Lexmark T63X/64X -- Autocompensator Ball Clutch & Axle

Occasionally, you'll encounter a ball-clutch/axle assembly where the parts of it won't stay put as they should; they tend to wander off axially. The main, outboard portion of the clutch tends to move rightward, as does the axle.

To secure the clutch's hub to the axle, you can apply CA adhesive and let it wick in between the clutch's hub and the axle, but there's a risk of overdoing the glue application and fouling the clutch. A safer, more elegant way to do it is to install a tiny threading screw through the hub and into the axle. Here's a view of that done.

The screw is an M2x6mm one that I got from a T640's fuser exit sensor. A 1/16" diameter hole accepts the screw perfectly. Spot the hole's location with an awl; drill the hole with a pickup roller in place so as to be certain of ending up with the hub properly positioned axially. That hub will never wander again.

To restrain the axle from shifting rightward, apply a small (three-inch) ty-wrap around the axle as a 'retaining ring' just to the left of the beam's hub. Here's a view of that.

Install the ty-wrap as tightly as you can possibly get it.

With those two modifications made, the ball-clutch/axle assembly will retain its axial position and behave itself.

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FEEDBACK

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Oki 320/1 Turbo -- Early Engineering Changes

Revision 'A' and early revision 'B' machines had changes made to four parts -- the space rack backup roller, the paper path change lever, the rear feed paper-out sensor toggle and the rear feed paper-out sensor flag. Following is an explanation of the changes, and a further improvement to the paper-out sensor flag that we came up with here at West Hill Printers.

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Space Rack Backup Roller

At the left in the above photo is the early, plastic roller. The revised item with a steel ball bearing for a roller is at the right.

The early rollers were prone to flat-spotting. That would lead to poor space motor pinion engagement with the space rack. The pinion would jump teeth on the space rack. The user would see it as margin drift, with the occasional space alarm fatal error when the carriage would crash a stop.

The new roller is P/N 40917101.

Paper Path Change Lever

The early change lever was prone to let the change gear slip out of mesh with the rear tractor drive gear. Oki lengthened the change gear displacement surface on the change lever to solve that. Pictured below are the two versions of change lever.

[I've blackened the changed portion to make it more discernable.]

At the left is the original lever. At the right is the modified lever with its extra change gear displacement surface. You need only remove a printer's cover to be able to see the affected portion of a lever to check whether the new-style part has been installed. The part number for a new-style lever is 50809501.

The lever is force-fitted onto a splined shaft.To remove one, proceed as follows:

1) Remove platen.

2) Remove the gear train's reset leaf spring and all three gears.

3) Set the change lever to its centre (friction feed) position.

4) Apply one screwdriver as a fulcrum, and a big-enough plain slot screwdriver as a lever in this manner.

You'll be able to pry the part loose with no risk of breaking anything, although there's a claw on the lever at the inner wall of the chassis that may break off if you don't deflect it forward.

To install a new lever, get the lever in position at the end of the splined shaft with the flats lined up. Then, use a pair of Channellock pliers to press the new part onto the shaft, like so.

I should be using slightly larger Channellocks. The ones in the photo are just barely adequate.

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Rear Feed Paper-Out Sensor Toggle

The change to this part is subtle, but it does seem to make cut-sheet sensing more reliable. Here's a view of the old and new parts.

The old part is at the left, the new part is at the right. Note the different profiles. The part number for the new part is 50809301.

Remove the platen and the platen cradle to gain access to the part. Pry gently to pop the part out of its pivot points.

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Rear Feed Paper-Out Sensor Flag

This will always be a weak point, no matter what's done to it.

The part is deflected by paper presence. When the paper is gone, the part is supposed to return to its at-rest position by force of gravity. The part's 'axle' gets fouled with paper dust eventually, and hangs up in its deflected position. The printer is then always sensing a paper-in condition. If you try to park continuous forms, the forms will unload entirely -- the printer can't tell when the forms' leading edge has left the sensor.

To get at the part, remove the platen, platen cradle and the logic PCA at the left side. Here's a view of three versions of the part.

At the top is the original part. Below it is Oki's improved version. Note the relieved axle -- it's less prone to fouling with paper dust, but it still fouls eventually. The part number for the new version is 40775901.

A further change that Oki made was to add a cover over the axle's pivot cradle. That's pretty much useless; I just take them off and discard them when overhauling a printer.

