Abstract：To introduce two fault cases in the use of STORZ 20134020 cold light source. The first fault was sudden shutdown in use,
and could not be started again. After inspection, the cause of the fault was that the main engine fuse was burned out and the main
control circuit board was damaged. The second fault was that the cold light source was turned on and the display was normal, and
the xenon lamp bulb did not light up. Through the reverse circuit schematic method, circuit schematic diagram of the critical fault
area of the circuit board was drawn. Through fault analysis, the damaged components were found to be ML4824IS1 power factor
compound control chip, field effect tube P12NM50, patch triode K2T, patch diode T4, diode RURP3060 and high voltage discharge
tube EPCOS5000, and the equipment was successfully repaired. The fault maintenance analysis in this paper put forward the method
of analyzing circuit board fault by reverse circuit schematic diagram, which should be a method to improve the maintenance skills of
chip level, and provide reference for the maintenance peers.
