Indianapolis 500 lighted target: replacing its U opto

The lighted target on Indianapolis 500 uses a four-leg U opto of the same style as the old Radio Shack 276-142 U opto. Its board has no orientation dot: the dot on that opto goes to the A terminal, where the original Williams opto had its dot on C. Confirm with a meter: red lead on A and black on K reads about 1, every other combination reads 0. If no such opto is available, drill out the rivets to remove the original case and transplant the internals pried out of a four-leg Twilight Zone style opto; the cover does not need to go back on.

Systems

• WPC-Security (WPC-S)

Games

• Indianapolis 500

Related tips

• Indianapolis 500 lighted target opto flags snapped off
• Games that came with Type 2 flipper opto boards
• Every opto dead and the opto board LED off: failed bridge BR5 for the unregulated 12 V

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