1. Without no-load voltage when started:

     ■Magnet field loss

     ■Check AVR reference signal connection

     ■Diode fault

     ■AVR fault

     ■Exciter field winding wiring open circuit(check the winding)

     ■Main rotor winding wiring open

2. Voltage too low

     ■ Check AVR wiring (AVR might have failed)

     ■ Field winding wiring short circuit

     ■Rotating diode damaged

     ■Main rotor winding wiring open

     ■Increase the rev(do not adjust the AVR voltage-potentiometer)

3. Voltage too high

     ■AVR failure

4. Voltage Oscillation

     ■ Check the rev: possibility of nonperiodical oscillation

     ■ Loose connection

     ■ AVR failure

     ■Engine rev is too low at loads or LAN configuration too high

5.The voltage is correct at no load while too low at load.

     ■ Rotating diode failure

     ■ Main rotor short circuit, check resistance

     ■ Exciter armature failure,  check resistance

6. Voltage disappears during operation

     ■ Exciter field winding wiring open circuit

     ■ Exciter rotor failure

     ■ AVR failure

     ■ Main rotor open circuit or short