At the bottom is the part with our modification made to it. We add an M3x6mm pan head screw to the head of the part to give it more weight and make it more responsive to gravity. It's an improvement, but paper dust fouling remains inevitable.

To install the modification, you'll need a drill press and a 7/64" drill. Spot the hole location with an awl. Set up the drill press' depth stop for a drilling depth of 1/4" and drill the hole for the screw.^[1]

A 7/64" diameter hole is an interference fit for an M3 screw. Drive the screw all the way in; it will end up securely in place.

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Note

[1] This is doable directly on the drill press' table, there's no need for a drill press vise, but it will seem a bit awkward until you get accustomed to it.

The plastic material exhibits variations in density that allow the drill to seek the path of least resistance at times, resulting in an imperfect but not ruined outcome.

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FEEDBACK

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HP LaserJet 42X0/43X0 -- Delivery Assembly & Duplexing Pendulum Assembly Removal

The gearing in these two units tends to get fouled with debris when a swing plate has worn badly. The assemblies are easily removed for a proper gear cleaning.

All that's holding the delivery assembly in place is a single swing-latch bearing at its right side. Here's a view of it.

And here's the bearing unlatched and on its way out.

With that bearing removed, the right side of the delivery assembly can be lifted, and the assembly can be shifted rightward to free it from the left side vertical frame member. (There's a small sensor cable at the right side that has to be freed from a slot.)

The duplexing pendulum is fastened by two M3x8mm washerhead screws. It comes out easily, but it's one of those parts that can be disorienting when you go to reinstall it. Here's a view of it in the machine with the delivery assembly removed.


There's no need to grease any of the gears, just apply WD-40 to their spindles.

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FEEDBACK

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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.

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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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FEEDBACK

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HP LaserJet 4100 -- "Perform Printer Maintenance" Message

Maintenance Interval

Maintenance interval is 200,000 pages.

Clearing the Message

To clear the message, press and hold '-Item' and -'Value' while powering on the printer. Release the keys when you see " RESET MAINT COUNT" in the display. The MAINTENANCE COUNT item in the Service Menu gets reset to zero.

Clearing the Message Temporarily

This is a user convenience feature that permits one to put off seeing the message for another 10,000 pages. In the Configuration Menu there'll be an item, MAINTENANCE MESSAGE = OFF. Select it, and the message will go away for awhile.

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FEEDBACK

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HP LaserJet 4100 -- Routine Teardown/Overhaul

The 4100 has two weak points that routinely cause paper jams, and should be attended to when performing a routine overhaul:

a) The pickup solenoids become sticky with age. See this post for more information, and a repair method

b) A roller clutch on the paper feed assembly is prone to gum up and slip. See this post for service information.

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Proceed as follows:

1) Cartridge

2) Tray 2

3) Tray 2 Rear End Cover (if present)
- Two claws high up, accessible through small rectangular openings.

4) Back Door
- Open it and pry at the right side hinge to free the door.

5) Fuser
- Two lock levers.

6) Rear Right Side Cover (Formatter Cover)
- Tug it rearward to remove it.

7) Control Panel Overlay
- Pry at its right side lip to free two small claws.

8) Control Panel
- There's a claw at either side near the front. Nudge them with a small screwdriver to free them.
- One cable connection.

9) Top Cover
- Two M4x12mm bright pan head threading screws at the back.
- Two M4x12mm bright pan head threading screws under the toner cartridge access door.
- Cartridge engagement arm -- free its upper end.
- Pry at the right front to free the right front corner.
- Tug the front of the cover up forcefully to free it.
- NOTE: The door's hinges are easily separated to facilitate washing the door and cover.

10) Front Right side Cover
- One claw at the top.
- NOTE: MIND the switch rocker/rod engagement when reinstalling this cover.

11) Left Side Cover
- Lift it slightly and tip it away.

12) Tray 1 Door
- Pry gently to free the inner platform from its ways.
- Slide the door rightward off its hinges.

13) Tray 1 Platform w/Sensor Arm Cover and Torsion Spring
- Disengage the torsion spring.
- Tug forcefully on the sensor arm cover to pop it off the pickup shaft.
- Lower the platform a bit and it can be slipped off its left side hinge pin.

14) Two Extended Head M4 Screws near the Front
- The left side screw is visible by the yellow cable for Tray 1's paper-out sensor.
- The right side screw's head is just below and to the right of the envelope feeder connector.

