Twilight Zone: LED lighting mod for the clock

Steps

• You need four bright water-clear white 5 mm (T1-3/4) LEDs, plus four 1/2 W resistors of 100 or 133 ohm.
• Fit the resistors at D1 to D4 and the LEDs in place of the #86 lamps, bending the leads to spread light across the face.
• The supply is AC so the LEDs work either way round, but fit them so two light on each half of the AC cycle.
• LEDs cut the clock's power from about 8 W to about 1 W (internal temperature about 125 degrees F on modified original boards, versus about 160 unmodified). The light is bluer than stock.
• LEDs don't repair earlier heat damage; fix burnt traces, optos, R1-R8 and the interboard connector first.

Systems

• WPC Fliptronics

Games

• Twilight Zone

Related tips

• Twilight Zone clock uses eight sensitive U optos
• Twilight Zone: adding an adjustment pot to the trough proximity sensor
• Twilight Zone trough proximity sensor (switch 26) problems
• Twilight Zone ninth switch column (clock switches)
• Test report lists switches the game doesn't have
• Ninth switch column on Twilight Zone, Indiana Jones and STNG
• Random display lines and all flippers energising at power-on

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