Harrell