After a combing, there are about seven factors that can lead to faults related to other voltage detection, such as the inverter POFF or OU:
1. Input voltage detection circuit alarm failure, such a fault is obtained due to short alarm light-coupled 3, 4 feet problems;
2. KM state detection circuit alarm failure, repair point in the short report of optical coupling 3, 4 feet;
3. DC voltage detection circuit, to confirm the input to the MCU pin of the detection voltage value is normal;
4. The voltage of the supply of 5VMCU is low, triggering POFF or other related alarms, such as communication anomalies;
5. Processing current, voltage, temperature signal of the ungraded circuit, the drive maintenance often introducea -2.5V or 2.5V reference voltage, in order to achieve the positive and negative detection signal to 0 to 5V signal purposes, in order to confirm the normal ity of the reference voltage;
6. In the MCU's VREF pin, there is also a reference voltage introduction, often for the reference of the internal A-D conversion, when the voltage anomaly, will lead to internal data calculation errors, false positiveOU, LU or OL, OH and other failures;
7. When the internal EEPROM memory internal data (such as rated current, DC loop voltage, etc.) abnormal, LU, OU, OL and other false alarm.
Combined above, in the maintenance of the drive with the above-mentioned fault phenomenon analysis, may be the EEPROM memory internal data anomalies, triggering POFF or E-07 false alarm. In order to verify that the fault judgment is normal, the memory 24C04A on the same MCU motherboard is switched with the memory on the faulty motherboard, powered up, displayed and operated normally.
The repair of such failures, there is a certain degree of chance, such as lenovo is not eEPROM memory problems, there will be an unrepairable end.
Sometimes, ideas determine the way out. General maintenance personnel, may be overhauled to 1, 2, 3 aspects of the reason, and 4, 5, 6, 7, it is shown as a difficult fault. The maintenance of 4, 5, 6, 7 inverter failure, and the maintenance experience of the inverter maintenance personnel, and even the ability of association, have a great relationship.