Lexmark C760 Service Manual

Diagnostic information2-125
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Operator panel LCD/status LED/buttons service check 
Use this service check to check both the operation of the panel buttons and to test the LCD display for correct 
operation.
Replace the operator panel assembly if the LCD display functions normally, but the LED does not come on.
If one or more of the operator panel buttons do not operate correctly, go to “Step A.”
 If any of the following symptoms occur, go to  “Step B” on page 2-135.
Operator panel LCD is...

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8Operator panel cable (operator panel connection) - 
Make sure that the operator panel cable is seated 
correctly in the connector on the operator panel board.
Is the cable seated correctly?Go to step 9 Seat the cable 
correctly
9Operator panel cable - Check continuity of the operator 
panel cable.
Is there continuity? Replace the 
“System board” 
on page 4-72
Go to 
“Operator 
panel” on 
page 4-53  and 
replace the 
operator panel 
cable
10System board - A poor ground...

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Output expander option service check
Note:  The majority of the mechanical components can be observed during operation by removing the covers. 
The output expander functions without the covers installed. Make sure the option is correctly installed before 
attempting to service the unit.
Step Symptoms Yes No 1 The printer does not recognize one or more output 
expander options as being installed. Go to 
“Printer 
does not 
recognize that 
one or more 
output options...

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Printer does not recognize that one or more output options as being installed.
Remove Paper - Output Bin x is displayed, POST is incomplete unable to clear the 
message.
Step Actions and questions Yes No
1 Excessive static electricity buildup - Check the output 
expander control board cover to make sure the ESD 
brush ground lead is firmly attached to the output 
expander frame. Make sure the ESD brush is not loose 
or damaged.
is the ESD brush ground cable correctly...

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No indication that bin  x is full or no indication that bin  x is near full.
Problems with excessive static electricity buildup.
Step Actions and questions Yes No 1 Sensor cable installation - Check for correct installation 
of the sensor cable at J5 on the control board.
Is the cable installed correctly? Go to step 2 Install the cable 
correctly
2Dual output bin x sensor assembly
Do either the bin  x full or the bin  x near full sensor fail 
the sensor test? Go to...

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Print quality service check
Note:  This symptom may require replacement of one or more CRUs (Customer Replaceable Units) designated 
as supplies or maintenance items, which are the responsibility of the customer. With the customers permission, 
you may need to install an ITU, fuser assembly, second transfer roll, or print cartridge.
Check the following before proceeding with any of the print quality service checks.
Use tray 1 (internal tray) to test the print quality of...

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Entire page is mostly one color—Full bleed planes in one color
Some printing may appear in other colors. This applies to black, cyan, magenta and yellow.
Step Action and questions Yes No 1 Using a piece of paper, block the laser path between 
the printhead and cartridge for the color that is 
experiencing the full bleed issue. Go to step 2 Go to step 4
2Turn the printer off. Check the cable connections 
between the printhead and the system board.
Does the issue...

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Missing colors—Complete or partially missing color planes

If a color or colors are missing, or a color is partially missing, go to  “If cyan, magenta, and yellow is 
missing, go to “Black and white only—cyan, magenta, and yellow are missing” on page 2-133.” on 
page 2-132 .
If cyan, magenta, and yellow is missing, go to  “Black and white only—cyan, magenta, and yellow are 
missing” on page 2-133 .
Step Action and questions Yes No 1 Print cartridge - Make sure the...

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Black and white only—cyan, magenta, and yellow are missing
Light print over the entire page

If all colors have light print, go to  “All colors have light print over the entire page” on page 2-133 .
If only one color has light print, go to “One color has light print over the entire page” on page 2-134 .
All colors have light print over the entire page
8Perform a continuity check on the developer HVPS 
cable.
Does the cable check out?Replace in order:
1. Developer...

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One color has light print over the entire page
Vertical lines or streaks
Horizontal lines or streaks
If the horizontal marks or lines repeat at evenly-spaced intervals, use the “Print quality defect locator chart” 
on page 3-4  to determine the part to be replaced.
For lines or marks appearing at random intervals, go to step 1. Step Action and questions Yes No
1 Print cartridge - Make sure the cartridge is seated 
properly and all packaging material is removed from 
the...