Measured switching power supply 115V 40V voltage output is only about measuring line pipe Q501Ve pole on the ground, the reverse resistance values ​​were 2kΩ, 2.5kΩ, suspect a problem with the line pipe, remove the measure properly. Then test the line flyback capacitors, resistors at both ends of the road test C510 is very small, measuring properly remove the C510, D503 breakdown analysis may be.Gjbservice manual download site

Replace the D503, turn and burn. To analyze the reasons for the breakdown D503 can be C509 (1500pF) and C510 (0.056μF) partial pressure is not normal due. According to C509, C510's capacity calculation, D503 ends of the reverse voltage does not exceed 3.0V (static), D503 breakdown again, the fundamental reason is C509 problem. Remove C509 measure its leakage resistance of approximately 2kΩ, replace the C509, the D503, the machine is working properly.Gjbservice manual download site