Lexmark X215 Paper Tray Differences

Later machines have a feature added that makes early paper trays incompatible with later chassis. An early paper tray in a later chassis will not close properly, resulting in pickup failures.

The added feature is automatic lowering and latching of the paper tray's paper platform as the tray is withdrawn.

The feature consists of a linear cam in the chassis' left side way, and a corresponding actuator attached to the left side of the tray's paper platform. When the tray is withdrawn, the cam strikes the actuator and forces the paper platform down. Owing to the cam's position, it interferes with complete closure of early trays.

There appears to be no retrofit available.

# # #

Lexmark X215 'Door Open' Message

The cover open switch is a lever-operated microswitch at the right front corner of the power supply PCA. A black plasic lever on the chassis' right side actuates it when the front door is closed.


If you're getting false 'door open' messages after having removed and reinstalled the electronics pan, it's probably because you got the switch's lever over top of the black plastic lever instead of underneath it as you were putting the electronics pan in place.


Fortunately, there's no need to take the electronics pan back out. Just remove the rear and the right side covers. The black plastic lever will be accessible. Take out the lever's screw, correct the lever's position and reassemble.

# # #

Lexmark X215 Pickup Roller Replacement

The pickup roller with its square shaft and bearings are removed and replaced as an assembly.

1) Cartridge

2) Paper Tray

3) Rear Cover
> Four M3x10mm bright washerhead threading screws. Two of them are very low down in deep wells.
> Tug the cover rearward to remove it.
> MIND the parallel connector's bails when reinstalling this cover.

4) Right Side Cover (Optional. It's not necessary to remove this cover, but with it removed, the machine won't rock when it's laid on its right side.)
> Tug the cover forcefully rearward to remove it.

5) Left Side Cover
> Disconnect the speaker.
> Tug the cover forcefully rearward to remove it.

6) Drivetrain Assembly
> NOTE the green ground wire at the upper centre screw.
> Six M3x10mm bright washerhead threading screws.
> One cable connection.

7) Electronics Pan
> Four cable connections in view at the rear.
> Two M3x10mm bright washerhead threading screws at the rear. NOTE the black ground wire at the left side screw.
> Lay the machine on its right side.
> Ten M3x10mm bright washerhead threading screws from underneath. NOTE that two of the screws are accessed through 10mm diameter holes in the pan.
> CAUTION: Two of the following seven cable connections can be transposed. They're the two smallest two-conductor connections -- CN4 and CN6. You may want to mark one of them to preclude transposing them.
> Seven cable connections.

8) Gear Support Plate at Front Left
> Three M3x10mm bright washerhead threading screws.

9) Pickup Clutch
> Pull it straight off. NOTE that it's indexed to go on only one way.

10) Pickup Roller w/Shaft
> The left side bearing has a claw. Release the claw and the bearing can be slid rightward, enabling removal of the item.

# # #

Lexmark E323 Fuser Replacement

Fuser replacement in the E323 is complicated somewhat by the need to remove the charge roller for access to the fuser. Also, the thermistor cable is strung clear across the machine underneath. The bottom pan must be removed to get at it.

1) Cartridge

2) Top Cover
> Two M3x10mm pan head threading screws.

3) Right Side Cover
> Two finger-operable claws in front.

4) Left Side Cover
> One M3x10mm pan head threading screw.
> Two claws in front.

5) Controller PCA Cover
> Four M3x6mm YZD hex washerhead screws.

6) Thermistor Cable at Controller PCA
> Two-conductor cable connection at J14. (Lexmark's service manual claims that there are two thermistors in the E323. The second thermistor allegedly connects to a 'J22'. We know of no such second thermistor.)
> Free the cable from the clamp.

7) Bottom Pan (to free the thermistor cable entirely)
> Set the printer on its back.
> One M3x6mm YZD hex washerhead screw at the left rear.
> Three M3x10mm YZD washerhead threading screws.
> Drop the pan.
> Extract the thermistor cable and temporarily reattach the bottom pan for now. You'll need to open it up again to restring the new fuser's thermistor cable.

8) Controller PCA w/Enclosure
> Thirteen cable connections. Free the cables from the enclosure.
> Three M3x6mm YZD hex washerhead screws outboard of the enclosure.
> Two M3x10mm YZD washerhead threading screws at the upper edge of the PCA.

9) Fan
> Two M3x18mm YZD hex washerhead threading screws.
> Let the fan dangle.

10) Fuser Top Cover
> Two M3x10mm bright pan head threading screws.
> Pry gently in back of the two torsion springs to free the cover.

11) White Charge Roller Clips
> Remove the clips to free the charge roller from the door-mounted levers. Let the charge roller swing over and rest behind the fuser.
> NOTE the different-coloured torsion springs; the brass-coloured spring is at the left.

12) Torsion Spring Ends
> Unhook them to relax their tension somewhat.

13) Charge Roller Pivot Retainers
> One claw at each. Pull them off.

14) Charge Roller Assembly
> It's now possible to free the left side pivot arm, and then the entire assembly.
> Note the pre-tensioned installation of the torsion springs.

15) Fuser Heater Wires
> Two spade terminals.

16) Fuser Ground Wire
> One M3x10mm YZD washerhead threading screw.

17) Fuser
> Free the thermistor cable from the cable clamp nearest the fuser.
> Two M3x10mm YZD washerhead screws.
> Two claws in front.

You'll need to remove the top cover from the replacement fuser before installing it.

# # #

Lexmark E323 Pickup Roller Replacement

The E323's pickup roller is a complete shaft/cams/roller assembly that's replaced as a unit.

The following procedure also removes the lower registration roller so it can be cleaned.

