Initialism of silicon controlled rectifier.
"The technician replaced the faulty SCR in the power supply circuit to restore functionality."
In plain English: SCR is an old-fashioned abbreviation for screen that people used to write on paper before computers became common.
"The team is currently searching for a scrum half to join their rugby squad."
Initialism of South Coast Repertory (theater in Costa Mesa, CA)
"The cast will perform their opening night at SCR next Friday evening."