Lexmark C 746 Service Manual

							General information1-11
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Input and output sizes and types
Media Sizes
Primary 550-sheet tray
Multipurpose feeder
Optional 550-sheet tray
Optional Speciality 
Media
Optional 2000-sheet
feeder (HCIT)
Duplex
Paper sizes
A4 210 x 297 mm✓✓✓✓✓✓
A5 148 x 210 mm✓✓✓✓ ✓
A6 105 x 148 mm✓✓
JIS B5 182 x 257 mm✓✓✓✓ ✓
Officio (Mexico) 216 x 340 mm✓✓✓✓ ✓
Letter 8.5 x 11 in.✓✓✓✓✓✓
Legal 8.5 x 14 in.✓✓✓✓✓✓
Statement 5.5 x 8.5 in.✓✓✓
Executive 7.25 x 10.5 in.✓✓✓✓ ✓
Folio 8.5 x 13 in.✓✓✓✓ ✓
Universal✓✓✓✓ ✓ 
						

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Envelopes
C6 Envelope 114 x 162 mm
a✓✓
B6 Envelope 125 x 176 mm
a✓✓
C65 Envelope 114 x 229 mm
a✓✓
C5 Envelope 162 x 229 mm✓✓
B5 Envelope 176 x 250 mm✓✓
DL Envelope 110 x 220 mm✓✓
6 3/4 Envelope 3.4 x 6.5 in
a ✓✓
7 3/4
 Envelope 3.4 x 7.5 in ✓✓
9 Envelope 3.9
 x 8.9 in✓✓
10 Envelope 4.13
 x 9.5 in✓✓
11 Envelope 4.5 x 10.4 in
a ✓✓
12 Envelope 4.8 x 11 in
a ✓✓
aThese sizes are accessible using Other Envelope setting.
Media weight, primary tray and option tray
Size Type Weight
Letter, Legal, A4 Xerographic and bond Long grain 60 g/m
2–162.7 g/m2 (16 lb–43 lb)
Short grain 162.7 g/m
2–198.9 g/m2 (43 lb–53.2 lb)
Recycled Long grain 75 g/m
2–177 g/m2 (20 lb–47 lb)
Short grain 105 g/m
2–218 g/m2 (28 lb–58 lb)
Cardstock (maximum) Index long/short 162.7 g/m
2–198.9 g/m2 (90 lb–110 lb)
Cover long/short 162.7g/m
2–198.9 g/m2 (60.1 lb–73.6 lb) 
Tag long/short 162.7g/m
2–198.9 g/m2 (100 lb–122.2 lb) 
Transparencies 161 g/m
2– 179 g/m2 
Thickness: 0.12–0.14mm (4.8–5.4 mil)
Labels Paper 180 g/m
2–300 g/m2 (48 lb–80 lb)
Vinyl 180 g/m
2–300 g/m2 (48 lb–80 lb)  Media Sizes (continued)
Primary 550-sheet tray
Multipurpose feeder
Optional 550-sheet tray
Optional Speciality 
Media
Optional 2000-sheet
feeder (HCIT)
Duplex 
						