1) Cartridge

2) Top Cover
> Two M3x10mm pan head threading screws.

3) Right Side Cover
> Two finger-operable claws in front.

4) Left Side Cover
> One M3x10mm pan head threading screw.
> Two claws in front.

5) Rear Cover
> Two M3x10mm pan head threading screws.
> NOTE that the separation pad is now accessible for replacement.

6) Controller PCA Cover
> Four M3x6mm YZD hex washerhead screws.

7) Controller PCA w/Enclosure
> Fourteen cable connections. Free the cables from the enclosure. NOTE that connector J19 is unused.
> Three M3x6mm YZD hex washerhead screws outboard of the enclosure.
> Two M3x10mm YZD washerhead threading screws at the upper edge of the PCA.

8) Paper Input Chute
> One M3x6mm YZD hex washerhead screw at the ground continuity strap.
> Two M3x10mm YZD washerhead threading screws.
> Tip the chute rearward. Don't try to remove it entirely.

9) High Voltage Power Supply
> One cable connection at the top edge.
> Four M3x10mm YZD washerhead threading screws.
> Six 'bullet' contacts w/springs.

10) Main Drive Train
> Tray 2 bulkhead connector. Two claws. It lifts up out of its bracket.
> Free two cables from the cable clamp at the rear.
> Free the cabling from the cable clamp at the front.
> Four M3x10mm YZD washerhead threading screws.

11) Pickup Clutch
> One claw.

12) Pickup Roller
> Two swing-latch bearings.
> Tip the paper input chute forward a bit, and you'll be able to shift the roller shaft rightward to free its left side end.

13) Upper Registration Roller/Gate Assembly
> One swing-latch bearing.

14) Registration Idler Gear
> Slip it off its spindle.

15) Lower Registration Roller Gear
> One claw.

16) White Bearing
> Slip it out.

17) Lower Registration Roller w/Bearings
> Pry it upward and it'll pop out.

# # #

Oki 320/1 Turbo, 420/1 -- Menu Mode Unavailable

If you can't get at the Menu Mode by pressing SHIFT + MENU, it's likely because the Operator Panel Function item in the menu has been set to Limited Operation.

Load continuous forms and switch off the printer. Power on while holding SHIFT + MENU. The printer will come up in Menu Mode. Operator Panel Function is an item in the Set-Up group. Change it to Full Operation to restore complete functionality.

# # #

Label Sheet Feeding

Sheets of labels can be troublesome for pickup rollers because of their relatively slick surface on the back. Even new pickup rollers can experience traction failures on them. There is some traction force adjustability in Lexmark's autocompensator arms that may help. Here's a view of it in a T640 add-on tray.

The light spring that extends down the upper side of the autocompensator arm is a counterbalance spring. It's there to limit the pressure the pickup tires can exert when they're turning, so that multiple pickups don't occur.

Note the clip that anchors the end of the spring -- that clip's position is the adjustment. The clip in the photo is set at design centre.

For trays that feed label sheets, move the anchor clip to its uppermost/rearmost position, as in the following photo.

That minimizes the spring's counterbalancing effect, maximizing traction. (On the T640 and T650 integral trays, the clip has been deleted; there's a series of holes along the top of the arm that provide the same adjustability.)

I ran the pictured tray with ordinary paper after adjusting it for maximum traction, and had no double-feeding occur.

For label sheets, it's also wise to avoid third-party pickup rollers. From what I've seen of them, they just don't have the traction of the OEM parts -- either 40X0070 or 40X4308.

# # #

FEEDBACK

# # #

Epson DFX-5000+ Label Jam Notes

We had a machine come in that had been printing 2" x 4" tractor-fed labels. A label was stuck to the face of the ribbon mask, and to the rear suface of the spring-loaded tension plate below the platen. Following are a few notes on how the clean-up went.

a) Ribbon Mask:

The ribbon mask is attached to the printhead by two studs with screwdriver slots in their ends. The one at the left had a broken slot. When I got the complete printhead out and looked at the ribbon mask's attachment, it appeared that the left side stud had been cemented in place at the factory. Why they would do that is beyond me, but it's something to be mindful of. If you go to remove a ribbon mask stud and it can't be loosened easily, stop; you'll just break the screwdriver slot if you keep torquing it harder. Take the whole printhead off and see what you're up against.

Wetting the stuck label with Varsol was helpful for getting it off.

A good feature of the printhead/carriage is that the printhead is self-positioning as it's put back on the carriage. Removing and reinstalling the printhead won't alter the printhead/platen gap adjustment.

b) Tension Plate:

It would have been nice to have removed this item to get the label off of it, but it looked like something I might not be able to get back in without tearing down the whole machine.

I took a sheet of paper towel, folded it in four, dipped it in Varsol and placed it behind the tension plate where the label was stuck to it. After about half-an-hour, the label came away easily. Varsol is a fairly benign solvent, so it did no harm to the adjacent plastic parts.

All-in-all, a good outcome. That Varsol soak saved a lot of work and gave a good result.

(From what I've observed, not all label adhesives are the same. In a case where Varsol is ineffective, try methyl hydrate. It's also relatively benign and won't harm plastic.)

# # #

HP LJ 4350tn -- Paper Feed Assembly Access

1) Cartridge

2) Tray 2

3) Back Door Open

4) Top Rear Cover
> Pull it straight up.

5) Right Side Rear Cover
> Pull it straight back.

6) Cartridge Engagement Arm
> Disconnect it from the toner cartridge access door.

7) Top Cover Assembly
> Four M3x8mm washerhead screws.
> Lift the cover about an inch.
> Control panel cable connection.
> Lift the cover away entirely.

