A half-working UDN7180 can still be used
System 3 to 6 master display boards use only half of the UDN7180 at IC4 (the even pins 2-8 and odd pins 11-17 can be bent out of the socket and the displays still work), so a partly failed 7180 may still serve in that position.
Systems
Related tips
- Missing segments: check the UDN7180 with a probe
- Four digits missing on the player 2 and 3 displays: bad driver IC12 on the master display
- Bottom segments missing and master display resistors burning: shorted display glass
- Master display board versions
- All score displays dead
- One score display dead
- UDN display driver chips
- Diode-test UDN chips and score glasses for shorts
Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part Three, Clay Harrell (pinrepair.com)