PURPOSE: To simplify the wiring work by decreasing the number of wirings by ligthing only a display element in a matrix display circuit which has been placed so as to correspond to a switch by ON of the switch for detecting the abnormality of a cooling fan motor of every display unit.

CONSTITUTION: Switches 101W125 which have been connected like a matrix in accordance with an array of a display unit for constituting a large-sized video display device constitute a matrix switch circuit A, and become ON at the time of fault of a cooling fan motor for cooling each display unit. In this state, when abnormality is generated in the cooling fan motor, the switch corresponding to this cooling fan motor becomes ON, a transistor of a row corresponding to this switch also becomes ON, a display element corresponding to the switch which has detected the abnormality is lighted, and said element operates so that an abnormality display of its switch is executed in a plane position. In such a way, the number of wirings can be decreased, and the wiring work can be facilitated.