8) Formatter Cage Door
> Open it and lift to remove.

9) Right Side Cover
> One large claw at upper rear.
> One claw at arrowhead in front behind tray 1 door.
> One claw at arrowhead in front just below tray 1 door.
> MIND THE SWITCH LINK'S ENGAGEMENT when reinstalling this cover.

10) Left Side Cover
> One claw at upper centre.
> One claw at arrowhead in front behind tray 1 door.

11) Tray 1 Door
> Spread the platform ways to separate the door from the platform. The door slides rightward off its hinge pins.

12) Tray 1 Platform w/Torsion Spring
> Free the upper end of the torsion spring. Lower the platform.
> Tug on the paper-out sensor's cowl to free it.
> Lower the platform to where it will slip off its left side hinge pin.

13) Wire Bail Over Fan
> Pry it free of its restraint hooks at its rear.

14) Door-Open Switch Cable Connection at J95
> Free the two-conductor cable from its trough. You may have to deal with some cable entanglement.

15) Front Right Side Cover w/Cover-Open Switch
> Three M3x12mm washerhead screws.
> One claw near the right side end of the envelope feeder slot.
> There's one stiff downward-gripping claw low down in back, accessible through a rectangular opening in the steel frame. Pry it upwards to free it.

16) Tray 1 Pickup Solenoid Cable Connection at J79
> Free the two-conductor cable from its trough. You may have to deal with some cable entanglement.

17) Tray 1 Pickup Assembly
> Envelope feeder slot cover.
> Paper-out sensor cable connection at left side.
> Two M3x8mm washerhead screws at the left side.
> Two M4x16mm pan head threading screws, left and right, low down in deep wells.
> Two M4x10mm pan head threading screws, left and right, near the ends of the envelope feeder slot.
> The item is free to come away. Mind the solenoid's cable as you remove it.

18) Paper Feed Clutch Cable Connection at J89
> Free the two-conductor cable from its trough. You may have to deal with some cable entanglement.
> Open three cable clamps.
> Pull the cable through the rectangular grommet.

19) Paper Feed Assembly
> One M3x8mm washerhead screw at its left side end.
> Two M4x10mm pan head threading screws at its upper mounting holes.

# # #

HP LJ 4350tn -- Tray 1 Pickup Assembly Removal

1) Cartridge

2) Tray 2

3) Back Door Open

4) Top Rear Cover
> Pull it straight up.

5) Right Side Rear Cover
> Pull it straight back.

6) Cartridge Engagement Arm
> Disconnect it from the toner cartridge access door.

7) Top Cover Assembly
> Four M3x8mm washerhead screws.
> Lift the cover about an inch.
> Control panel cable connection.
> Lift the cover away entirely.

8) Formatter Cage Door
> Open it and lift to remove.

9) Right Side Cover
> One large claw at upper rear.
> One claw at arrowhead in front behind tray 1 door.
> One claw at arrowhead in front just below tray 1 door.
> MIND THE SWITCH LINK'S ENGAGEMENT when reinstalling this cover.

10) Left Side Cover
> One claw at upper centre.
> One claw at arrowhead in front behind tray 1 door.

11) Tray 1 Door
> Spread the platform ways to separate the door from the platform. The door slides rightward off its hinge pins.

12) Tray 1 Platform w/Torsion Spring
> Free the upper end of the torsion spring. Lower the platform.
> Tug on the paper-out sensor's cowl to free it.
> Lower the platform to where it will slip off its left side hinge pin.

13) Wire Bail Over Fan
> Pry it free of its restraint hooks at its rear.

14) Door-Open Switch Cable Connection at J95
> Free the two-conductor cable from its trough. You may have to deal with some cable entanglement.

15) Front Right Side Cover w/Cover-Open Switch
> Three M3x12mm washerhead screws.
> One claw near the right side end of the envelope feeder slot.
> There's one stiff downward-gripping claw low down in back, accessible through a rectangular opening in the steel frame. Pry it upwards to free it.

16) Tray 1 Pickup Solenoid Cable Connection at J79
> Free the two-conductor cable from its trough. You may have to deal with some cable entanglement.

17) Tray 1 Pickup Assembly
> Envelope feeder slot cover.
> Paper-out sensor cable connection at left side.
> Two M3x8mm washerhead screws at the left side.
> Two M4x16mm pan head threading screws, left and right, low down in deep wells.
> Two M4x10mm pan head threading screws, left and right, near the ends of the envelope feeder slot.
> The item is free to come away. Mind the solenoid's cable as you remove it.

# # #

HP LJ 4350tn -- DC Controller PCA Access

The DC Controller PCA includes a hard-wired paddle PCA for the formatter connection. The paddle PCA is permanently connected to the DC Controller by a flat cable and two wires. The combination makes for a lot of fiddling about with cabling to replace a DC Controller. Take great care not to damage the broad flat cable.

1) Back Door Open

2) Top Rear Cover
> Pull it straight up.

3) Right Side Rear Cover
> Pull it straight back.

4) Cartridge Engagement Arm
> Disconnect it from the toner cartridge access door.

5) Top Cover Assembly
> Four M3x8mm washerhead screws.
> Lift the cover about an inch.
> Control panel cable connection.
> Lift the cover away entirely.

6) Formatter Cage Door
> Open it and lift to remove.

7) Right Side Cover
> One large claw at upper rear.
> One claw at arrowhead in front behind tray 1 door.
> One claw at arrowhead in front just below tray 1 door.
> MIND THE SWITCH LINK'S ENGAGEMENT when reinstalling this cover.

8) Formatter Cage
> Two M3x6mm bright washerhead screws at the rear.
> Pull it back to disconnect/remove it.