15) Tray 1 Pickup Assembly w/Left Side Cartridge Guide
- One in-line cable connection for the pickup solenoid.
- One cable connection for the paper-out sensor.
- Five M4x12mm bright pan head threading screws in front. Three of them are in deep wells.
- INSPECT the pickup solenoid for stickiness.

16) Paper Feed Assembly
- One in-line cable connection.
- Two M4x12mm bright pan head threading screws. NOTE that these are in the upper holes of the brackets. The two lower holes are where two of the Tray 1 pickup assembly's screws go.

17) Cover-Open Switch Bracket
- One M3x6mm bright pan head screw w/captive star washer at blue ground wire terminal.
- One M4x12mm bright pan head threading screw forward of and below the previous screw.
- Free the bracket and let it dangle by the side of the machine.

18) Registration Assembly
- One M3x6mm bright pan head screw w/captive star washer at the extreme right.
- NOTE. There is an M3 hex head screw forward of and to the left of the previous screw. DO NOT loosen it.
- Five M4x12mm bright pan head threading screws.
- Overhaul per this post.

19) Pre-Transfer Ground Plate
- Tip up its right side end and slip it out.

20) Delivery Assembly
- The left side white bearing unhooks easily and lifts out.
- The right side bronze bearing has a lever on it. Swing the lever up to vertical and the unit can be lifted out.
- Overhaul per this post. (Scroll down to "To dismantle...".)

21) Printhead
- Three cable connections.
- One M3x8mm pan head threading screw at blue ground wire terminal.
- Four M4x12mm bright pan head threading screws.
- DO NOT DISTURB the hex recess head screw at the centre rear. It was factory-adjusted for optical skew correction.

22) Formatter Cage
- One M3x6mm bright washerhead screw at an upper, forward-pointing tab.
- One M4x10mm black pan head threading screw at a lower, forward-pointing tab.
- Tug the cage rearward to disconnect it.

23) Right Side Engine-to-Tray Module Attachment
- Two M3x6mm bright pan head screws w/captive star washers.

24) Fourteen-Conductor Cable Connector
- Unplug it and free it from its hooks.

25) One M4x12mm Bright Pan Head Threading Screw
- It's at the left side, just below and behind the lower rear corner of the fan.

26) Engine Chassis
- It's free to be lifted off the paper tray module.
- Blow out the chassis w/compressed air.

27) Engine Controller PCA
- NOTE: This part needn't be removed, but it should be unfastened so the PCA and its environs can be blown out with compressed air.
- Switch rod. Disengage its rear end from the switch and move the rod aside.
- Three cable connections at the fan side of the PCA.
- Four M4x12mm bright pan head threading screws.
- Three M3x6mm bright pan head screws w/captive washers.

28) Tray 2 Top Cover
- Two M3x6mm black pan head screws.
- Four M4x10mm black pan head threading screws.

29) Tray 2 Pickup Assembly
- One two-conductor cable connection. Free the black cable from its restraints.
- Lift the unit out.
- Clean/replace rollers A/R.
- INSPECT the pickup solenoid for stickiness.

30) PCA Cover
- Two claws at the top edge.

31) PCA P/N RG5-2673
- Two cable connections.
- Two claws.
- Apply WD-40 to the pushbutton switches and actuate them many times. Blow them out w/compressed air.

32) Blow out and clean the base A/R.

33) Reassemble the tray module.


34) Reinstall the chassis on the tray module.

35) Reassemble from step '25)'.

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FEEDBACK

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HP LaserJet 4100 -- Fuser Continuity Test Points

The 4100 fuser has two heaters and two thermistors. Here's a view of the fuser's connector.

The two large pins at the right are one heater's terminals -- approx 46 ohms.

The next two large pins just to the left are the other heater's terminals -- approx. 34 ohms.

The two small pins at the lower right are one thermistor's terminals -- approx. 1.7 megohms.

The next two lower small pins just to the left are the other thermistor's terminals -- approx. 5 megohms.

- - -

The upper row of small pins is for exit sensors. The two remaining small pins are n/c.

The large pin at the lower left is chassis ground.

The large pin at the upper left is for a 'brush' that contacts the fuser's sleeve.

