With LED bulbs and a replacement lamp driver board, some controlled lamps flicker and others stay dark, although the GI works.

Controlled lamps flicker or stay out after fitting a replacement lamp driver with LEDs

Cause: The replacement lamp driver has a lug that must be wired to the controlled-lamp common test point (TP13), and this game also has an auxiliary lamp driver board that drives some of the lamps and is not LED-friendly in its original form.

Checks

• Read the notes printed on the replacement lamp driver and check that its lug is wired to TP13.
• Note which lamps are still out and check in the manual whether they are driven by the auxiliary lamp board.
• Check the lamp connectors and sockets for worn pins.

Fix

• Run a wire from the lamp driver's lug to TP13 (controlled lamps common).
• For lamps on the auxiliary lamp board, fit an LED-compatible replacement auxiliary board or an LED adapter, and repin tired connectors.

Systems

• Bally MPU AS-2518-35

Games

• Cybernaut

Related tips

• LEDs flicker in controlled lamps on Bally and Stern SCR lamp boards
• Two inserts faintly lit all the time: failed lamp driver SCR
• One controlled lamp does not light
• One controlled lamp dead even after a new SCR: lamp driver board fault
• AS-2518-14 vs AS-2518-23 lamp driver boards
• Lamps on the auxiliary lamp driver board do not work
• Substitute SCRs for the lamp driver board
• One drop target lamp won't light after board work: broken wire in the harness

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