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Paper guidelines
Paper characteristics
The following paper characteristics affect print quality and reliability. Consider these characteristics when 
evaluating new paper stock.
Weight—The printer can automatically feed paper weights from 60 to 162l7 g/m
2 (16 to 43 lb bond) grain long. 
Paper lighter than 60 g/m2 (16 lb) might not be stiff enough to feed properly, causing jams. For best 
performance, use 75 g/m2 (20 lb bond) grain long paper. For paper smaller than 182 x 257 mm (7.2 x 10.1 in.), 
we recommend 90 g/m2 (24 lb) or heavier paper.
Note:  Duplex is supported only for 63 g/m
2–170 g/m2 (17 lb–45 lb bond) paper.
Curl—Curl is the tendency for paper to curl at its edges. Excessive curl can cause paper feeding problems. Curl 
can occur after the paper passes through the printer, where it is exposed to high temperatures. Storing paper 
unwrapped in hot, humid, cold, or dry conditions, even in the trays, can contribute to paper curling prior to 
printing and can cause feeding problems.
Smoothness—Paper smoothness directly affects print quality. If paper is too rough, toner cannot fuse to it 
properly. If paper is too smooth, it can cause paper feeding or print quality issues. Always use paper between 
100 and 300 Sheffield points; however, smoothness between 150 and 200 Sheffield points produces the best 
print quality.
Moisture content—The amount of moisture in paper affects both print quality and the ability of the printer to 
feed the paper correctly. Leave paper in its original wrapper until it is time to use it. This limits the exposure of 
paper to moisture changes that can degrade its performance.
Condition paper before printing by storing it in its original wrapper in the same environment as the printer for 24 
to 48 hours before printing. Extend the time several days if the storage or transportation environment is very 
different from the printer environment. Thick paper may also require a longer conditioning period.
Grain direction—Grain refers to the alignment of the paper fibers in a sheet of paper. Grain is either grain long, 
running the length of the paper, or grain short, running the width of the paper. For 60 to 135 g/m
2 (16 to 36 lb 
bond) paper, grain long paper is recommended. For papers heavier than 135 g/m2, grain short is recommended.
Fiber content—Most high-quality xerographic paper is made from 100% chemically treated pulped wood. This 
content provides the paper with a high degree of stability resulting in fewer paper feeding problems and better 
print quality. Paper containing fibers such as cotton can negatively affect paper handling.
Unacceptable paper
The following paper types are not recommended for use with the printer:
•Chemically treated papers used to make copies without carbon paper, also known as carbonless papers, 
carbonless copy paper (CCP), or no carbon required (NCR) paper
•Preprinted papers with chemicals that may contaminate the printer
•Preprinted papers that can be affected by the temperature in the printer fuser A5, JIS B5, Executive Xerographic and bond Long grain 75 g/m
2–177 g/m2 (20 lb to 47 lb)
Short grain 90 g/m
2–218 g/m2 (24 lb–58 lb)
Universal Xerographic and bond Long grain 75 g/m
2–177 g/m2 (20 lb–47 lb) 
Short grain 90 g/m
2–218 g/m2 (24 lb–58 lb) Media weight, primary tray and option tray
Size Type Weight 
						

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•Preprinted papers that require a registration (the precise print location on the page) greater than ±2.3 mm 
(±0.9 in.), such as optical character recognition (OCR) forms
Note:  In some cases, registration can be adjusted with a software application to successfully print on 
these forms.
•Coated papers (erasable bond), synthetic papers, thermal papers
•Rough-edged, rough or heavily textured surface papers, or curled papers
•Recycled papers that fail EN12281:2002 (European)
•Paper weighing less than 60 g/m2 (16 lb)
•Multiple-part forms or documents
Selecting paper
Using appropriate paper prevents jams and helps ensure trouble-free printing.
To help avoid jams and poor print quality:
•Always use new, undamaged paper.
•Before loading paper, know the recommended print side of the paper. This information is usually indicated 
on the paper package.
•Do not use paper that has been cut or trimmed by hand.
•Do not mix paper sizes, types, or weights in the same source; mixing results in jams.
•Do not use coated papers unless they are specifically designed for electrophotographic printing.
Selecting preprinted forms and letterhead
Use these guidelines when selecting preprinted forms and letterhead:
•Use grain long for 60 to 90 g/m2 (16 to 20 lb) weight paper.
•Use only forms and letterhead printed using an offset lithographic or engraved printing process.
•Avoid papers with rough or heavily textured surfaces.
Use papers printed with heat-resistant inks designed for use in xerographic copiers. The ink must be able to 
withstand temperatures up to 190°C (374°F) without melting or releasing hazardous emissions. Use inks that 
are not affected by the resin in toner. Inks that are oxidation-set or oil-based generally meet these requirements; 
latex inks might not. When in doubt, contact the paper supplier.
Preprinted papers such as letterhead must be able to withstand temperatures up to 190°C (374°F) without 
melting or releasing hazardous emissions. 
						

