Thursday, November 24, 2011

HP LaserJet 42X0/43X0 -- Swing Plate Replacement

Swing plate replacement is not a difficult job. We strongly advise against the short-cut method of replacing only the rearmost black gear. That's not a legitimate short-cut; it's a job half done that will soon fail.

A machine with badly worn swing plate gears will have a lot of gear tooth fallout fouling other gears. If at all possible, such machines should be repaired in a shop equipped with compressed air and a parts washer tank.

Proceed as follows:

1) Cartridge

2) Tray 2

3) Back Door
- Pry right side hinge inward to free hinge pin.

4) Top Rear Cover
- Pull it straight up.

5) Right Side Rear Cover (Formatter Cover)
- Pull it straight back.

6) Duplexer Slot Insert (if present)
- Pull it straight back.

7) Tray 2 Rear Concealment Cover
- Tip it up and pry loose its left side hinge pin.

8) Fuser

9) Cartridge Engagement Arm
- Disconnect it from the cartridge access door and lower it.
- NOTE: The arm must be fully lowered for swing plate assembly
removal and replacement.

10) Top Cover Assembly
- Four M3x8mm washerhead screws.
- Lift cover up an inch.
- Disconnect control panel cable -- right side near the middle.
- Lift the cover away completely.


11) Formatter Cage
- Two M3x6mm bright washerhead screws at the rear.
- Pull the item straight rearward to unplug/remove it.

12) Right Side Cover
- One large claw at upper rear.
- One tab at arrowhead in front behind tray 1 door.
- One claw at arrowhead in front just below tray 1 door.
- NOTE: MIND the switch rod/rocker connection when reinstalling this cover.

13) Left Side Cover
- One claw at top centre.
- One claw at arrowhead in front behind tray 1 door.

14) Fan Connector Cover P/N RC1-0344 (Sheet metal rectangle below fan on left side.)
- Two M3x8mm washerhead screws at locations ‘M3’.

15) Fan and Thermistor Cable Connections
- NOTE: Make certain that the cable ends are outside the chassis where they can't get snagged when removing and reinstalling the power supply.

16) Right Side Duplexer Way
- Two M4x10mm bright pan head threading screws.
- One latch button at arrowhead; slide the item rearward to
remove it.

17) Switch Rod
- NOTE that the long, straight arm goes outboard.

18) Two Flat Cables

19) Three Red Cables (Does not apply to 4300.)

20) DC Power Cable

21) Pull the cables into the tray 2 cavity

22) Power Supply
- One M3x6mm bright pan head screw w/captive washer at right
side.
- Three M3x8mm washerhead screws at right side.
- Three M3x8mm washerhead screws at left side.
- MIND THE CABLING AS YOU PROCEED.
- Lift the back end of the unit slightly and it can be slid
out the rear. Take care not to damage the two flat cables.

23) Power Supply Right Side Way
- One M3x8mm washerhead screw just above the formatter
connector.
- One latch button; slide the item rearward to remove it.
- Replace the screw with a 4mm long washerhead screw, and the screw will no longer interfere with removal/replacement of this item.

24) Rectangular Grommet below swing plate assembly
- Two claws. Push the grommet inward so it’s clear of the
swing plate assembly.

25) Swing Plate Assembly
- WARNING: Use only a high quality No. 2 Phillips screwdriver
in perfect condition for this. The screws are usually very
tight, and must not have their recesses reamed by cam-out.
The awkward placement of the screws would make a reamed
screw recess very difficult to deal with.
- NOTE: The swing plate comes away quite easily, but it can be remarkably difficult to get one into place. Try to observe the path it takes as you remove it to gain familiarity with its fit. Remember that the cartridge engagement arm must be fully lowered for the swing plate to go in.
- Three M3x6mm black washerhead screws.

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Gear Cleaning

As mentioned earlier, several gears are likely to be fouled with debris from worn swing plate gears.

The large gear that drives the swing plate can't be removed easily; it must be cleaned in situ. It should be lightly greased once cleaned.

The large gear next to that gear has a claw-latch; it can be removed easily for cleaning. There's no need for grease to be applied to it -- it's very lightly loaded; all it drives is the little 'conveyor-belts' affair at the upper front of the power supply assembly.

If the fuser is good to reuse, its gears will likely need cleaning.

The gearing associated with the delivery assembly is not difficult to take out for cleaning. See this post for some help with that.

- - -

SWING PLATE REINSTALLATION NOTES

a) There are two small white plastic glide-buttons plugged into rectangular holes in the swing arm. Check that they are both present and properly seated.

b) Check that the swing arm retraction spring is in place, that the swing arm pivots freely, and that the spring pulls the swing arm back to its stop smartly and fully.

c) Swing plate reinsertion is accomplished by tipping the upper portion of the assembly up in behind two plastic parts. Here's a view of the part's attitude as it's just about to go into place easily.


d) It’s a good practice to replace the three washerhead screws with hex head screws. It will be easier to tighten the screws with a nutdriver, and any subsequent swing plate assembly replacement will be easier.

e) When properly installed, raising the cartridge release arm should cause the fuser drive gear to lift. Lowering the cartridge release arm should permit the fuser drive gear to drop. THE FUSER DRIVE GEAR MUST DROP FREELY AND SMARTLY TO ITS ENGAGEMENT POSITION. IT MUST NOT BIND.

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