WPC DMD shows garbage and a RAM address error: reseat the ribbon cables first

If the dot matrix shows extra lines or garbage that comes and goes, and display test reports a RAM address error, reseat all the ribbon cables to the DMD controller and the display before replacing the controller's RAM. A cable can also be tested by fitting it reversed at both ends; if the fault changes, replace the cable. If reseating doesn't help, the controller RAM is the next suspect.

Systems

• WPC Dot Matrix
• WPC Fliptronics
• WPC DCS

Related tips

• DMD fully lit with no picture while the game plays: bad DMD panel
• Blank display, garbage or diagonal lines: reseat ribbon cables
• WPC display and DMD controller board versions
• DMD dead though display and controller work in other games: CPU board fault
• LCD/LED replacement display garbled after the game was shipped: reseat the cables
• Moving vertical bars across the DMD with known-good display parts: CPU board fault
• Wavy hum bar, bounce or roll on the display
• Display shows garbage or nothing though the glass is fine

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