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Storing paper
Use these paper storage guidelines to help avoid jams and uneven print quality:
•For best results, store paper where the temperature is 21°C (70°F) and the relative humidity is 40%. Most 
label manufacturers recommend printing in a temperature range of 18 to 24°C (65 to 75°F) with relative 
humidity between 40 and 60%.
•Store paper in cartons when possible, on a pallet or shelf, rather than on the floor.
•Store individual packages on a flat surface.
•Do not store anything on top of individual paper packages.
Tools required for service
Flat-blade screwdrivers, various sizes
#1 Phillips screwdriver, magnetic
#2 Phillips screwdriver, magnetic
#2 Phillips screwdriver, magnetic short-blade
7/32 inch (5.5 mm) open-end wrench
4.0 mm Allen wrench (HCIT removal)
7.0 mm nut driver
Needlenose pliers
Diagonal side cutters
Spring hook
Feeler gauges
Analog or digital multimeter
Parallel wrap plug 1319128
Twinax/serial debug cable 1381963
Coax/serial debug cable 1381964
Flash light (optional) 
						

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Acronyms
BLDC Brushless DC Motor
BUR Back Up Roll
CCyan
COD Color On Demand
DIMM Dual Inline Memory Module
DRAM  Dynamic Random Access Memory
EP     Electrophotographic Process
ESD    Electrostatic Discharge
FRU    Field Replaceable Unit
GB Gigabyte
HCIT High-Capacity Input Tray
HVPS  High Voltage Power Supply
KBlack
LASER  Light Amplification by Stimulated Emission of Radiation
LCD    Liquid Crystal Display
LED    Light-Emitting Diode
LVPS Low-Voltage Power Supply
M Magenta
MPF Multipurpose Feeder
NVRAM  Nonvolatile Random Access Memory
PC     Photoconductor
pel Picture element (pixel)
POR Power-On Reset
POST  Power-On Self Test
RIP Raster Imaging Processor
SDRAM Synchronous Dual Random Access Memory
V ac Volts alternating current
V dc Volts direct current
YYellow 
						

							Diagnostic information2-1
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2.  Diagnostic information
Start
Use the service error code, user status message, user error message, symptom table, service checks, and 
diagnostic aids in this chapter to determine the corrective action necessary to repair a malfunctioning printer. 
They will lead you to solutions or service checks, including the use of various tests.
Symptom tables
If your printer completes the “Power-on self test (POST) sequence” on page 2-9 without an error, and you 
have a symptom, go to “Symptom tables” on page 2-9. Locate your symptom, and take the appropriate action.
Service errors (1xx.xx/9xx.xx)
If a service error code appears while you are working on the printer, go to “1xx service error codes” on 
page 2-21 or “9xx service error messages” on page 2-38, and take the indicated action for that error.
Service error codes are indicated by a three-digit error code followed by a period and additional numbers in the 
format XXX.YY. In most cases, five digits are shown.
Paper jam messages (2xx.xx)
User attendance messages that indicate a paper jam have been included with the service error codes since 
repeated instances may indicate an underlying service issue. Go to “2xx paper jam messages” on page 2-23. 
User status and attendance messages
•
User status messages provide the user with information on the current status of the printer.
•User attendance messages are indicated by a two-digit code that provides the user with information that 
explains a problem with a print cartridge, option, port, and so on. If a user error message displays, see “3x 
through 8x attendance messages” on page 2-13 or “2xx paper jam messages” on page 2-23.
Additional information
•
“Operator panel and menus” on page 2-2
•“Power-on self test (POST) sequence” on page 2-9
CAUTION
Remove the power cord from the electrical outlet before you connect or disconnect any cable 
or electronic card or assembly for personal safety and to prevent damage to the printer. 
CAUTION—POTENTIAL INJURY:
The printer weight is greater than 54 lbs (24.5kg), and requires two or more trained personnel 
to lift safety. 
						

