PURPOSE: To detect the temp. abnormality (both of high temp. and low temp.) of the individual part on a printed circuit board.
CONSTITUTION: The fault diagnostic system of a data processor has an infrared camera 5 judging the surface temp. of a printed circuit board 100, a temp. image display part 6 imagewise displaying the surface temp. of the printed circuit board 100 on the basis of the temp. data from the infrared camera 5, a temp. abnormality judging part 7 processing the temp. data to judge temp. abnormality and a temp. abnormality display part 4 displaying the judgment result.