9) Formatter Connector Paddle PCA
> Remove two M3x6mm shoulder screws.

10) DC Controller PCA
> NOTE that connector locations J76 and J94 are not used.
> Two flat cables.
> Power supply cable -- squeeze the latch to disconnect it.
> Twenty remaining cable connections.
> Free the cabling from the trough A/R to free the blue and yellow wires going to the paddle PCA.
> Free the paddle PCA's flat cable from its trough.
> You may have to disconnect the Tray 2 size sensor's cable at the sensor's switch-block to fully free the paddle PCA's wiring. CAUTION: It's very easy to dislodge the switch-block when you're reconnecting the cable.
> Two M3x8mm washerhead screws.

# # #

Hogwash

I had occasion recently to look up the fatal alarm indications in Fujitsu's DL6400/6600 maintenance manual; found them easily enough. On page 3-7 there's Table 3.5 - Fatal error alarm list. The table gives the names of the thirteen possible errors, and a brief description of each. The LED display codes are on Table 3.6 on the following page.

The alarm list table has a column titled "Recovery method". The first entry in that column, for the Power Alarm, reads "+40V supply has dropped". [?!]

Excuse me, but that's not a 'recovery method'. Of the thirteen alarms, ranging from 'left end sensor' to 'cut sheet feeder motor', eleven of them effectively indicate that "+40V supply has dropped" is the 'recovery method'. Needless to say, that column of the table is utter hogwash; beneath contempt.

I don't go rotten-cherry picking to find this stuff, and that's not an isolated instance. It's typical. By and large, the service documentation and 'training' material in this industry is a load of rubbish. That's across the board; all manufacturers.

And there's no 'solution'. People who can publish things like the 'recovery method' column in the Fujitsu alarms table are not reachable. They don't know any better and they don't give a bleep. They're locked into their witless orthodoxy, and they're not coming out for a look at the real world. You may as well talk to a cat or a potted plant as try to draw their attention to the fact that what they're producing is worthless dross, and they need to give what they're doing a rethink.

All I can say in closing is reader beware.

# # #

Fujitsu DL6400/6600 -- Fatal Error Alarms

The DL6400/6600 reports a fatal error by flashing its PAPER OUT LED, and turning on one or two FONT LEDs. There are thirteen possible alarm conditions, but only twelve alarm indications. (A ROM checksum failure doesn't produce an alarm indication.) Following are the alarm names, a brief description of each and, in square brackets, their corresponding FONT LED indicator(s). (This information is directly from Fujitsu's service manual; I haven't verified its accuracy.)

1) Power. The +40V power supply's output is low. [COUR 10]

2) Left End. The Left End Sensor (LES) failed to detect carriage arrival at the left end of its travel. [PRESTG 12] (See this post for more on this one.)

3) Overload. The +40V power supply is overloaded. [COMPRESS 17]

4) RAM. A read or write error has been detected. [BOLD PS]

5) ROM. A ROM checksum error has been detected. [Apparently, this condition does not produce an alarm indication. The service manual is unclear about what the error indication is. It says, "The program enters an infinite loop." Your guess is as good as mine as to what that looks like.]

6) FAN. The fan is inoperative. [N. SANS PS]

7) HEAD. There's a fault in a printhead driver circuit. [DRAFT 10]

8) SP Motor. A space motor (carriage motor) fault has been detected. [DRAFT 12]

9) LF Motor. A line feed motor fault has been detected. [MENU FONT]

10) GAP. There's a fault in the automatic gapping mechanism. [COUR 10 + COMPRESS 17]

11) Ribbon Motor. A ribbon motor fault has been detected. [COUR 10 + BOLD PS]

12) Jam Lever. The jam lever is open. [COUR 10 + TIME PS]

13) CSF Motor. A Cut Sheet Feeder motor fault has been detected. [COUR 10 + N. SANS PS]

# # #

Lexmark 931 through 935 Errors

Errors 931 through 935 are all printhead (laser/scanner) faults. Printhead unit replacement is the only solution. No service parts are available for the printheads.

Replacement printheads are costly, and what you get as a replacement part is likely to be a unit salvaged from an out-of-service printer, not a new unit from the factory.

On balance, when a T-Series printer starts getting printhead errors, you're well advised to write the machine off and replace it. It's likely to become a costly headache if you choose to repair it.

# # #

Fujitsu DL6400/6600 -- Setting Top of Form (TOF)

For fine incremental forward paper motion, hold ONLINE and press LF/FF.

For fine incremental reverse paper motion, hold ONLINE and press TEAR OFF.

To save your TOF position once you're satisfied with it, press ONLINE and LOAD both together.

# # #

Fujitsu DL6400/6600 -- Left End Alarm

Symptom: The PAPER OUT LED is flashing. The PRESTG 12 LED is on solid. The machine is inoperative.

Meaning: The above is a "left end alarm". The Left End Sensor (LES) failed to detect carriage arrival at the left end of its travel during the POST routine.

Possible cause: The cover interlock switch at the right front corner of the chassis isn't making. A brief explanation is in order.

The DL6400/6600 has two access cover interlocks:

a) On the upper edge of the control panel, there is a Hall-effect switch that's triggered by a permanent magnet embedded in the access cover. That device's output is a logic signal that merely informs the controller of the access cover's open/closed status.

b) At the upper right front corner of the chassis, there is a microswitch that's physically actuated by a plunger on the access cover. That switch is a safety feature. It disables the carriage drive circuitry when the cover is open. If the switch fails to make, the effect on the printer is loss of carriage motion. Hence the carriage can't get to its home position. Hence the machine reports a "left end alarm".

