First boot detection D board connector D7, 2 feet of the DC voltage is 0V, indicating that the main switching power supply rectifier filter circuit is not working, accordingly, and press the power switch instant relay action sound, judge the fault is certainly some reason caused by switching of the power supply of the electrical RL801 constant in a reset condition caused by. Detection Q852 base voltage is 0V, then micrometer processor IC1213{33} pin voltage, found in the secondary boot flash instantaneous jump phenomenon, which shows that the remote control circuit can output second start of high level instruction, faults may IC1213 is 6 feet connected with the protection of circuit elements adverse caused by misoperation caused. Try a short piece of wire short connected d1104 at both ends, the IC1213 is 6 feet constant in low 0V potential, and then start to detect IC1213{33} pin voltage for normal 4.8V, then testing relay drive pipe Q852 base voltage 0.1V apparently boot high level is not transmitted to the base of the Q852. The Q856 base voltage is 0.65V, which indicates that the Q856 is in a saturated state, and the high level of the output of the microprocessor is short. Due to the time of the switch power supply and the output circuits were not working, the Q856 electric potential of the base electrode of elevated is remote control power supply overvoltage and overvoltage protection and monitoring device D857 variable value, leakage or integrated protection circuit Q857 set emitter junction breakdown etc.. D857 anode pin voltage is 0.6V, which excludes the remote control power supply voltage and D857 bad factors. Then detection Q857 of B, C, e source voltage followed by 4.7V, 4.5V, 4.8V (normal should be respectively 5V, 0V, 4.8V). Based on combination of circuit principle of failure and maintenance of inference Q857 C E - very serious leakage, replacement of the tube, short term found in the boot of standby indicator red luminous tubes instantaneous bright once went out after turn green indicator light, also figure, photoacoustic appeared normal. At this time off after demolition external in the IC1213 is 6 foot jumper, reboot and try and work machine back to normal.