After fitting new general illumination sockets, none of the GI bulbs (LED or incandescent) light, even though the GI voltage is present at the wires. Jumping the socket's metal barrel to the lug the wire is on makes the bulb light.

New GI sockets stay dark despite 6-7 VAC: GI wire soldered to the isolated diode lug

Cause: The replacement sockets are the type made for computer-controlled lamps: one lug is isolated and is only a mounting point for a diode. The GI wire was soldered to that isolated lug, so it never reached the bulb's shell.

Checks

• With a meter, check continuity from each socket lug to the bulb's centre contact and to the metal barrel.
• Compare the new socket with an original GI socket to see which tab feeds the shell.

Fix

• Move the GI wire from the isolated lug to the tab that connects to the socket's metal barrel (or the mounting tab), so one GI wire feeds the centre contact and the other the shell.
• Alternatively use the correct GI-style sockets.

Systems

• WPC Fliptronics

Games

• Creature from the Black Lagoon

Related tips

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• A few unrelated lamps never light

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