Since the on-board inverter circuit generally has a power-on soft-start function, the output of the AC 220V will only be available after 5 s-30 s after the power is turned on, and the LED indicator lights up. When the LED indicator is off, it means that the inverter circuit does not work.
When the power is turned on for more than 30s and the LED indicator is not on, you need to measure the AC voltage at the XAC output socket. If the voltage is about 220V, it means that only the circuit of the LED indicator appears. Failure; If the measured AC voltage at the XAC output socket is 0, it indicates that the failure reason is that the inverter circuit at the front stage of the inverter does not work. It may be that the protection circuit inside IC1 has been started.
The method for determining whether the IC1 internal protection circuit is started is to measure the DC voltage value of the IC1 pin 3 with the DC voltage of the multimeter. If the voltage is above 1V, it indicates that the internal protection circuit of the chip has been started; otherwise, the fault is indicated. The reason is due to non-protection circuit action.
If the voltage of pin 3 of the chip IC1 is above 1V, indicating that the internal protection circuit of the chip has been activated, the direct current voltage of the multimeter must be used to block the DC voltage between the 15 and 16 pins of the IC1 and the IC1 of the chip. DC voltage between feet 1 and 2. Under normal circumstances, the 15-pin DC voltage to ground of chip IC1 in the circuit should be higher than the 16-pin DC voltage to ground. The DC voltage of pin 2 to ground should be higher than the DC voltage of pin 1 to ground, only when these two conditions are met simultaneously. When satisfied, the DC voltage of pin 3 of the chip IC1 can be normal 0V, and the inverter circuit can work normally. If it is found that a test voltage does not satisfy the above relationship, the fault can be found by simply pressing the corresponding branch to solve the problem.