Skyjack SJ61T - Generator Troubleshooting

Page 228 December 2007
Telescopic Boom Series
Models SJ61T & SJ66T
194312
Section 5 - ProceduresService and Maintenance
5.11-2 Generator Troubleshooting
Problem Cause Remedy
Generator not rotating - Motor not turning - Check for proper hydraulic flow
- Directional valve not working - Check voltage to coil
- Bad coil or valve
- Broken drive key - Check and replace
Frequency falls under load - Hydraulic flow to motor falling - Check flow to motor is constant
- Bad motor - Replace motor
Generator does not excite - Low speed - Check and adjust speed
- Faulty capacitor - Check and replace
- Breakdown in windings - Check winding resistance
High no-load voltage - Excessive speed - Check and adjust speed
- High capacity of capacitor - Check and replace
Low no-load voltage - Low speed - Check and adjust RPM
- Faulty rotary diodes - Check and replace
- Worn windings - Check winding resistance
- Low capacity of capacitor - Check and replace
- Low speed when loaded - Check and adjust RPM
- Excessive load - Check and repair
- Short-circuited diodes - Check and replace
- Check and adjust speed
Unstable voltage - Poor contacts - Check connections
- Uneven rotation - Check for uniform rotation speed
Noisy generator - Broken bearings - Replace bearings
- Poor coupling - Check and repair
1177AA
Proper no-load but low loaded
voltage
Proper voltage in no-load
conditions but high voltage at load
- High speed in loaded
condition