Lexmark W820 Service Manual page 97

Error Code 234
There is a paper jam between the Duplex Wait Sensor and
the Registration Sensor.
Logic Control on the MCU PWB sensed that the Registration Sensor did not actuate
within the specified time after the Duplex Wait Clutch was actuated.
Step Actions and Questions
1 PAPER INSPECTION
Inspect the paper that is loaded in the paper cassette.
Is the paper that is loaded in the cassette wrinkled or
damaged?
2 PAPER PATH INSPECTION
Open the Duplex Unit and observe the location of the jammed
sheet of paper.
Is the paper sticking a few inches out of the bottom of the
Duplex Unit?
3 REGISTRATION SENSOR TEST
Enter Diagnostic Mode and select Sensor Test- Registration
Sensor.
Open the Left Upper Cover and insert, then remove, a sheet of
paper into the Registration Sensor.
Does the Control Panel LCD change between OP and CL
as you insert then remove the paper?
4 DUPLEX WAIT CLUTCH TEST
Enter Diagnostic Mode, select Duplex Quick Test.
You can hear and see the clutch "pick" (energize) and the Exit
Roll shaft rotate when the clutch engages.
Does the Wait Clutch actuate and does the Exit Roll rotate
during the Quick Test?
5 EXIT ROLL OBSERVATION
When performing step 4, does the Exit Roll drive the sheet
of paper into the Wait Sensor actuator?
6 MCU PWB REPLACEMENT
Replace the printer Engine Board (MCU PWB). Go to the
printer service manual for the Removal and Replacement
Procedure.
Does the error code appear?
4025 Options
Yes No
Replace the Go to step 2
paper with
new paper
Go to step 3 Go to step 4
Go to step 4 Replace the
Registration
Sensor. Go to
the printer
service
manual for the
Removal and
Replacement
Procedure.
Go to step 5 Replace the
"Duplex
PWB and
Bracket" on
page 4-7
Go to step 6 Replace the
"Exit Roll"
on page 4-12
Go to step 7 Problem
solved
Diagnostic Information
2-15