These boards have been removed from mostly new MONITORS with broken screens and should work if properly installed. ACER EI491CR MONITOR CONTROL BOARD LJ94-42658A / S490YP01V02 HF CONTROL. Please verify that your board part number is the same as LJ94-42658A / S490YP01V02 HF CONTROL. The part number is the first number left of the /, or the sole number listed. Most often written in title as (part number / board number)