The microswitch is actuated indirectly via a spring-loaded pivoting paddle. In the case I came across, the actuator had gotten swung backwards and hung up on its bracket so it couldn't reach the switch. It just needed to be forced back into its correct at-rest position so it could operate as it should.

So, anytime you see a "left end alarm" on a DL6400/6600, examine the interlock switch first.

# # #

Fujitsu DL6400/6600 -- Fan Replacement

The following is for replacement of the main fan that's in the right side vertical chassis member. DL6600s have an additional fan for cooling the power supply. Access to it is gained the same way.

- - -

1) Access Cover

2) Control Panel
> Three downward-gripping claws at its upper rear.
> One cable connection.

3) Top Cover
> Two M4x10mm bright pan head screws w/captive washers at the back.
> Tip the cover up at the rear and pull it away. MIND THE CONTROL PANEL CABLE as you do this.

4) Mechanism Tilted Up
> The mechanism is not fastened at the rear. It can be tipped up and propped in position for access to the fan. There should be a prop rod held by two clips at the right side of the chassis pan.
The prop anchor hole is at the rear, just left of the Interface PCA. If the rod is missing, use a suitable screwdriver for a prop.

5) Fan
> Cable connection 'CNFAN'.
> Two M3x30mm YZD pan head screws w/captive washers.
> Air flow direction is outward.

# # #

Lexmark T640 -- Developer Drive Access/Overhaul

A machine that's had a serious toner-fouling incident will likely need to have its developer drive assembly removed, cleaned, lubricated and reinstalled. Following is the access procedure and the teardown/overhaul procedure specific to a T640. All prior 'S' and 'T' series machines are very similar. Machines with separate engine-controller/formatter architectures won't confront you with a mass of cables to be unplugged as the T640 does.

- - -

1) Left Side Cover
> Two finger-operable claws at the front. Swing it open far enough and its upper hinge will pop apart harmlessly for removal.

2) System PCA Enclosure Cover
> Loosen off six M3x6mm pan head screws.
> Slide the cover forward slightly and pull it away over the screw heads.

3) System PCA w/Enclosure
> Twenty or twenty-one cable connections, depending on model.
> There may be a ty-wrap to be cut on one of the printhead cables.
> Free the cabling from the enclosure's cable openings.
> One M3x15mm hex washerhead screw at the PCA's upper rear corner.
> Three M3x10mm washerhead threading screws. They're near the PCA's three other corners.
> The item is free to come away from the chassis.

NOTE: Before proceeding, observe the interaction of the developer drive assembly's pivoting cartridge engagement lever, and the plastic lever that's linked to the access door's hinge. Note that the engagement lever is inboard of the plastic lever.

4) Developer Drive Assembly
> One M3x28mm pan head screw at the lowermost position.
> Two M3x8mm pan head threading screws.
> The item is free to come away. NOTE that there is a loose drive coupling hub, along with a clip-fit drive coupler, between the developer drive and the main drive. NOTE their relationship.

- - -

Proceed as follows to dismantle the developer drive assembly:

1) Loose Drive Coupling Hub

2) Clip-Fit Drive Coupler

3) Lever Return Spring

4) Lever
> One e-clip.
> Withdraw the pivot pin upward.

5) Triaxial Self-Aligning Coupler
> One e-clip.
> One flat washer.
> Coupler body.
> Spring.
> Gear w/drive spline.

6) Large Idler Gear
> One e-clip.

The remaining gear is a snap-fit item that's best not removed.

Clean all components with Varsol in a parts washer.

Lubricate the gear spindles with WD-40 on reassembly.

Lubricate the coupler's flat washer and e-clip area with light mineral oil. Do not use grease anywhere.

# # #

Lexmark T640 System PCA Access

The T640 has its engine control and formatter functions combined on a single PCA, the System PCA. Proceed as follows to remove it.

1) Left Side Cover
> Two finger-operable claws at the front. Swing it open far enough and its upper hinge will pop apart harmlessly for removal.

2) System PCA Enclosure Cover
> Loosen off six M3x6mm pan head screws.
> Slide the cover forward slightly and pull it away over the screw heads.

3) System PCA w/Enclosure
> Twenty or twenty-one cable connections, depending on model.
> There may be a ty-wrap to be cut on one of the printhead cables.
> Free the cabling from the enclosure's cable openings.
> One M3x15mm hex washerhead screw at the PCA's upper rear corner.
> Three M3x10mm washerhead threading screws. They're near the PCA's three other corners.
> The item is free to come away from the chassis.

4) Option Slot(s) PCA (aka Interconnect PCA)
> Two M3x6mm pan head screws.

5) System PCA
> Five M3x6mm pan head screws: two at the parallel interface connector; one at the USB connector; two through the System PCA.
> NOTE: At reassembly, don't tighten the two screws through the System PCA until the three interface connector screws are in place and tight.

# # #

Lexmark Tray Bias Roller

Just inside the Tray 1 cavity, at the right side, there's a roller mounted in a spring-loaded arm; that's the Tray Bias Roller. It keeps Tray 1 shoved (biased) leftward to align it with the chassis and to assure reliable operation of the auto size sensing feature. It also serves as a detent pawl to hold the tray in its closed position. The rollers occasionally acquire a flat spot and need to be replaced. Here's a view of a flat-spotted roller, with a new roller to its right. (You have to transfer the spring to the new part.)



Beginning with the Optra S and continuing on through the T630, the service replacement part was P/N 99A0026. On the T640, the P/N has changed to 40X0213. There is no dimensional/functional difference between the two parts that I can see, but P/N 40X0213 is considerably less expensive than P/N 99A0026. (This is not the first time I've seen a gross inconsistency in Lexmark's parts pricing.)

