Common Faults of Inverter-2
Inverter Fault Diagnosis and Maintenance
1. There is no display on the keyboard after power-on:
1. Check whether the input power supply is normal. If it is normal, measure whether the voltage at the P and N terminals of the DC bus is normal. If there is no voltage, turn off the power and check whether the charging resistor is damaged or not.
2. After checking that the voltage of P and N terminals is normal, you can replace the keyboard and keyboard cable. If there is still no display, you need to check whether the 26P cable connecting the main control board and the power board is loose or damaged.
3. If the switching power supply works normally after power-on, the relay has the sound of pulling in and closing, the fan operates normally, and there is still no display, it can be determined that the crystal oscillator or resonance capacitor of the keyboard is broken, and the keyboard can be replaced or repaired at this time.
4. If everything else is normal after power on, but there is still no display, the switching power supply may not be working. At this time, it is necessary to unplug the P and N terminal power supplies after power failure, and check whether the static state of IC3845 is normal (check by experience). If the static state of IC3845 is normal, the voltage at both ends of the 18V/1W zener diode is about 8V after the DC voltage is applied to P and N, but the switching power supply does not work. Power off and check whether the rectifier diode on the secondary side of the switching transformer has a breakdown short circuit.
5. After power on, the 18V/1W Zener diode has voltage, but there is still no display. You can remove some peripheral plugs, including the relay wire plug and the fan wire plug, and check whether the fan and relay have short circuits.
6. After the P and N terminals are powered on, the voltage across the 18V/1W Zener diode is about 8V. Use an oscilloscope to check whether there is a sawtooth wave at the input terminal ④ of IC3845, and whether there is output at the output terminal ⑥ pin.
7. Check whether there is a short circuit between the output terminals +5V, ±15V, +24V of the switching power supply and the drive power supply of each road to the ground and between the poles.
