HP Laserjet 4 Manual

Removing the Switchback Paper Guide
1Remove the (1) E-clip from the shaft on the stepper motor side
shown in Figure A-11, callout 1.
2Pull the shaft toward the left and out of its track.
3Rotate the shaft 90 degrees to remove it from the metal paper
guide solenoid arm.
Figure A-11 Switchback Paper Guide
Duplexer   A -15 

Removing the Paper Guide Assembly
1Remove the (4) screws shown in Figure A-11, callout 2.
2Lift the switchback assembly and clear the wires.
3Remove the assembly.
Note: When re-assembling, verify proper wire routing
as shown in Figure A-12, callout 1.
Figure A-12 Wire Routing and Upper Switchback Guide Screw
A -16  Duplexer  

Removing the Paper Roller
1Remove the (1) screw below the Switchback Solenoid Arm on
the gear side as shown in Figure A-13, callout 1.
2Remove the sensor, squeezing the tabs on the underside of the
sensor (see Figure A-13, callout 2).
(continued on next page)
Figure A-13 Solenoid Arm
Duplexer   A -17 

3Remove the (1) screw shown previously in Figure A-12,
callout 2. Remove the upper switchback paper guide by
releasing its latch with a flat screwdriver and pushing to the
side. 
4Remove the (4) screws on top of the sheet metal part of the
upper paper guide shown in Figure A-14, callout 1.
(continued on next page)
Figure A-14 Upper Paper Guide Sheet Metal
A -18  Duplexer  

5Remove the (1) E-clip from the gears on the shaft on the
Power PCA side shown in Figure A-15, callout 1. 
6Rotate the bushings and lift the roller out.
Figure A-15 Gears on Paper Roller
Duplexer   A -19 

Removing the Control PCA 
1Remove the (2) screws shown in Figure A-16, callout 1.
2Remove the cover plate.
(continued on next page)
Figure A-16 Cover Plate
A -20  Duplexer  

3Unplug all connectors from the Control PCA. 
NoteThe Control PCA connectors are keyed.
4Remove the (4) screws shown in Figure A-17.
5Disconnect the connector from the power supply.
6Remove the PCA.  
Figure A-17 Control PCA
Duplexer   A -21 

Removing the Power PCA
1Remove the (6) cover screws, (4) on the top and (2) on the side.
Remove the cover.
2Remove the (4) screws from the Power PCA (see Figure A-18,
callout 1).
3Unplug the connector (see Figure A-18, callout 2).
4Lift the Power PCA out of the duplexer.
Figure A-18 Power PCA
A -22  Duplexer  

Removing the Holding Tray Center Paper Guide
 
1Remove the Control PCA as described earlier.
2Remove the (2) screws from the plate located on the power
PCA side of the duplexer (see Figure A-19, callout 1).
3Lift off the guide.
Figure A-19 Plate on Power PCA Side of Duplexer
Duplexer   A -23 

Removing the Holding Tray Belt
1Remove all the screws securing the plate (see Figure A-20,
callout 1).
2Remove (1) E-clip shown in Figure A-20, callout 2. 
3Remove the bushing underneath the E-clip.
4Release (2) latch points shown in Figure A-20, callout 3.
Note: The (2) washers on the gear beside the bushing
are now loose.  Remove and set aside.
5Release the wires from the wire holder, allowing the cover to
move aside to access the gears.
(continued on next page)
Figure A-20 Holding Tray Belt Cover...