Baldor mn722 manual Inverter Section Troubleshooting

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	Check connector pins and straighten as required.
	connector.
	Adjust display contrast.	See Adjust Display Contrast in Sec. 4.
Auto Tune	Encoder miswired.	Correct wiring problems.
Encoder Test failed
	Encoder coupling slipping, broken	Correct encoder to motor coupling.
	or misaligned.
	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	Enter correct parameter values.
	Base Speed”, “Frequency” or
	“Encoder Counts”.
	Motor coupled to load.	Disconnect load then autotune.
Current Sense FLT	Open circuit between control board	Check connections between control board and current sensor.
	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	Correct or replace encoder to motor coupling.
	or misaligned
	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.

MN722 Troubleshooting 5-9