HP Laserjet 4 Manual

6Remove the (2) connectors (6 wire and 3 wire). (See Figure
6-15, callout 1.)  Squeeze the release tab on the 6-wire
connector. Pull the 3-wire connector straight up.
7Remove the power supply.
NoteWhen replacing the power supply, be sure to use
the screws with the star washers to ensure proper
grounding and RFI shielding.
Figure 6-15 6-wire and 3-wire Connectors for the Power
Supply
Removal and Replacement  6-17 

Paper Feed Assembly Removal
1Remove the Right Side Cover, the MP opening cover, (see
Figure 6-17), the Top Cover and the Left Side Cover, the Font
Door Cover, and the PC tray (Tray 2). The MP tray need not
be removed, but is shown removed for clarity.
2Remove the MP Tray (Tray 1) door, the Front Cross-member
(Figure 6-11), and the MP Tray.
3Disconnect the 13-wire connector and the 4-wire connector
from the front of the Paper Feed Assembly (see Figure 6-16,
callout 1).
4Remove the (2) screws from the...

(continued on next page)
Figure 6-17 MP Tray Opening Cover
Removal and Replacement  6-19 

5Remove the (3) screws from the left side of the printer (see
Figure 6-18, callout 1).
6Remove the Paper Feed Assembly by lifting it and sliding it
out the front of the printer.
NoteReplace the screws in order as shown. (1-2-3 is
also scribed on the printer chassis.)  Tightening
these screws in the wrong order can cause paper
skew problems.
Figure 6-18 Paper Feed Assembly Screws (numbered)
6-20 Removal and Replacement 

High Voltage Power Supply (HVPS) Removal
1Remove the Toner Cartridge and PC tray.
2Lay the printer on its left side. (Place a cloth under the printer
to prevent marking the cover.)
3Remove the (2) screws that hold the HVPS in place (see
Figure 6-19, callout 1).
4Release the (2) latches that hold the High Voltage Power
Supply (see Figure 6-19, callout 2).
5Pull the HVPS straight away from the printer to clear its
locator pins and to prevent damage to the HVPS connectors.
6Remove the HVPS from its housing...

Fuser Assembly Removal
CautionThe Fuser Assembly may be hot. Allow plenty of
time for the fuser to cool before beginning the
fuser removal procedure.
1Open the rear door.
2Remove the (2) screws that hold the Fuser to the printer
frame  (see Figure 6-20, callout 1).
3Slightly lift the Fuser by both the right and left sides to clear
the locator points. 
4Pull the Fuser from the printer.
NoteThe Fuser Assembly from the LaserJet 4 cannot
be interchanged with the Fuser Assembly from
the LaserJet 4 Plus or 5...

Control Panel and Overlay Removal
1Remove the Right Side Cover and the Top Cover.
2Turn the Top Cover over and place it on flat surface.
3Release the (3) latches that contain the Control Panel (see
Figure 6-21, callout 1).
4Carefully pivot the Control Panel away from the Top Cover.
(continued on next page)
NoteTo remove the LaserJet 5 Control Panel, first
remove the black screw securing the grounding
leaf spring and the Control Panel plate to the Top
Cover.  Release the two latches at the top of the...

5If you must replace the Control Panel Overlay, release the (2)
retaining tabs from the Control Panel and separate the
overlay from the Control Panel (see Figure 6-22, callout 1).
6Squeeze the sides of the Control Panel Overlay to release the
(2) tabs (see Figure 6-22, callout 1).
7Tilt the Overlay up and out.
NoteTo remove the Control Panel Overlay on the
LaserJet 5 printer, first remove the Control Panel
Assembly and  then slide the Overlay out of the
side of the Top Cover.  Reinstalling the Control...

Removing the SIMMs Door 
1Remove the Right Side Cover.
LaserJet 4:
2Remove the (2) screws that hold the SIMMs cover (see
Figure 6-23a, callout 1).
3Open the SIMMs cover, lift the door slightly to remove the
door from the hinge.
(continued on next page)
Figure 6-23a Removing the SIMMs Door (LaserJet 4)
Removal and Replacement  6-25 

LaserJet 4 Plus/5:
2  Remove the (1) screw that holds the SIMMs cover (see
Figure 6-23b, callout 1).
3  Swing open the SIMMs cover.
Figure 6-23b Opening the SIMMs Door (LaserJet 4 Plus)
6-26 Removal and Replacement