Lexmark C 746 Service Manual

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27S2837 M3.5X1.34 panhead 
8L, blackLeft cover to lower frame 2
Rear left cover through lower swingout frame into left cover 1
Rear right cover to rear upper cover 1
Rear upper cover to top cover 1
Top cover to right cover 1
27S2838 Machine M3X0.5–
6GLContacts assembly to left/front edge of printer frame 2
Fax modem blank plate to left plate 1
ISP blank plate to left plate 2
Second USB connector to left frame 1
System board USB connector to frame 1
USB-A Blank plate to left plate 1
27S2839 Taptite M3 L6 
Taptite slotted hex 
blackRear cover frame to frame 8
88A0003 Machine M3X0.5-
6G 8LPrinthead 3
88A0095 M2.5x10 Machine 5 V interlock switch actuator assembly 1
24 V interlock switch and shield to right frame 1
88A0212 Taptite M3.5x0.6 
PANFuser AC cables ground wire to left plate 1
88A0232 Taptite M3 L6 
PANHDCartridge right guide assembly to rightside plate 10
Lower plate to lower swingout frame assembly 1
Lower swingout frame assembly to left frame assembly 4
Lower frame support to right frame assembly 4
88A0233 Taptite M3 L8 
PANHDLower swingout frame assembly to leftside frame assembly (rearmost 
position)1 Screw identification table (continued)
P/N Screw type Location Qty 
						

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88A0293 Plastite M2.2 L5 Contact spring cap to left guide assembly 4
88A0312 Plastite M2.9 L6 
PANBackup springs to reference edge plate assembly 2
Cartridge cooling fan duct to top cover 2
Cartridge left guide assembly to leftside plate assembly (exterior side of plate 
assembly)4
Cover mount to rightside plate 3
Display detent spring to display back bezel 1
Door straps to front access door cover 2
Door bracket to front access door cover 2
Duplex entry guide to front access door cover 4
Exterior screws attaching cover bracket to front access door cover 2
Front cover bracket to front access door cover 4
Ground terminal/operator panel card to top access door cover CBM 1
Lower frame support to lower left frame assembly 2
Operator panel card to top access door cover CBM 3
Option locator to rightside plate 1
88A0313 Plastite M2.9 L8 
PANContacts assembly to leftside cartridge guide 1
Cover bracket to front access door cover 2
Cover pivot to swingout frame 3
HVPS to transfer contact assembly 3
HVPS to leftside cartridge guide assembly 2
Interior screws attaching cover bracket to front access door cover 2
88A0323 M3.5X1.34 Panhead 
8LDuplex upper guide to top access door cover CBM 9
Ground strap/contact to front door frame 1
Lower right frame to right side plate 3
Pick assembly to lower plate 4
Secures reference edge assembly to door assembly 2
Static brush bracket to top access door cover CBM 1
Torque tube cover to front door frame 6
88A0324 M3.5X1.34 PANHD 
10LEP drive to rightside plate 2
Secures door cap to door assembly 1 Screw identification table (continued)
P/N Screw type Location Qty 
						

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88A0412 M2.9x5.2 Plastite GS COD bell cranks to guide 3
NGS COD bell cranks to guide 3
Top access door assembly to fuser retract link 1
Top cover left link to cover 1 Screw identification table (continued)
P/N Screw type Location Qty 
						

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Adjustments
Printhead alignment
Overview
When aligning the printhead, it is important to keep in mind that the printhead mounting screws should be initially 
loose enough to just hold the printhead in the printer. This allows the pages to be printed that will be used to 
align the black plane to the printer frame and also allows skew adjustment with the printhead alignment screw. 
Once the black skew is adjusted, the mounting screws are fully tightened.
There is one printhead that houses the four color planes. The black plane is aligned to the printer, and the color 
planes are internally aligned to black. Electrical alignment is done to fine tune the alignment of the color planes 
to the black plane once the printhead is installed and skew is adjusted.
The first step in aligning the printhead is to loosen the printhead mounting screws, and to set the skew for black. 
Note:  If you need to replace the printhead, see “Printhead removal, installation, and adjustment” on 
page 4-145. 
Printhead mechanical alignment (C746)
Skew (black)
1.Turn off the printer.
2.Disconnect the power cord from the electrical outlet.
3.Remove the transfer module and photoconductor units:
a.Disconnect the transfer module cable (A). 
b.Press the two tabs (B) to release the front access cover assembly.
c.Press the two tabs (C) on either side of the transfer module, and lift out the transfer module.
Note:  Leave the photoconductor units on the transport belt when removing. 
To avoid damaging the photoconductor drum, place the transfer module with the photoconductor 
units on a clean surface. Never expose the photoconductor units to light for a prolonged period of 
time. You can place a clean, dry cloth over the transfer module and photoconductor units until they 
are required.
BC
A 
						

