| Failure | Cause | Treatment | 
|     Can not power  |         Alternator    | Wiring mistake | Check and correct according to wiring diagram | 
| Severe defects such as broken line of rotor winding or excitation winding      | Check relevant winding resistance by the universal meter, and if winding resistance is infinite, broken line should be connected. If winding resistance is zero, it should replace or process coil.  | 
| Broken line of alternator stator winding and excitation winding  | Check resistance by the universal meter, and if resistance is infinite, broken line should be connected. | 
| Rotating-rectifier module breakdown and short circuit  | Check forward reverse resistance by the universal meter and when it shows zero, rotating-rectifier module changes.   | 
| AVR | The output lead wire is not connected.
 | Connect lead wire | 
| The fuse is damaged.  | Change the fuse in the inner voltage regulator. | 
| Voltage regulator is damaged. | Change voltage regulator | 
| No load voltage  is too low or  too high | alternator | The rpm of alternator is too low or too high.  | Adjust generator speed to rated speed  | 
| Excitation winding is rare short.    | The current of exciter’s excitation winding is large. Excitation winding is serious heat and big vibration. Excitation winding’s DC resistance is smaller than its normal value. It needs the return-to-factory service | 
| Rotating-rectifier module is at fault.  | Open NDE-shield’s cover back plate sheet,disconnect F1 or F2 joint, check rotating-rectifier module by the universal meter. If forward reverse resistance does not accord with the requirement of the properties of the diode, it changes damaged rotating-rectifier module. | 
| AVR | Wiring mistake   | Check whether wiring circuit is correct  | 
| Erroneous measure voltage causes low output voltage or unadjustable.  | 
| Voltage setting point is too low or too high.    | Adjust voltage set potentiometer in clockwise or counterclockwise  direction until voltage meets with requirement.   | 
| Remote voltage setting point is too low or too high.  | Adjust remote voltage setting potentiometer in clockwise or counterclockwise direction until voltage meets with requirement. | 
| Voltage regulator is damaged. |  Change voltage regulator |