Lamp matrix fuse F114 (F106 on WPC-95) keeps blowing

Steps

• Turn off and unplug the lamp matrix connectors: J133-J138 on WPC-S and earlier, J121-J126 on WPC-95.
• Fit a new fuse and power on. If it blows now, suspect BR1 (D11-D14 on WPC-95).
• If it holds, plug the connectors back one by one; when the fuse goes, the fault is on the last one connected.
• Trace that connector's wiring for a shorted lamp socket, or a new bulb that is shorted.

Systems

• WPC Alpha-Numeric
• WPC Dot Matrix
• WPC Fliptronics
• WPC DCS
• WPC-Security (WPC-S)
• WPC-95

Related tips

• How the WPC lamp matrix works
• How the WPC lamp matrix is switched
• WPC lamp matrix and GI driver parts
• BR1 (D11-D14 on WPC-95) and the board around it scorched
• The three WPC lamp circuits
• How the lamp matrix drives a bulb
• No lamp matrix lamps light
• All matrix lamps stay on

Source: Repairing Williams/Bally WPC Pinball Games from 1990 to 1999, Part Two, Clay Harrell (pinrepair.com)