My grandfather was a sound engineer at Wimbledon, and my family all remember rushing to look at the TV to see him fixing the umpire's microphone. We're trying to find a recording of this incident, which lasted a few minutes.
To the best of our combined knowledge it was the women's final or semi-final in the late 1970's, possibly early 1980s - most likely 1978-1980.
We've found a couple of complete matches on the The Greatest Championships playlist at the official Wimbledon channel on Youtube (1978 and 1980 womens finals, Evert/Wade semi 1977, and Navratilova/King quarter 1980) but it doesn't seem to be any of those.