SC750 User Manual

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Service Manual: SC750, SC800, SC 750 ST, SC800 ST

Form Number 56043150 Page 91

Troubleshooting

Scrub Motors Do Not Turn On

Possible Causes

• Brush Contactor

o Open or shorted winding

o Burned contacts

• Wiring

• Main Machine Controller – Not energizing the brush contactor.

• Drive Motor Controller – Not providing “machine moving signal”

Brush Head Will Not Raise or Lower

Possible Causes

• Mechanical binding for the actuator linkage

• Brush Head Actuator – Check both the motor and the posion switches. Only one posion switch should be open

at a me and it should open at the correct posion.

o Actuator Motor

 Unplug the actuator connector and momentarily supply fused 24v power and ground to the

two motor terminals to see if the motor will operate. (Machine harness wire color Pink wire and

Gray wire). Reverse the polarity to drive it in both direcons. If the motor will not drive in both

direcons, replace the actuator. If it does drive in both direcons, proceed to check the posion

switches.

o Posion Switches

 Access the Main Machine Controller and unplug the electrical connectors.

 Check the retracted posion switch.

• Put the black ohmmeter lead on the Brown wire at the J2 connector pin 2.

• Put the red ohmmeter lead on the White wire at the J2 connector pin 3.

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Nilfisk SC750 Heavy-Duty Cleaning