The same digit positions (for example the hundreds digit, and the first and last digits) show scrambled or stuck-on segments on the player 1 and player 3 displays, in attract mode and in play.

Same digit wrong on the player 1 and 3 displays: failed Z17 on the MPU

Cause: A failed inverter chip at Z17 on the MPU, which drives the digit strobes shared by those displays; one gate was holding a digit on.

Checks

• Swap displays between positions: if the fault stays with the position, the displays are fine.
• Repin the digit strobe connector at the MPU (A1J3), although here it did not help.
• With a logic probe in attract mode, check the Z17 gates that drive the affected digits pulse high and low.

Fix

• Replace Z17 on the MPU.

System 80 displays run on high voltage; power off before unplugging display connectors.

Systems

• Gottlieb System 80A

Games

• Jacks to Open

Related tips

• Gottlieb System 1 and System 80 power harnesses look alike: check before fitting
• Locks up when a second game is started: bad 5101 RAM
• Gottlieb System 80A: constant resets and digit 16 missing: shorted 7404 at Z26

Source: Pinball Repair help group!! (Facebook group)