The thing to do, obviously, is to order and stock only the T640 part, P/N 40X0213.

- - -

To replace one of these, remove the cartridge, tray 1, the redrive assembly and the right side cover. The front end of the spring is hooked onto an anchor post very near the front of the printer. Here's a view of that.

Get a firm grip on the straight section of the spring with long-nose pliers and you can unhook the spring from its anchor post. Note the spring's path through the chassis member as you extract it. Transfer the spring to the new part, thread the spring back through and anchor it. Confirm that the roller arm's pivot-point is correctly seated before buttoning up the printer.

# # #

FEEDBACK

# # #

HP LJ P3005 -- Formatter Access

1) Right Side Cover
> Force it rearward a bit to free it.

2) Formatter Cage Door
> Tug it open and lift to remove it.

3) Formatter PCA
> Three cable connections.
> Six M3x8mm pan head screws w/captive washers.
> The PCA is free to come out.
> NOTE that there's a lithium button cell on the board. Mind where you set the board down so as not to short it.

# # #

HP LJ P3005 -- Engine Test

The engine test pushbutton is well hidden. Remove the right side cover by forcing it rearward. About 1 1/2" below the bottom-front corner of the fan grille there's a small round hole. Poke in there to operate the switch.

Press and release for a single print. If you hold down the switch, the test will print pages continuously until the switch is released.

The test print is horizontal lines.

# # #

Lexmark T-Series High Voltage Power Supply (HVPS) Access

The following procedure is specifically for the T63x machines, but all of the T models prior to the T650 (and even the old Optra S) are very similar. On the T650, the HVPS is directly behind the right side cover; it's much easier to get at.

Here's a view of the HVPS in a T642. The T64X HVPS has been failure-prone (917 errors).

Proceed as follows:

1) Toner Cartridge

2) Paper Tray (Tray 1)

3) Redrive Cap
- Lift it up at its right side end to remove it.

4) Back Door
- Open it to about 30º from vertical and you can pull it away off its hinges.

5) Redrive Assembly
- Two M4x8mm pan head thread-rolling screws.
- Two outward-hooking claws, left and right side, high up.

6) Right Side Cover
- One M3.5x10mm pan head threading screw from high up inside the redrive cavity.
- One M3.5x10mm pan head threading screw from inside the cartridge cavity.
- One claw at the front just above the MP Feeder.

7) MP Feeder Door/Platform
- Open it to about a 45º angle and it can be pulled off its flatted hinge pins.

8) 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.

9) MP Feeder Pick Roll
- One claw. Don't over-deflect it. It's easily snapped off. In the event of a claw snapping off, a small (3") ty-wrap works fine as a retainer.

10) MP Feeder Lower Deflector/Elevator Flap Assembly
- NOTE 1: This item is easily removed, but can be awkward to get back in place. Before proceeding, note carefully the relationship between the MP Feeder’s pickup cycle cam, and the cam follower that’s integral with the Elevator Flap. Keeping that relationship in mind at reassembly will be helpful.
- NOTE 2: At reinstallation, wipe off the face of the separation pad with methyl hydrate prior to putting the pickup roller back on its shaft.
- One M3.5x8mm pan head threading screw at the solenoid's base.
- Two M3.5x12mm pan head threading screws at the right side.
- Two M3.5x8mm pan head threading screws at the left side.
- Force the flap to open fully.
- Remove the spring.
- Dislodge the sensor cable and the sensor.

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

12) HVPS
- One spade terminal at the right rear. It can take a fair bit of force to get it off with pliers.
- One cable connection at the left front.
- Two M3x6mm pan head screws at the front.
- Pry up the PCA slightly at its right rear corner to free it from a small stud, and pull it leftward to free it.

# # #

FEEDBACK

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HP LJ P2015 Formatter Access

There's not much to it.

1) Tray 2 out.

2) Front Door open.

3) Left side Cover
> Pry near the top and bottom at the rear edge. The rear edge will pop free and you can unhook the front edge.

4) Formatter PCA
> Five cable connections.
> Four M3x6mm black washerhead screws.

# # #

Oki PM 3410 -- Paper Unloads Instead of Parking

Symptom: Paper is in position, loaded from a bottom push tractor-feed unit. The user presses 'PARK' and the paper unloads completely instead of parking.

The bottom feed paper-out sensor is likely hung up on a paper shard; the machine can't tell when the paper has gone past the sensor. A good blow-out of the chassis with compressed air will often clear it up. If it doesn't, you'll have to make a visual confirmation that the sensor is toggling normally and is undamaged. If all appears to be ok mechanically, a check of the sensor's electronic signal output is in order (often much easier said than done). Failure of sensors' electronics is extremely rare, though.

Generally, whenever you encounter this symptom from whichever paper path, it's a binding paper-out sensor that's causing it.

# # #

Lexmark Autocompensator Retraction Bellcrank (aka 'Spring Arm Bellcrank')

The bellcrank is available as a service replacement part, P/N 56P1228. Proceed as follows to replace a broken one.

1) Tray 1 and Cartridge out. Set the machine on its back.

2) One E-Clip at the right side end of the autocompensator's pivot rod.

3) One M3x6mm pan head screw at the rear of the autocompensator's frame.

4) Unhook cabling A/R.

5) Slide the autocompensator assembly rightward to free the left side end of the rod. The assembly can then come away from the printer's chassis.

6) Bellcrank
- Force the broken part off the the end of the rod with a pair of Channellocks.
- NOTE that the protruding spring-hook portion of the bellcrank must go to the right.
- The bellcrank is a snap-fit onto the shallow groove in the rod. It must end up as far to the left on the rod as the flat portion of the rod will allow it to go.
- A 5/16" nutdriver can be used as a 'punch' to get the bellcrank started onto the rod with a light hammer blow.

