When the power is turned on, first standby circuit work first, standby circuit should have the following output voltage, negative end of the D105 to 5V, the negative end of the D104 14V, IC102 7818 tripod for 18V, voltage above normal, standby circuit normal.
When the standby voltage is normal, we put the CN8007 8 feet and 9 feet short, equivalent to 8 feet to a low level. When short circuit, open the power supply should be able to hear the sound of the relay, at both ends of the bridge rectifier should have voltage, if the relay does not work, the first 4 feet to measure what the PC131S No. whether for low level (normal, the feet should be low level), from this point up to judge, fault is in the PC131S or in the circuit. If high voltage is 4 feet PC131 No., please measure about R717 voltage should normally be 3V, if the voltage is low, please check Q712 and Q714 whether has been conducting. If the guide, prove the protection circuit has been action, please find out which way to protect, and then check the corresponding circuit. If the protective circuit is normal, please check the Q715 whether to have damaged; if PC131S of No. 4 feet of voltage is normal, please check the d132 and Q131 is damaged.
If the voltage relay, please measure C204, C205 ends, normal should be 380V. If it is 300V, please check the PFC circuit; if the normal 380V, please measure CN8005 No. pin 1 of voltages VA, CN8002 of No. 2 feet of VG 15V voltage, CN8004 of No. 3 feet with the voltage of 12V, CN8008 of No. 2 feet a 3.3V voltage, voltage above is normal.
Note that the VA voltage and the other voltage are divided into two transformers, which are performed by two separate circuits, which are treated separately, which are subject to the problem and must be checked for the relevant circuits.
If the above voltage is normal, we can CN8008 No. 9 feet [VS-ON] and No. 10 feet [v] shorted, equivalent to the logic board to No. 9 feet with a high level, this time vs control circuit should work vs should have output voltage. If no output, first check the control circuit, 4 feet to measure what the PC202S No. is the high level should normally be 8V. If the voltage is low, please check PC202S itself and Q207. If the 8V is normal, please measure IC203 3 pin voltage, normal 4.2V. Usually, IC203 damage to the more often the q206 and Q205 burnt phenomenon; No. 3 pin voltage if the normal. Please check a IC203 peripheral circuits.