Detailed instructions for use are in the User's Guide.
[. . . ] Combined Service Manual
HP LaserJet 4 / 4M (C2001A / C2021A) HP LaserJet 4 Plus / 4M Plus (C2037A / C2039A) HP LaserJet 5 / 5M /5N (C3916A/C3917A/ C3952A)
© Copyright Hewlett-Packard Company 1996 All Rights Reserved. Reproduction, adaptation, or translation without prior written permission is prohibited, except as allowed under the copyright laws. Publication number C3916-90984 First edition, March 1996 Printed in USA
Warranty The information contained in this document is subject to change without notice. Hewlett-Packard makes no warranty of any kind with regard to this material, including, but not limited to, the implied warranties or merchantability and fitness for a particular purpose. [. . . ] When performing these procedures, note the order in which the parts were removed and their orientation. If contamination occurs, clean the bulb thoroughly with isopropyl alcohol.
6-47 Removal and Replacement
Fuser Assembly Configuration Figure 6-40 provides an overview of the orientation of the major Fuser Assembly components. Before beginning the fuser disassembly procedures, become familiar with the location and orientation of the various Fuser Assembly parts (see Table 6-1).
Figure 1-40
Fuser Assembly
Table 1-1
Callout 1 2 3 4
Fuser Assembly Configuration
Assembly Callout 5 6 7 Assembly Fusing Roller Plug to Interconnect PCA Pressure Roller
Exit Sensor Flag Thermistor Thermoswitch Heat Lamp
6-48 Removal and Replacement
Removing the Fuser Roller Heat Lamp
Figure 1-41
Fuser End Cap Removal (LaserJet 4 only)
1 Laser Jet 4 only: Remove the (2) latches that hold the right
side cover. (There is a gear exposed on the right side of the fuser, see Figure 6-41, callout 1. ) 2 Release the (7) latches on the LaserJet 4 or the (5) latches on the LaserJet 4 Plus that hold the wire cover to the Fuser Assembly. (continued on next page)
6-49 Removal and Replacement
Figure 1-42
Fuser Wire Harness Cover Removal (LaserJet 4)
3 LaserJet 4: With a screwdriver, release the latches by first
pressing to clear the lower latch, then lifting to release the upper latch (see Figure 6-42a). LaserJet 4 Plus: With a screwdriver, release the latches by first pressing to clear the lower latch, then lifting to release the upper latch. Repeat until all (4) latches are free, then rotate the cover to release the latch on the side (see Figure 6-42b and 6-42c). Note Six of the seven latches are accessed from the top of the wire cover. The slot on the front left side of the wire harness cover is the best place to begin removing the cover.
6-50 Removal and Replacement
Figure 1-42b
Fuser Cover End Latches (LaserJet 4 Plus)
Figure 1-42c
Fuser Wire Harness Cover Removal (LaserJet 4 Plus)
(continued on next page)
6-51 Removal and Replacement
Figure 1-43
Left Side Fuser Cover
5 Remove the (1) Heat Lamp lead (thermoswitch screw)(see
Figure 6-43 callout 1).
6 Press the thermoswitch tab towards the paper exit flag to
release the tab (see Figure 6-43 callout 2). Slide the Thermoswitch off the fuser frame (see Figure 6-43, callout 3). 7 LaserJet 4: Remove the cable retainer from the fuser frame, and free the heat lamp lead from the cable retainer. LaserJet 4 Plus/5: Remove the (2) screws from the end cover (see Figure 6-43, callouts 4 and 5). Note the wavy washer on the (1) screw touching the copper contact (see Figure 6-43, callout 4). Remove the thermistor connector from the frame and pull apart (see Figure 6-43, callout 6). Note the position of the Fuser Shipping Lever and remove from assembly. (continued on next page)
6-52 Removal and Replacement
Figure 1-44 Note
Gear Side Heat Lamp Connector LaserJet 4 and 5 only: Note the orientation of the bushing on the left side of the Fusing Roller.
8 Squeeze the lamp connector to release the slip-on connector
locking tab from the right side of the heat lamp (see Figure 6-44, callout 1). (continued on next page)
6-53 Removal and Replacement
Figure 1-45 Note
Fuser Gear Cap Removal Before removing the gear cover, note the routing of the wires in the gear cover slots.
9 Remove the (2) screws from the right side gear cover (see
Figure 6-45, callouts 1 and 2). Note the wavy washer on the (1) screw (callout 1) touching the copper contact. 10 Remove the Heat Lamp (see Figure 6-45, callout 3), from the roller. Pull the lamp out the side of the assembly.
6-54 Removal and Replacement
Fuser Assembly Thermoswitch Removal Note Six of the seven latches are accessed from the top of the wire cover. The slot on the front left side of the wire harness cover is the best place to begin removing the cover.
1 Remove the Wire Harness Cover as shown in Figure 6-42a
(LaserJet 4) or Figure 6-42b and c (LaserJet 4 Plus).
2 Remove the (2) screws from the Thermoswitch connector (see
Figure 6-46, callout 1).
3 Release the thermoswitch latch from the paper sensor flag
side of the Fuser Assembly (behind the side cover). 4 Slide the Thermoswitch to the gear side of the fuser and release it from the fuser frame (callout 3).
Figure 1-46
Fuser Thermoswitch Connectors
6-55 Removal and Replacement
Thermistor Removal
Figure 1-47
Thermistor Connector
1 Remove the Wire Harness Cover as shown in Figure 6-47. [. . . ] This tool for troubleshooting IR communication problems, shown in Figure 10, has been developed by Genoa Technology, Inc. , in cooperation with Hewlett-Packard. The part number is 5062-4661 and can be ordered through HP Parts Direct Ordering. The IR test tool can be used with any IrDA-compliant primary or secondary device, regardless of manufacturer.
IR Diodes
Test
LB
Connect Pass
Peripheral Test
Computer Test
Test Modes PCL Printer PostScript Printer Energy Detect Test Frame
itch sw es
Figure B-8
Infrared Test Tool
To test the peripheral device:
1 Put the HP LaserJet 5 in Ready Mode. If the "PASS" LED lights, the test was successful, indicating that communication with the printer's IR port is functioning normally.
LaserJet 5/5M/5N Printer B-39
On HP Laser-Jet printers, a self-test page will be initiated by the test. [. . . ]