Leon's older memory test read with a tester LED
With older Leon versions, clip the tester LED from +5 V to CPU IC1 pin 15 (not a logic probe) and press SW1. LED steady: IC13 bad. One flash then on: IC19 (5101) bad. Two flashes then on: IC16 bad. Two flashes then normal blinking: all RAM good. Any other pattern usually means IC19.
Systems
Related tips
- A PIA output fails Leon's test but the PIA is good
- Leon's test EPROM fitted but the LEDs do not start flashing
- Leon code running but LEDs dark: bad CPU PIA IC18
- Reading the software ID in audit 00
- Memory protect chips to check after the 5101
- Leon's test EPROM: what to burn and where it goes
- Running Leon's test EPROM with the boards still in the game
- Add two test LEDs to a System 7 CPU board
Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part Two, Clay Harrell (pinrepair.com)