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FEEDBACK

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Genicom 3860 -- Main Logic PCA Removal

The Main Logic PCA is removed as an assembly with its EMI/RFI shield attached. There is no need to unfasten the PCA from the shield. All but one of the covers have to come off. Proceed as follows:

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Cover Removal

1) Ribbon Cartridge Access Cover
- Tip it up and lift it off its hinge pins.

2) Upper Rear Cover
- Tip it back and disengage the two restraint straps from their studs.
- Lift it off its hinges.

3) Main Cover
- Two M4x16mm pan head screws w/flanged spacers (i.e. the upper rear cover restraint strap studs.)
- Two ground wire spade terminals.
- Two claws at front under the ledge.
- Two claws behind where the screws w/flanged spacers were.
- Lift the cover partway off.
- One cable connection at control panel.
- Lift the cover completely off.

4) Lower Left Side Cover
- Two claws underneath.
- One claw at upper front.

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Main Logic PCA w/EMI/RFI Shield Removal

1) There's a sheet metal ground continuity plate at the lower rear. Remove it -- three M3 screws.

2) Sixteen cable connections.

3) Two M4x14mm hex head screws w/flat washers (7mm A/F hex). The screws are at the left side of the printer mechanism cavity. They're what's holding the inboard side of the PCA/Shield assembly in place.

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FEEDBACK

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Genicom 3860 -- Cover Removal

Proceed as follows:

1) Ribbon Cartridge Access Cover
- Tip it up and lift it off its hinge pins.

2) Upper Rear Cover
- Tip it back and disengage the two restraint straps from their studs.
- Lift it off its hinges.

3) Main Cover
- Two M4x16mm pan head screws w/flanged spacers (i.e. the upper rear cover restraint strap studs.)
- Two ground wire spade terminals.
- Two claws at front under the ledge.
- Two claws behind where the screws w/flanged spacers were.
- Lift the cover partway off.
- One cable connection at control panel.
- Lift the cover completely off.

4) Lower Left Side Cover
- Two claws underneath.
- One claw at upper front.

5) Lower Right Side Cover
- Same as previous.

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FEEDBACK

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Lexmark T Series -- Too Soft Fuser Wipers

There's a 'no-name' make of fuser cleaning wand out there that's worse than useless. The felt is extremely soft and limp -- there's no firmness to it whatsoever. Whenever you encounter a very soft fuser wiper, best to just throw it out. It's liable to end up like this.


Here's another view of the aftermath.


That fuser was fully overhauled in July of this year. It would still be out doing its job but for that wretched felt.

WEDNESDAY, DECEMBER 21, 2011

Addendum

Inside the felt cavity of these wands is embossed, "CC1138 MADE IN CHINA".

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FEEDBACK

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Lexmark T64X -- Fuser Teardown/Overhaul Checklist

This document is a condensation of a procedure. It can serve as a checklist once one is familiar with all the informaton in the procedure.

- - -

Proceed as follows:

1) Left Side Lamp Terminal Cover

2) Left Side Lamp Terminal

3) Lamp

4) Thermistor Cable

5) AC Spade Connector at the upper right of the top cover

6) Top Cover

7) Stripper Bar Torsion Springs

8) Exit Roller

9) Idler Gear

10) Pressure Roller Springs
- Unhook them at the front.

11) Ring Gear

12) Left Side Bearing

13) Hot Roller w/Bushings

14) Right Side Bearing

15) Input Ramp

16) Stripper Bar

17) Pressure Roller w/Bearings and Bearing Holders

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At this point, you can proceed in either of two ways.

a) Carry on with the full procedure for a thorough overhaul.

b) Abbreviate the procedure for a 'good-enough' overhaul.
- Scrape the right side lamp contact.
- Blow out the lamp contact and the sensors w/compressed air.
- Inspect the two sensors.
- Apply a couple of drops of light mineral oil to the pressure roller arms' pivot points.
- Reassemble w/new parts A/R.

- - -

18) Output Ramp

19) Pressure Roller Springs

20) Right Side Pressure Roller Arm

21) Left Side Pressure Roller Arm and Link

22) Right Side Lamp Contact Assembly

23) PCA

24) Solenoid

26) Reassemble w/new parts A/R

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Frequently Replaced Parts

Assembly, 115V Fuser, T64X: P/N 40X2592

Bearing, Hot Roll [6003Z: 17mm bore x 35mm O.D. x 10mm thick]: P/N 99A0143

Bearing, Pressure Roller [R3Z: 0.1875" bore x 0.500" O.D. x 0.196" thick]: P/N 99A1621

Pressure Roller, 28mm dia: P/N LPR-T640

Coated (Hot) Roller, 30mm dia: P/N UFR-T640

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FEEDBACK

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Lexmark T64X -- Routine Teardown/Overhaul Checklist

This document is a condensation of a procedure. It can serve as a checklist once one is familiar with all the information in the procedure.