7) Attach the spring to the new bellcrank and reinstall the autocompensator assembly. Here's a view of the bellcrank fully installed.



Springs

There are four different springs used with the bellcrank, depending on tray capacity and whether it's an integral tray or an add-on.

• 250-Sheet Add-On Spring P/N 99A1929.
• 250-Sheet Integral Spring P/N 99A1927.
• 500-Sheet Add-On Spring P/N 99A1928.
• 500-Sheet Integral Spring P/N 99A1930.

# # #

FEEDBACK

# # #

HP LJ 2200 -- False Paper Out

Symptom: Flashing amber LED. Paper in Tray 2. Manually operating the paper-out sensor's toggle makes the machine come ready.

It's possible for the paper level indicator lever to get dislodged and interfere with the paper platform's upward travel. Then, even though there's paper in the tray, the platform can't raise it high enough to actuate the paper-out sensor's toggle.

Simplest solution is to delete the indicator lever. To gain access, remove the front of the tray by prying two tabs out of their notches. ( The tabs are on top at the left and right sides, about 1 1/2" back from the front face of the tray.) The lever can be manoeuvred out frontward once the front of the tray is off.

# # #

Oki 393 Tractor Phasing

Tractor phasing in the Oki 393 is correct when the following conditions obtain:

a) The timing marks (holes) in the two gears are directly facing one another.

b) The timing marks on the two large round sprockets are facing rearward.

c) The timing marks on the tractor-drive sprockets are facing forward.

Any time you have the tractors dismantled, take the opportunity to dab the sprockets' timing marks with Liquid Paper. They'll be a lot easier to see when they're in the machine.

Verify the tractor phasing by loading one sheet of tractor-feed paper, and hand cranking it toward the large round sprockets. The pins on the large sprockets should mesh perfectly with the paper coming from the tractors.

# # #

Oki 393 Menu Mode

The Oki 393's control panel has no sub-legends for the menu mode key functions. Following is a summary of the 393's menu mode functionality (continuous forms loaded is assumed):

To enter menu mode from power off:

• Press and hold 'QUIET' while powering on.

To enter menu mode while powered on:

• Deselect.
• Press 'QUIET'.

The key functions while in menu mode are:

• List All -- 'QUIET'
• Group -- 'LINE FEED'
• Item -- 'FORM FEED'
• Set -- 'TOP OF FORM'
• Exit -- 'SELECT'

# # #

Terminology -- Laser/Scanner Assembly vs. Printhead

Since early days, we've been accustomed to the term 'laser/scanner assembly' (often just 'scanner') for the item in a printer that provides the laser beam scanning and modulation to write a latent electrostatic image on a drum. But with the advent of so many multifunction machines with document scanners on them, confusion begins to creep in when one says 'scanner'.

That points up the wisdom of Lexmark's choice of the term 'printhead' for laser/scanner assembly. The term is unambiguous, and can't be miscontrued as having anything to do with a document scanner.

So, throughout the posts here, I'll use the term 'printhead' for the laser/scanner assembly in any make of printer.

# # #

HP LJ 2420 Printhead Access

1) Cartridge

2) Tray 2

3) Rear Cover/Door Assembly
> Pull the rear door fully open.
> Two M4x10mm pan head threading screws.
> Two claws within the tray 2 cavity.

4) Formatter Cage Cover
> Force it rearward a bit to free it.

5) Left Side Cover
> Two M3x8mm bright washerhead screws in the handgrip cavity.
> One forward-hooking claw inboard at the upper rear. It’s high up in a rectangular well.
> Two downward-hooking claws at the underside.
> There are two concealed, inaccessible, downward-hooking claws at the top. Tug away at the rear and pry at the top to force those two claws to unhook.

6) Mains Receptacle Bezel
> Treat as if hinged at its outboard long edge.
> There’s a single downward-hooking claw about 3 3/8" below its top edge. If the item is stubborn, slide a thin tool in behind it about 4" below its top edge and move the tool upward. You’ll unhook the claw.

7) Top Right Rear Corner Cover
> One M3x6mm black washerhead screw at the rear.

8) Top Cover
> Four M3x6mm black washerhead screws.
> NOTE that at reinstallation, the front edge of this cover must be hooked in place before lowering it into place.

9) Black Plastic Air Duct Cover P/N RC1-4128
> One claw.

10) Printhead
> Two cable connections.
> Four M3x8mm bright washerhead screws.

To open the printhead for cleaning, there's one M3x8mm pan head threading screw on top and four tabs. With the top cover off the printhead, there's a safety-interlock shutter that's free to fall out.

# # #

Lexmark 924 Error

'924 Service' is an open fuser thermistor error. Replace the thermistor.

On later models, with the fuser out of the machine, the thermistor is readily accessible; no disassembly of the fuser is required. The Optra S and some early 'T's needed the fuser's top cover to be removed in order to replace the thermistor.

The thermistor is at the upper front of the fuser, near the left side end. On later models it's held in place with a single M3x10mm pan head screw w/captive washers. It has a two-conductor cable that runs back to the fuser's PCA. Early machines had pushnuts for cable restraints -- the pushnuts can be coaxed off by using a scriber point as a fine prybar. Later machines have open hook-restraints.

A good thermistor exhibits a room temperature resistance reading of approximately 400 kohms. The resistance falls with rising temperature (negative temperature coefficient). You can see the effect on an ohmmeter just from the warmth of your hand. The thermistor's resistance provides the engine controller's logic with an analogue of fuser temperature. An open (infinite resistance) thermistor renders the fuser inoperative; hence the fatal 924 error very early on in the printer's POST.

