After a power cycle the monitor shows no picture, only a blank raster (adjusting the monitor pots turns it green or black), while the game still lights, makes sounds and can be played. The MPU and Vidiot LED flash counts are normal.

Video screen blank (raster only) but the game still plays: Vidiot video chip

Cause: A raster means the monitor itself is working; the fault was in the video output on the Vidiot board, here the U16 video chip.

Checks

• Confirm there is a raster on the monitor.
• Check the supply test points on the Vidiot board (TP5 and TP6) against the values printed on the board.
• Repin the Vidiot connectors.

Fix

• Replace the U16 video chip on the Vidiot board.

The monitor holds high voltage even when switched off; leave the monitor chassis alone unless you know how to discharge it.

Systems

• Bally MPU AS-2518-35

Games

• Baby Pac-Man

Related tips

• All score displays blank with the MPU fully booting
• A display not working from MPU or sound board faults

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