PRELIMINARIES:

1) Auto Size Sensing; Tray Bias Roller

2) Maintenance Count

3) Page Count

4) Event Log

ORDER OF WORK:

1) Toner Cartridge

2) Paper Tray (Tray 1)

3) Redrive Cap

4) Fuser Cleaning Wand Cover

5) Fuser Cleaning Wand

6) Paper Support

7) Back Door

8) Redrive Assembly

9) Left Side Cover

10) Right Side Cover

11) MP Feeder Door/Platform

12) Fuser

13) Power Supply

14 Control Panel Cover and Window

15) Top Cover

16) System PCA Enclosure Cover

17) PTO Cover

18) Upper Deflector

19) MP Feeder Pick Roll

20) MP Feeder Lower Deflector/Elevator Flap Assembly

21) Pick Rolls

22) Inner Deflector

23) Transfer Roller

24) Charge Roller Assembly

25) Post-Transfer Paper Deck

26) Blow out Chassis. Blow out four optical sensors.

27) Printhead

28) Paper Feed Alignment Gearing and Drum Drive Gear -- inspect and clean gear teeth A/R.

29) MP Feeder Pickup Clutch -- lubricate sparingly with WD-40.

30) PTO Vertical Shaft -- pack grease around its two bearings.

31) Transfer Roller Bearings

32) Reassemble the machine back through item '13)', the power supply. Install the MP Feeder Door/Platform, the left and right side covers and the paper support.

33) Wipe the paper tray's slide ledges with WD-40. Fill it with paper and install it in the printer.

34) Install the cartridge. Set the machine aside.

35) Overhaul the fuser per the procedure.

36) Complete the reassembly of the machine.
- Fuser.
- Redrive Assembly.
- Back Door.
- Fuser Cleaning Wand.
- Fuser Cleaning Wand Cover.
- Redrive Cap.

37) Test operability.

38) Clear the error log.

39) Clear the maintenance count.

40) Remove paper from tray 1.

41) Remove the cartridge if it doesn't belong to the machine.

42) Install a bubble-pack restraint under the charge roller.

43) Tape the front of the machine shut.

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FEEDBACK

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Lexmark T65X -- Right Side Charge Rollers Arm

A T652 came in the shop with a damaged right side charge rollers arm. Here's a view of it out of the machine.

There's a bit of it missing by the electrical contact that connects to the bronze pin at the right side end of the charge rollers assembly.

I suspect that rough handling resulted in the left side end of the charge rollers assembly getting dislodged and falling. That would have made the assembly into a gravity-energized lever for snapping the right side arm's retainer.

Here's a view of an intact arm.

The arm is P/N 40X1893. If I can believe Lexmark's service manual illustration, it comes without the spring. I had a written-off T650 to take a good arm from, so I haven't actually seen a new service replacement part to be certain of how it's supplied.

Lexmark's service manual has nothing in it about replacing this part. Proceed as follows; it's not difficult to do.

1) Toner Cartridge

2) Paper Tray (Tray 1)

3) Redrive Cap

4) Fuser Cleaning Wand Cover w/Wand

5) Back Door
- Disengage the support strap from its 'inverted T' slot and pull the door off its hinge pins.

6) Lower Rear Cover w/Fuser Access Door -- T650
- Three M3x10mm black washerhead threading screws.
- Open the fuser access door -- two claws.
- Pull the cover away at your left and slide the cover toward your right. A downward-pointing hook will slide off a lip at the rear of the chassis.
- NOTE: The above-mentioned hook makes this an awkward part to get back in place. You have to exactly re-create the cover's attitude as the hook was coming off to get it back on again.

6) Lower Rear Cover w/Fuser Access Door -- T652
- Two M3x10mm washerhead threading screws.
- Two M3x6mm washerhead screws.
- Open the fuser access door -- two claws.
- Tip the cover rearward and lift it off of two hooks at the bottom.

7) Redrive Assembly
- Two M3x10mm washerhead screws.
- Two outward-hooking claws, left and right side, at about the middle.

