Lexmark MB790MFP Service Manual page 166

Step
10 Check the sensor (duplex input) for proper operation.
1. Enter the diagnostic mode
2. Select Duplex tests
3. Select sensor test
4. Observe the line item "input"
Does the display on the operator panel, change every time
the sensing area of the above sensor is interrupted or
blocked.
11 Check the above sensor for proper connection.
Is the above sensor connected properly?
12 Perform a print test and check the duplex drive motor
assembly for proper operation.
Does the above component operate properly?
13 Check media origination.
Did the media originate from the external duplex?
14 Check the sensor (duplex input) for proper operation.
1. Enter the diagnostic mode
2. Select Duplex tests
3. Select sensor test
3. Observe the line item "input"
Does the display on the operator panel, change every time
the sensing area of the above sensor is interrupted or
blocked.
15 Check the sensor (duplex exit) for proper operation.
1. Enter the diagnostic mode
2. Select Duplex tests
3. Select sensor test
3. Observe the line item "exist"
Does the display on the operator panel, change every time
the sensing area of the above sensor is interrupted or
blocked.
16 Check the two pick roll assemblies in the media tray being
picked from.
Are the above components free of excess wear and
contamination?
17 Check the aligner assembly for obstructions.
Is the above component free from obstructions?
Check Yes
Go to step 12. Go to step 11.
Replace the Replace the
Sensor (duplex connection.
input).
Go to "Sensor
(duplex input)
removal" on
page 4-41.
Go to step 17. Replace the
duplex drive motor
assembly.
Go to "Duplex
drive motor
assembly
removal" on
page 4-9.
Go to step 14. Go to step 16.
Go to step 15. Replace the
external duplex
assembly.
Go to step 17. Replace the
external duplex
assembly.
Go to step 17. Clean or replace
the pick roll
assembly.
Go to "Pick roll
assembly
removal" on
page 4-31
Go to step 18. Remove
obstructions.
Diagnostic information
7462
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