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4.Loosen the printhead mounting screws in the following order: D1, D2, and D3.
5.Remove the printhead alignment screw cover (E).
6.Reinstall the transfer module with the photoconductor units still attached.
7.Reconnect the transfer module cable. 
8.Replace the toner cartridges. 
9.Close the top access door. 
10.Close the front access door.
11.Plug the electrical cord into the printer.
12.Plug the electrical cord into the outlet. 
D2D3
D1
E 
						

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13.Align the printhead skew for black. 
a.Enter the Diagnostic menu (turn off the printer, press and hold buttons 3 and 6, turn on the printer, 
and release the buttons when the clock graphic displays).
b.Select REGISTRATION from the DIAGNOSTICS menu, and select Settings.
c.Select Skew, and press  .
d.Use   or   to set the Skew to zero, and press  .
e.Scroll down to Quick Test, and press  . A page similar to this one prints: 
						

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f.Adjust the printhead alignment screw (G) to change the skew and straighten the image on the 
printout.
If the top right alignment marks are lower than the top left alignment marks, rotate the alignment 
screw counterclockwise a full revolution, and print the Quick Test page. Repeat adjusting the screw 
and printing the Quick Test until the top alignment marks are the same distance from the top of the 
media.
Note: One rotation of the printhead alignment screw equals approximately 0.5 millimeter movement 
of the top edge print alignment marks.
g.When the top right and top left alignment marks are both showing and are even on the page, the 
skew is aligned.
G
Straight Skewed 
						

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14.Tighten the printhead mounting screws.
a.Turn off the printer.
b.Disconnect the power cord from the electrical outlet.
c.Disconnect the transfer module cable. 
d.Press the two tabs on either side of the transfer module, and lift out the transfer module with the 
photoconductor units in place.
e.Remove all of the toner cartridges.
f.Tighten the printhead mounting screws in the following order: H1, H2, and H3.
15.Replace the printhead alignment screw cover.
16.Replace the toner cartridges. 
17.Reinstall the transfer module and the photoconductor units.
18.Connect the transfer module cable. 
H2H3
H1 
						

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Registration (black)
Top Margin
1.Reconnect the power cord to the electrical outlet, but do not turn on the printer yet.
2.Enter Diagnostic mode (press and hold buttons 3 and 6, turn on the printer, and release the buttons when 
the clock graphic displays).
3.Select REGISTRATION, and press  .
4.Select Quick Test, and press   or use the last Quick Test you used to adjust skew.
5.Select Top Margin, and press .
6.Adjust the values until both top alignment marks are on the top edge of the print. 
•Increasing the value ( ) moves the top alignment marks down on the page. 
•Decreasing the value ( ) moves the top alignment marks up on the page. 
7.Press   to save the value. 
8.Print the Quick Test page, and check the top alignment marks. Repeat adjustment of the top margin and 
printing of the Quick Test page until top margin is set.
Bottom Margin
1.Select Bottom Margin, and press  . 
2.Adjust the bottom margin until the points of the bottom margin alignment marks are visible and touching 
the edge of the paper.
•Increasing the value ( ) moves the bottom alignment marks up on the page.
•Decreasing the value ( ) moves the bottom alignment marks down on the page.
3.Press   to save the value. 
4.Print the Quick Test page, and repeat this process until the bottom margin is adjusted. 
						

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Left Margin
1.Select Left Margin, and press  .
2.Adjust the left margin until the points of the left alignment marks touch the edge of the page.
•Increasing the value ( ) moves the left alignment marks away from the edge of the page.
•Decreasing the value ( ) moves the left alignment marks toward the edge of the page.
3.Press   to save the value. 
4.Print the Quick Test page, and check the left alignment marks each time until you are satisfied.
Right Margin
1.Select Right Margin, and press  .
2.Adjust the right margin until the points of the left alignment marks touch the edge of the page.
•Increasing the value ( ) moves the right alignment marks away from the edge of the page.
•Decreasing the value ( ) moves the right alignment marks toward the edge of the page.
3.Press   to save the value. 
4.Print the Quick Test page, and check the results. Repeat if necessary.
5.When the registration is complete, proceed to the color alignment.
Alignment (cyan, yellow, and magenta)
1.
Press   until you reach the top menu.
2.Select ALIGNMENT MENU, and press  .
3.Select Cyan, and press  . 
4.Select Top Margin, and press  .
5.Use  and  to set Top Margin to zero, and press   to save the value.
6.Do the same for Left Margin, Right Margin, Bottom Margin, Skew, and Bow. 
It is important to set all the values to zero before starting.