8) Connection Access Cover
- Open it fully and its hinges can be popped free rearward.

9) Left Side Cover
- Two M3x8mm black washerhead screws in the handgrip wells.
- Two M3x10mm washerhead screws in deep wells in the side of the toner cartridge cavity.
- T650: Tug at the front lip and two upper claws and one lower claw will pop free. The cover's rear hinges come away easily.
- T652: Similar, but there are six claws, and one of them can be quite tenacious. First, pry at the angled upper front lip to free the upper two claws. The troublesome claw is located roughly 3" from the front and 3" from the bottom. You may have to reach in with a long narrow-bladed screwdriver to pry it loose.

10) Right Side Cover
- One M3x10mm washerhead screw at the rear.
- Two M3x8mm black washerhead screws in the handgrip wells.
- Two M3x10mm washerhead screws in shallow wells in the side of the toner cartridge cavity.
- T650: Tug at the front lip and two upper claws and one lower claw will pop free.
- T652: Similar, but there are six claws arrayed as on the left side cover.

11) Top Cover
- One M4x10mm pan head threading screw at the right rear.
- Four M3x10mm washerhead threading screws.
- The front edge has to be forced up past the rear edge of the upper front door. NOTE: It's a bit difficult to get this cover levered back into place at the front, but it is doable without damaging anything.

12) One Ty-Wrap at Frontward Red Wire

13) Black Charge Wire Spade Terminal at HVPS (High Voltage Power Supply)
- Disconnect the terminal and extract the wire from its restraint at the side.

14) Right Side Charge Rollers Pressure Spring
- Raise the upper front door.
- Unhook the spring at its front end.

15) Hinge/Arm-Link Pin
- One tiny e-clip.

16) Steel Cross-Member at Rear of Chassis (T652 -- not present on T650)
- Three M3x10mm washerhead threading screws.

17) Right Side Charge Rollers Arm
- NOTE: This part is removed by unfastening the upper portion of the right side vertical frame member, and prying the frame member aside until the arm can be slid off its pivot pin. (This is by no means a factory-approved procedure, but it does work and nothing breaks, even though an outrageous amount of prying is needed.)
- Five M4x10mm bright pan head threading screws. They're prominent and easily spotted.
- Pry aside the frame member.
- Raise the arm and slide it off its pivot pin.
- Transfer the spring to the new part.

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LexmarkT63X -- Routine Teardown/Overhaul Checklist

This document is a condensation of a procedure. It can serve as a checklist once one is familiar with all the information in the procedure.

PRELIMINARIES:

1) Auto Size Sensing; Tray Bias Roller

2) Maintenance Count

3) Page Count

4) Error Log

ORDER OF WORK:

1) Toner Cartridge

2) Paper Tray (Tray 1)

3) Redrive Cap

4) Fuser Cleaning Wand Cover

5) Fuser Cleaning Wand

6) Paper Support

7) Back Door

8) Redrive Assembly

9) Left Side Cover

10) Right Side Cover

11) MP Feeder Door/Platform

12) Fuser

13) Power Supply Output Connector Cover

14) Power Supply

15) Control Panel Clear Cover and Overlay

16) Cartridge Access Door w/Latchbar and Spring

17) Top Cover

18) Main Fan Grille

19) System PCA Pan Cover

20) PTO Cover

21) Upper Deflector

22) MP Feeder Pick Roll

23) MP Feeder Lower Deflector/Elevator Flap Assembly

24) Pick Rolls

25) Inner Deflector

26) White Glide

27) Transfer Roller

28) Charge Roller

29) Post-Transfer Paper Deck

30) Blow out Chassis. Blow out four optical sensors.

31) Printhead

32) Paper Feed Alignment Gearing and Drum Drive Gear -- inspect and clean gear teeth A/R.

33) MP Feeder Pickup Clutch -- lubricate sparingly with WD-40.

34) PTO Vertical Shaft -- pack grease around its two bearings.

35) Transfer and Charge Roller Bearings

36) Reassemble the machine back through item '13)', the power supply output connector cover. Install the MP Feeder Door/Platform, the left and right side covers and the paper support.

37) Wipe the paper tray's slide ledges with WD-40. Fill it with paper and install it in the printer.

38) Install the cartridge. Set the machine aside.

39) Overhaul the fuser per the procedure.

