Complex sentence: ABC disappeared from the schedule in 1958 when WJRT-TV signed on from Flint; it served as Lansing's default ABC affiliate until WLAJ signed on in 1990.
Split into simpler sentences: ABC disappeared from the schedule in 1958 when WJRT-TV signed-on from Flint. It served as Lansing's default ABC affiliate until WLAJ signed on in 1990.