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Section 1
General Information
Troubleshooting 5-9MN722
Table 5-4 Inverter Section Troubleshooting
INDICATION POSSIBLE CAUSE CORRECTIVE ACTION
No Display Lack of input voltage. Check input power for proper voltage.
Verify fuses are good (or breaker is not tripped).
Loose connections. Check input power termination.
Verify connection of operator keypad.
Bent pins in keypad to control
connector.
Check connector pins and straighten as required.
Adjust display contrast. See Adjust Display Contrast in Sec. 4.
Auto Tune Encoder miswired. Correct wiring problems.
Encoder Test failed
Encoder coupling slipping, broken
or misaligned.
Correct encoder to motor coupling.
Excessive noise on encoder lines. Check the position counter in the Diagnostic Information for
jittering which will confirm an encoder problem.
Use recommended encoder cable.
Check encoder connections including shields.
Separate encoder leads from power wiring.
Cross encoder wires and power leads at 90°.
Electrically isolate encoder from motor.
Install optional Isolated Encoder Feedback expansion board.
Wrong parameter values for “Motor
Base Speed”, “Frequency” or
“Encoder Counts”.
Enter correct parameter values.
Motor coupled to load. Disconnect load then autotune.
Current Sense FLT Open circuit between control board
and current sensor.
Check connections between control board and current sensor.
Defective current sensor. Replace current sensor.
DC Bus High Excessive regenerated power. Increase the DECEL time.
Input voltage too high. Verify proper AC line voltage.
Use step down isolation transformer if needed.
Use line reactor to minimize spikes.
DC Bus Low Input voltage too low. Disconnect dynamic brake hardware and repeat operation.
Verify proper AC line voltage.
Use step up isolation transformer if needed.
Check power line disturbances (sags caused by start up of
other equipment).
Monitor power line fluctuations with date and time imprint
to isolate power problem.
Encoder Loss Encoder power supply failure. Check 5VDC at J1-29 and J1-30.
Also check at encoder end pins D and F.
Check encoder cable continuity.
Encoder coupling slipping, broken
or misaligned
Correct or replace encoder to motor coupling.
Excessive noise on encoder lines. Check the position counter in the Diagnostic Information for
jittering which will confirm an encoder problem.
Check encoder connections.
Separate encoder leads from power wiring.
Use Baldor encoder cable.
Cross encoder wires and power leads at 90°.
Electrically isolate encoder from motor.
Install optional Isolated Encoder Feedback expansion board.
Continued on next page.