This is the infrared Transmitter assembly in the white plastic housing with a green circuit board used on many late model Bally and Williams playfield mechanisms.

Reference:

A-16908
B-79711 is the set of Receiver with housing and Transmitter with housing assemblies.
A-14231 is the WPC System opto transmitter board without the white plastic housing. You can unscrew the bad board from the housing and replace with the A-14231 board.