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Operator panel and menus
C746x operator panel
C746x buttons and light descriptions
Use the To
1 Display • View printer status.
• Allow printer setup and operation.
2 Select button Submit changes made in the printer settings.
3 Navigation buttons Scroll up and down or left and right.
4 Keypad Enter numbers and letters.
5 Sleep button Enable Sleep mode.
The following are the statuses based on the indicator light and the Sleep 
button:.
• Entering or waking from Sleep mode
- The indicator light is illuminated solid green.
- The Sleep button is un-illuminated.
• Operating in Sleep mode
- The indicator light is illuminated solid green.
- The Sleep button is illuminated solid amber.
• Entering or waking from Hibernate mode
- The indicator light is illuminated solid green.
- The Sleep button is illuminated blinking amber.
• Operating in Hibernate mode.
- The indicator light is un-illuminated.
- The Sleep button is blinking amber for 0.1 second, and then goes 
completely un-illuminated for 1.9 seconds in pulsing pattern.
The following actions wake the printer from Sleep mode:
• Pressing any button
• Opening Tray 1 or loading paper in the multipurpose feeder
• Opening a door or cover
• Sending a print job from the computer
• Performing a power.on reset with the
6 Stop/Cancel button Stops all printer activities.
Note: A list of options are displayed once Stopped appears on the display.
7 Back Return to the previous screen.
8 Home button Go to the home screen.
1345
6879 10
12ABC3DEF4GHI5JKL6MNO7PQR8STU9WXYZ0
2 
						

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C748x operator panel
C748x buttons and light descriptions
9 Indicator light Check the status of the printer.
10 USB port Connect a USB Bluetooth adapter or a flash drive to the printer.
Note: Only the front USB port supports flash drives.
Use the To
1 Display • View printer status.
• Allow printer setup and operation.
2 Home button Go to the home screen.
3 Keypad Enter numbers and letters. Use the To
Indicator light 
statusIndicates
Off Printer power is off.
Blinking green Printer is warming up, processing data, or 
printing a job.
Solid green Printer is on, but idle.
Blinking red Operator intervention is required.
1234
6 75
12ABC3DEF4GHI5JKL6MNO7PQR8STU9WXYZ0 
						

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4 Sleep button Enable Sleep mode.
The following are the statuses based on the indicator light and the Sleep 
button:.
• Entering or waking from Sleep mode
- The indicator light is illuminated solid green.
- The Sleep button is un-illuminated.
• Operating in Sleep mode
- The indicator light is illuminated solid green.
- The Sleep button is illuminated solid amber.
• Entering or waking from Hibernate mode
- The indicator light is illuminated solid green.
- The Sleep button is illuminated blinking amber.
• Operating in Hibernate mode.
- The indicator light is un-illuminated.
- The Sleep button is blinking amber for 0.1 second, and then goes 
completely un-illuminated for 1.9 seconds in pulsing pattern.
The following actions wake the printer from Sleep mode:
• Pressing any button
• Touching the screen
• Opening Tray 1 or loading paper in the multipurpose feeder
• Opening a door or cover
• Sending a print job from the computer
• Performing a Power On Reset (POR) with the main power switch.
• Loading paper into the scanner ADF.
• Raising the scanner flatbed cover.
5 Stop/Cancel button Stops all printer activities.
Note: A list of options are displayed once Stopped appears on the display.
6 Indicator light Check the status of the printer.
7 USB port Connect a USB Bluetooth adapter or a flash drive to the printer.
Note: Only the front USB port supports flash drives. Use the To
Indicator light 
statusIndicates
Off Printer power is off.
Blinking green Printer is warming up, processing data, or 
printing a job.
Solid green Printer is on, but idle.
Blinking red Operator intervention is required.