A player or a team is “lighting up the scoreboard” when points are being scored. However, the scoreboard is usually always lit, even when the score is zero. The expression became popular in the 1940s and 1950s and is still used, despite improved scoreboard technology.
 
“Lit up the scoreboard” has been cited in print since at least 1943, “light up the scoreboard” since 1950 and “lighting up the scoreboard” since 1952.
 
 
17 September 1943, Dallas (TX) Morning News, “Wolves Roll Over Wildcats, 19 to 6, in High School Grid Opener” by John Zischang, sec. 1, pg. 9, col. 4:
A James-to-Garrett pass over the goal line, and a vagrant kick by Willis lit up the scoreboard with Tech 13, Wildcats 0.
 
15 December 1945, Monessen (PA) Daily Independent, “Monessen High Drops Washington, 44-20,” pg. 5, col. 2:
Heath lit up the scoreboard in the first half-minute of play by dropping a foul, followed by Compson’s successful attempt at the charity line.
 
Google Books
13 January 1950,

, “Rough Sledding in Winter Sports” by Dan D. Coyle, pg. 11, col. 1:
Unfortunately “if’s” and personal fouls don’t light up the scoreboard and the Tigers, after holding Syracuse to a 33-29 halftime edge, faded in the stretch and bowed, 80-48.
 
25 February 1952, The Monroe County News (Albia, IA), “Mitchell Gives the Darling Treatment to Blakesburg,” pg. 6, col. 2:
While Mitchell was lighting up the scoreboard fioni the pay-off end of the methodical Lacey’ at-tack, his mates were holding Blakesburg shooters in check.
 
6 December 1952, Lubbock (TX) Morning Avalanche, “New Deal Advances,” sec. 1, pg. 8, col. 5:
Both teams waxed the floor the second period with a total of 25 points falling through the hoops, 13 lighting up the scoreboard for Cotton Center.
 
1 January 1954, San Diego (CA) Union, “Uclans Engage Michigan State,” pg. B-5, col. 1:
Employing a complex offense that makes use of both the T and wing-back formations, Munn is an acknowledged genius at lighting up the scoreboard.
 
24 February 1954, Morning Advocate (Baton Rouge, LA), “Pettit’s Departure Marks End of Era” by Hugh A. Mulligan (AP), pg. 4-B, col. 7:
Pettit’s name and fame were electric, lighting up the scoreboard with a consistency never seen before in the Bayou State.
 
USCTrojans.com—The Ripsit Blog
Lighting Up the Scoreboard
By Jordan Moore on April 7, 2014 9:56 AM
USC women’s lacrosse is riding its hottest streak in program history with four consecutive wins thanks to a dynamic offense which put up 20 goals in Sunday’s win over Cal.
 
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Nicho
‏@Nicho_Saenz
Its halftime and the spurs are lighting up the scoreboard #NBAPlayoffs #spursvsblazers
9:49 PM - 8 May 2014