Lexmark E 450 Dn Service Manual

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Controller card removal 
Warning:  
•Always touch a ground before touching the card. 
•Handle the card carefully by the edges.
•Never replace the operator panel and controller card at the same time without a successful POR in 
between.
1.Remove the right side cover. See“Right side cover removal” on page 4-5.
2.Remove the controller card cover.
3.Disconnect all the cables from the controller card, and remove cables from the shield housing. 
Warning:  Do not replace the controller card and the operator panel at the same time. Each card contains the 
printer settings. When either of these cards is new, it obtains its settings from the other card. Critical 
factory settings are lost when both are new and replaced at the same time. 
4.Remove the four screws (A) that are securing the controller card. 
						

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5.Remove the three screws (B) securing the USB port and the parallel ports. 
6.Lift and remove the card.
Re-installation note: When replacing the controller card, make sure to route all of the cables through the 
correct shield opening. Make sure that the ground wire that is being held by the front, upper screw is in the 
correct location before installing. 
						

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Cover open sensor removal
1.
Remove Tray 1.
2.Open the front cover.
3.Open the right side cover. See steps 1 and 2 of “Right side cover removal” on page 3-5.
4.Remove the controller card cover.
5.Loosen the one screw (A) from the shield that protects the sensor.
6.Disconnect the cable from J6 on the controller card.
Note:  The cable has a toroid. Be sure to remove the toroid before removing the cable.
7.Use a small Phillips screwdriver to remove the screw (B) holding the sensor. 
8.Remove the sensor.
Reinstallation note: 
•Be sure to re-route the cable back through its retainer.
•Be sure to place the toroid back over the cable. 
						

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Developer drive coupling assembly removal
1.
Remove the left side cover. See “Left side cover removal” on page 3-4.
2.Place the machine on its right side.
Note:  Be sure to protect the machine from marring.
3.Remove the six screws (A), the machine screw (B), and the ground cable screw (C).
4.Lift the main motor drive, and disconnect the motor cable (D). 
ABC 
						

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5.Remove the coupling spring (E). 
6.Remove the developer drive coupling (F).  
						

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Duplex removal
1.
Remove the right side cover. See “Right side cover removal” on page 3-5.
2.Remove the left side cover. See “Left side cover removal” on page 4-4.
3.Remove the top cover. See “Top cover removal” on page 3-7.
4.Remove the controller card. See “Controller card removal” on page 4-13.
5.Remove the LVPS/HVPS card assembly. See “LVPS/HVPS card assembly removal” on page 3-26.
6.Unhook the media level indicator. See “Media level indicator removal” on page 3-33.
7.Remove the top LVPS/HVPS shield:
a.Remove the screw (A) and the screw (B) at the controller shield.
b.Remove the screw (C) opposite from screw (B) on the other side of the printer.
Note:  The ground cable is attached to screw (C). When re-installing, be sure to reconnect the ground cable.
8.Remove the media level indicator. See “Media level indicator removal” on page 3-33. 
						

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9.Remove the six screws (D). 
10.Lift the right side (opposite the coupler) and remove the duplex.
Note:  At re-installation, before tightening the screws, locate the duplex unit against the left side frame. (Left side 
relative to the picture above.) 
						

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Duplex gear drive
1.
Remove the main motor drive. See “Main motor drive removal” on page 3-28.
2.Remove the duplex. See “Duplex removal” on page 4-18.
3.Remove the duplex coupling and gears (A) (the screw and plastic retainer).
4.Remove the duplex coupling (B) and mating link.
Note:  The link (not shown) that connects the duplex and duplex coupling is part of this FRU as well as the 
duplex FRU. 
						

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Fan removal
1.
Open the right side cover. See steps 2 through 4 of “Right side cover removal” on page 3-5.
2.Remove the two screws (A) holding the fan to the side frame.
3.Unplug the cable from J4 on the controller card.
Note:  Be sure to remove the toroid before removing the cables. When re-installing, be sure to place the toroid 
back over the same cables.
4.Remove the cable from its retainer.
5.Remove the fan.
Flag removal (top cover right)
1.
Remove the top cover. See “Top cover removal” on page 3-7.
2.Turn the top cover upside down.
3.While lifting the flag with your thumb to align the shaft flats with the holder, use the spring hook to slide the 
flag out of place, and remove.
Note:  The left flag was found to be not needed and has been removed from the FRU list. 
						

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Fuser removal
1.
Remove the left side cover. See “Left side cover removal” on page 4-4.
2.Remove the right side cover. See “Right side cover removal” on page 4-5.
3.Remove the rear cover. See “Rear cover removal” on page 4-6.
4.Loosen the top cover by removing the one rear screw above the reverse solenoid. Release the side 
latches, and lift the rear of the top cover.
5.Remove the paper exit guide assembly. The gears of the exit guide must clear the fuser bracket without 
touching it. See “Paper exit guide assembly removal” on page 4-37 for more information.
6.Remove the two screws (A) and the one machine screw (B) that secures the ground cable. 
7.Disconnect the thermistor cable above the fuser. 
8.Remove the controller card cover.
9.Disconnect the exit sensor cable from J11 on the controller card.
10.Disconnect the fuser power cable above the fuser.