The screen, which has recently been installed in the north-east corner of the stadium on a large glass panel in the Sir John Hall Stand, was due to come into use for the first time for Saturday's game.
However, the turnstiles were yet to be opened at 14.30BST after it was revealed that part of the screen's bracket had come loose - prompting the delay.
Engineer's subsquently scaled the glass panel to secure the screen in place, with kick-off later scheduled for 16.00.
Newcastle posted on their official Twitter account: "An engineer is on site and will make a full appraisal at approximately 3pm. Further information will be available as soon as possible.
"We apologise for the inconvenience caused. We will bring you further information as soon as it is available."
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