Lexmark C750 Service Manual page 159

Front door is open, no indication on display
Step Action and questions
1 Make sure the front door is activating the cover switch.
Is the door activating the cover switch?
2 Check door—door switch activating tab (broken or
missing).
Is the front door and door activating tab damaged,
broken or missing?
3 Check the front door magnetic latches to make sure the
front door closes correctly.
Are the magnetic latches functioning properly?
4 Check the front door switch cable connection to CN11
on the finisher system board.
Is the cable connected correctly?
5 Check the continuity of the front switch as the switch is
activated.
Do you measure continuity?
6 Check continuity of the front door switch cable.
Do you measure continuity?
Fan in finisher inoperative
Step Action and questions
1 Make sure the fan cable, H6, is correctly connected to
CN21 on the finisher system board.
Is the cable connected correctly?
2 Check the cable H6 connection to the fan assembly.
Is the cable connected correctly?
3 Check the voltage between CN21-1 and CN21-2. The
voltage measures approximately +24 V dc.
Is the voltage correct?
4 Check continuity of the fan cable H6.
Do you measure continuity?
Yes No
Go to step 2 Repair or replace
the door assembly.
Replace the front Go to step 3
door assembly.
Go to step 4 Replace the
magnetic latches.
Go to step 5 Install the cable
correctly.
Go to step 6 Replace the front
door switch.
Replace the Replace the front
finisher system door switch
board. cable D1.
Yes No
Go to step 2 Install the cable
correctly.
Go to step 3 Install the cable
correctly.
Go to step 4 Replace the
finisher system
board.
Replace the fan Replace cable H6.
assembly.
Diagnostic information
5060-00x
2-125