Diode orientation on #44/47 lamp sockets, and 555 sockets

On a #44/47 socket with a diode, the banded end goes to the middle lug and the other end to the lug for the bulb tip. On 555 playfield sockets the small outer metal tabs get bent and stop contacting the lamp board; bend them back. On lamp boards the 1N4004s can crack if soldered tight to the board, and the Molex header joints often crack.

Systems

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

Related tips

• Why diodes on 555 lamp boards crack
• Testing a lamp diode
• Test a lamp socket diode in place
• Testing lamp-row drivers with a test lamp
• Testing lamp-column drivers with a test lamp
• Lamp diodes sit on small boards at each socket
• Test a 1N400x diode on a coil, lamp socket or switch
• Bulbs to keep on hand for WPC games

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