40) Complete the reassembly of the machine.
- Fuser.
- Redrive Assembly.
- Back Door.
- Fuser Cleaning Wand.
- Fuser Cleaning Wand Cover.
- Redrive Cap.

41) Test operability.

42) Clear the error log.

43) Clear the maintenance count.

44) Remove paper from tray 1.

45) Remove the cartridge if it doesn't belong to the machine.

46) Install a bubble-pack restraint under the charge roller.

47) Tape the front of the machine shut.

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FEEDBACK

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Lexmark T65X -- Auto Size Sensing

The T65X series has much the same auto size sensing functionality as did the earlier Ts, but the associated hardware has been completely redesigned, and flaky sensing operation is not as easy to test for. Here's a view of the size setting 'fingers' at the left side of a T650's tray. They're set for letter size in the photo.


Lexmark hasn't broken out a service replacement part number for the fingers, or any other tray component, so discarded trays will be your only source of such items. To remove a finger, slide the tray's backstop all the way to the rear and flip the tray upside down. Each finger has a little claw in back that limits how far it can pivot outward. Press on a finger's claw with a small screwdriver blade to free it. Once swung out, a finger can be slipped off its pivot pin. Here's a view of a finger out of a tray, showing the claw I was referring to.


In the chassis of the printer, the lever array, and the PCA with little snap-action pushbutton switches have been done away with; the tray's fingers operate directly on a switch module. Here's a view of the switch module in a T650.

(Not shown in that photo is a rectangular cover that's been removed. The cover has a single claw at its rear end that holds it in place.) The switch module can be removed and replaced directly; no dismantling of the machine is required. The module has two claws on it that hold it in place. Here's a view of a module out of a printer.


Switch Module Replacement

The P/N is 40X4472; Lexmark calls it "switch (media size) assembly". To replace one, proceed as follows:

1) Toner Cartridge

2) Paper Tray (Tray 1)

3) Lay the printer on its left side.

4) Remove the rectangular cover (one claw).

5) Disconnect the cable.

6) Switch Module
- The lower claw is accessible; the upper one isn't. Get the lower claw dislodged, and then it's possible to worry the thing out of place. There's just barely enough clearance, but it does come out and go back in. Don't connect the cable until the module is in place.

- - -

Testing
As in the earlier Ts, the Paper Size item in the Paper Menu reports the size setting being sensed, but it won't report changes made on the fly. You have to exit the Paper Size item and re-enter it to see a changed setting.

- - -

I've looked at the internal construction of the switch module, and I think these switches may prove to be far more reliable than the old snap-action pushbuttons were; the contacts are smeared with an anti-oxidant grease. I suspect that contact oxidation was what made the snap-action switches become unreliable as they aged.

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FEEDBACK

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Lexmark T650 -- Transfer Roller Bearing, Right Side

A T650 came in the shop with a shattered right side transfer roller bearing. The P/N is 40X1888. (All variations of the T65X series use the same part -- Lexmark calls it the 'right transfer roll bracket assembly'.) Here's a view of an intact bearing.

That one claw at the rear end of the part can be a bit awkward to get out and back in. Apart from that, replacing one of these is a straightforward job. You'll need a stubby No. 2 Phillips screwdriver for the screw that holds this part in place. For a T650, proceed as follows:

1) Toner Cartridge

2) Paper Tray (Tray 1)

3) Redrive Cap

4) Back Door
- Disengage the support strap from its 'inverted T' slot and pull the door off its hinge pins.

5) Connection Access Cover
- Open it fully and its hinges can be popped free rearward.


6) Lower Rear Cover w/Fuser Access Door
- Three M3x10mm black washerhead threading screws.
- Open the fuser access door -- two claws.
- Pull the cover away at your left and slide the cover toward your right. A downward-pointing hook will slide off a lip at the rear of the chassis.
- NOTE: The above-mentioned hook makes this an awkward part to get back in place. You have to exactly re-create the cover's attitude as the hook was coming off to get it back on again.


7) Left Side Cover
- Two M3x8mm black washerhead threading screws in the handgrip wells.
- Two M3x10mm washerhead threading screws in deep wells in the side of the toner cartridge cavity.
- Tug at the front lip and two upper claws and one lower claw will pop free. The cover's rear hinges come away easily.

