Open the bottom cover and measured CN2 Samsung SF-700AF switching power supply output of the 10, 8, 6, three-block voltage level display flashes a fight and sometimes without. Unplug the CN2 plugs, voltage from time to time, indicating fault in power supply section (physical mapping as shown in the circuit diagram, see figure). C5 ends for stable 300V DC voltage, unplug the power plug, voltage is not going away, and hear the switching power supply "Squeak" sound, 300V disappears. Focus inspection starting resistors R2, R3, R3 resistance is very unstable (most hours 460K, maximum open circuit), using two 560K ω resistor in parallel after substitution, it recovers.