HP 4 Plus Manual
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Formatter Cage Removal NoteYou may wisht to remove the metal cover (on the lower right side) and the power supply for easier access to the Formatter Cage screws. 1Remove the Right Side Cover and the Top Cover. 2LaserJet 4 and 5: Remove the (7) screws (6 screws in the LJ 5) shown in Figure 6-24a. (2) screws are on the right rear of the printer, (1) screw is under the lower front of the Formatter Cage (except LJ 5). LaserJet 4 Plus: Remove the (3) screws shown in Figure 6-24b (one screw is located behind the SIMM door), and the (2) screws on the right rear of the printer (shown in Figure 6-24c). 3Remove the Rear Door Support Strap. 4Slide the Formatter Cage straight out the right side of the printer, being careful not to damage the Formatter/DC Controller pin connectors. (continued on next page) Figure 6-24a Formatter Cage Screws (Right Side View - LaserJet 4 and 5) Removal and Replacement 6-27
Figure 6-24b Formatter Cage Screws (Right Side View -LaserJet 4 Plus) Figure 6-24c Formatter Cage Screws (Rear View - LaserJet 4Plus) 6-28 Removal and Replacement
Formatter PCA Removal CautionThe Formatter PCA is very sensitive to Electro- static Discharge (ESD) damage. Observe proper ESD procedures when servicing the printer. NoteBefore removing the old Formatter PCA, print a 05 SELF TEST to check the current printer page count, if possible. If a self test is not possible, enter the Service Mode, if possible, to display the page count (see “Service Mode ” in Chapter 3). Remove the Formatter Cage from the printer before beginning the Formatter PCA removal procedure. After the Formatter Cage is removed, remove the Formatter PCA as detailed on the following pages. (continued on next page) Removal and Replacement 6-29
LaserJet 4 Formatter PCA: 1Remove any MIO or SIMM modules from the Formatter Assembly. 2Remove the (2) black screws from the side of the Formatter Cage (see Figure 6-25a, callout 1). 3Remove the MIO Connector Support Bracket (see Figure 6-25a, callout 2). 4Remove the (2) Formatter PCA mounting screws (see Figure 6-25a callout 3). (continued on next page) Figure 6-25a Formatter Cover and PCA Mounting Screws (LaserJet 4) 6-30 Removal and Replacement
5Remove the (4) Interface Connector Support Screws from the rear of the Formatter Cover. The RS-232 connector is held with 5mm hex-head cap screws (see Figure 6-25b, callout 1). The parallel connector (see Figure 6-25b, callout 2.) is held in place with Phillips screws. 6Remove the Formatter PCA. Note When replacing the Formatter Assembly be sure to reinstall all SIMM modules and MIO cards. Be sure to reset the page count and the Cold Reset paper size after replacing the Formatter. (continued on next page) Figure 6-25b Interface Connector Support Screws (LaserJet 4) Removal and Replacement 6-31
LaserJet 4 Plus and 5 Formatter PCA 1Remove any MIO or SIMM modules from the Formatter Assembly. 2Remove the MIO Connector Support Bracket (see Figure 6-25a, callout 2). 3Remove the (4) I/O screws (see Figure 6-26 callout 1). 4Remove the (2) Formatter PCA mounting screws (see Figure 6-26 callout 2). Note When replacing the Formatter Assembly be sure to re-install all SIMM modules and MIO cards. Be sure to reset the page count and the Cold Reset paper size after replacing the Formatter. Figure 1-26 Interface Connector Support Screws (LaserJet 4 Plus and 5) 6-32 Removal and Replacement
DC Controller Removal NoteNote the cable routing before beginning this disassembly procedure. Be careful not to damage the cables during re-assembly. 1Remove the Right Side and the Top Cover Assemblies. 2Remove the Formatter Cage Assembly. 3Remove the 6-wire connector from the Power Supply. 4Remove the plastic DC Controller cover (LaserJet 4 Plus). 5Remove the DC Controller connectors (see Figure 6-27a or 6-27b, callout 1). 6Release the DC Controller from its retaining clips (2) and remove the DC Controller (see Figure 6-27a or 6-27b, callout 2). Figure 1-27a DC Controller Connectors/Retaining Clips (LaserJet 4) 6-33 Removal and Replacement
Figure 1-27b DC Controller Connectors/Retaining Clips(LaserJet 4 Plus/5) 6-34 Removal and Replacement
DC Controller Installation CautionWhen reinstalling the DC Controller PCA it is extremely important that all cables be properly routed. If cables are not routed properly, it is difficult to reinstall the Formatter Cage and cable damage may result. When replacing the DC Controller, be sure to set the leading edge adjustment as shown in the following procedure. Note The Leading Edge Adjustment is set at the factory and is not required as a maintenance procedure. The Leading Edge Adjustment should be done only when the DC Controller is replaced. The following procedure is performed with the Formatter Assembly removed. To set the Leading Edge Registration: 1Install the new DC Controller in the reverse order of the removal. 2Run a test print to check the leading edge adjustment (as shown in Figure 6-28. 3Use VR202 (LaserJet 4) or VR201 (LaserJet 4 Plus and 5) (see Figure 6-29) to adjust the leading edge registration to the dimension shown in Figure 6-28 (a=2mm). 4Make several test prints ( 15 ENGINE TEST as shown in Figures 3-5 and 3-6) and check the adjustment. Repeat the above steps until the adjustment is correct. 6-35 Removal and Replacement
Figure 1-28 Leading Edge Registration AdjustmentDimensions Figure 1-29 VR202 Settings (LaserJet 4 shown) 6-36 Removal and Replacement