8) System PCA Pan Cover
- One M3x6mm black pan head screw at the upper rear.
- Loosen off five M3x6mm black pan head screws.
- Slide the cover forward slightly and pull it away over the screwheads.

9) MP Feeder Platform
- Flex the slide pins' ways to free the slide pins.
- Tip the platform up to vertical and pull it off its hinge pins.

10) MP Feeder Door
- Pry the support arms to pop their pins out of their ways.
- Slide the door leftward off its hinge pins.

11) Upper Deflector
- Pull the extreme left end of the piece toward you and force the deflector to the right. It can then be unhooked at the right end.
- NOTE that reinstallation of this item is complicated by a downward-projecting spike near its left side end. You really have to flex the thing to get it to go back into place.

12) MP Feeder Pickup Roller w/Slip Rollers
- One e-clip.

13) MP Feeder Lower Deflector/Elevator Flap Assembly
- Disconnect the sensor cable at J35 on the system PCA (blue connector).
- Two M3x12mm washerhead threading screws at the right side.
- Two M3x10mm washerhead threading screws at the left side. A flashlight is helpful for locating the upper one of these two.
- Pull the item away while extracting the sensor cable.

14) Inner Deflector
- Two tabs at lower front, left and right.
- Two upward-hooking claws near the upper rear; accessible through rectangular openings.

15) Transfer Roller

16) Set the machine on its back.

17) Toner Density Sensor
- One M3x10mm washerhead threading screw from underneath.
- Just move the sensor aside.

18) Right Side Transfer Roller Bearing
- One M3x8mm washerhead threading screw.
- Pry/force up the claw at the rear of the part.

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Lexmark T63X -- Fuser Teardown/Overhaul Checklist

This document is a condensation of a procedure. It can serve as a checklist once one is familiar with all the information in the procedure.

1) Left Side Lamp Terminal Cover

2) Left Side Lamp Terminal

3) Lamp

4) Thermistor Cable

5) AC Spade Connector at the upper right of the top cover

6) Top Cover

7) Stripper Bar Torsion Springs

8) Exit Roller

9) Idler Gear

10) Pressure Roller Springs
- Unhook them at the lower front of the frame.

11) Ring Gear

12) Left Side Bearing

13) Hot Roller w/Bushings

14) Right Side Bearing

15) Input Ramp

16) Stripper Bar

17) Pressure Roller w/Bearings and Bearing Holders

- - -

At this point, you can proceed in either of two ways.

a) Carry on with the full procedure for a thorough overhaul.

b) Abbreviate the procedure for a 'good-enough' overhaul.
- Scrape the right side lamp contact.
- Blow out the lamp contact and the sensors w/compressed air.
- Apply a couple of drops of light mineral oil to the pressure roller arms' pivot points.
- Inspect the two sensors.
- Reassemble w/new parts A/R.

- - -

18) Output Ramp

19) Pressure Roller Springs

20) Right Side Pressure Roller Arm

21) Left Side Pressure Roller Arm and Link

22) Right Side Lamp Contact Assembly

23) PCA

24) Solenoid

26) Reassemble w/new parts A/R

- - -

Frequently Replaced Parts

Assembly, 115V Fuser, T630/632: P/N 56P2542 [was 56P1333]

Assembly, 115V Fuser, T634: P/N 56P2545 [was 56P1859]

Bearing, Hot Roll [6003Z: 17mm bore x 35mm O.D. x 10mm thick]: P/N 99A0143

Bearing, Pressure Roller [R3Z: 0.1875" bore x 0.500" O.D. x 0.196" thick]: P/N 99A1621

Pressure Roller: P/N 99A0158-CLT

Coated (Hot) Roller: P/N 99A2036-CLT

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Lexmark T Series -- Broken Left Side Cover Hinge Pin

Pictured below is the site of a broken-off hinge pin on a T640 left side cover. I've 'punched' the centre of it with an awl in preparation for repairing it.


This is pretty easy to repair. Proceed as follows.

1) Drill 7/64" at the centre of the break.

2) Tap the hole 6-32.

3) Cut 1/2" off the end of a long 6-32 screw to make a 'setscrew'. File the cut end smooth and square. With a mini-hacksaw, cut a slot in the cut end to accept a jeweller's screwdriver.

4) Run the setscrew into the tapped hole. Leave 3/16" of the screw protruding.

5) Apply CA adhesive to the upper part of the screw and leave it awhile to set.

Here's how it looks when it's done.

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