# # #

Lexmark T63X Routine Teardown/Overhaul

[NOTE: There's a condensed, 'checklist' version of this document here.]

Following is our standard procedure for an in-shop overhaul of a T63X series printer. The procedure assumes a machine that's basically in working order, but in need of a teardown, a thorough cleaning and a fuser overhaul.

The developer drive, main drive and the paper alignment assembly are left undisturbed; they normally don't require attention. In cases of severe toner spillage, those items do need to be removed and cleaned/overhauled.

PRELIMINARIES:

1) Auto Size Sensing; Tray Bias Roller
- See this post for information on checking and servicing the auto size sensing feature.
- Inspect the tray bias roller that's just inside the tray cavity at the right side. The roller must be free spinning and have no flat spots. Flat-spotted rollers must be replaced. The part is accessible once the right side cover has been removed. See this post for more information.

2) Maintenance Count
- To view the accumulated page count since the last time anyone cleared it, press and hold the 'Select' and 'Return' keys while powering on. That invokes the CONFIG MENU where you can check and clear the maintenance count. Clear the maintenance count after you're done testing the completed machine.

3) Page Count
- The page count and the permanent page count can both be found in the DIAGNOSTICS menu within PRINTER SETUP. To invoke the DIAGNOSTICS menu, press and hold the 'Go' and the 'Return' keys while powering on.

4) Error Log
- The error log is an item in the DIAGNOSTICS menu.
- When there are items in the error log, note what they are. They're usually just paper jams and the like. The presence of printhead errors calls for printhead replacement. The machine is likely to be written off because of the high cost of the part.
- Clear the error log after you're done testing the completed machine.


ORDER OF WORK:

1) Toner Cartridge
- Machines seldom come into the shop with a toner cartridge. When they do, be sure to note it and label the cartridge so it goes out with the printer. If the cartridge has a defect, it should still go out with the printer, but clearly labelled that it's defective.

2) Paper Tray (Tray 1)
- Check that the backstop is linked to the size sensing key and is operable. When set for letter size paper, the two lower sensing fingers should protrude, the upper finger should be retracted.
- The four black ramps in front must be clean. Trays that have been used for sheets of labels are liable to have label adhesive muck fouling the ramps. Clean A/R with Varsol and/or methyl hydrate.
- Examine the pass-thru slot at the front of the tray for stuck labels or damage.

3) Redrive Cap
- Lift it up at its right side end to remove it.
- One or both of the two prongs that secure this part is/are often broken. P/N is 99A2074.

4) Fuser Cleaning Wand Cover

5) Fuser Cleaning Wand
- NOTE that the felt strip is removeable and reversible.
- In place of a cleaning wand, there is often an item that's just a cover for the cleaning wand cavity. It will have a small handle at its centre. The handle goes to the rear.

6) Paper Support
- Tip it up and pull it off its hinges.

7) Back Door
- Open it to about 30º from vertical and you can pull it away off its hinges.
- Check that the duplexing deflector's torsion spring is in place and correctly hooked at its ends. The deflector must pivot freely, and return smartly to its at-rest position when released.

8) Redrive Assembly
- Two M4x8mm pan head thread-rolling screws.
- Two outward-hooking claws, left and right side, high up.
- Check that the output diverter is in place in its bearings and spring-loaded.
- Check that the duplex diverter push-rod is properly fastened and free moving. If the little fasteners/glides show any sign of being loose, apply a drop of CA adhesive to cement them in place permanently.

9) Left Side Cover
- Two finger-operable claws at the front. Swing it open far enough and its upper hinge will pop apart harmlessly for removal.

10) Right Side Cover
- One M3.5x10mm pan head threading screw from high up inside the redrive cavity.
- One M3.5x10mm pan head threading screw from inside the cartridge cavity.
- One claw at the front just above the MP Feeder.

11) MP Feeder Door/Platform
- Open it to about a 45º angle and it can be pulled off its flatted hinge pins.
- If this item is really filthy, it can be easily dismantled for washing. There are just the three obvious M3x8mm pan head threading screws holding it together.

12) Fuser
- Power cable in-line connection.
- Signal cable connection at PCA.
- Two M4x8mm pan head screws w/captive washers.

13) Power Supply Output Connector Cover
- One M3x6mm pan head screw.

14) Power Supply
- Two M3x6mm pan head screws at the rear.
- Slide the unit rightward far enough that you have access to the output cable connection.
- Output cable connection.
- Slide the unit rightward far enough that you have access to the fuser power cable connection.
- Fuser power cable connection.
- Slide the unit rightward fully out.

15) Control Panel Clear Cover and Overlay
- Pry gently at its upper edge.

16) Cartridge Access Door w/Latchbar and Spring
- One M3.5x10mm pan head threading screw.
- Two M3.5x10mm pan head threading screws w/captive washer.

17) Top Cover
- NOTE: At the upper right rear corner there is a screw w/captive washer that need not be removed. The tab it’s associated with is not actually fastened in place by the screw.
- One M3.5x8mm threading screw at the right side -- it’s a bit tucked away below the rearward curve of the cover.
- Three M3.5x12mm threading screws w/captive washer.

18) Main Fan Grille
- NOTE: This part has two small locating studs underneath that are easily broken if the part is levered off crookedly. Pry the grille up gently to avoid breaking the studs.
- Wide end goes over fan; narrow end forward.

19) System PCA Pan Cover
- Loosen off six M3x6mm pan head screws.
- Slide the cover upward slightly and pull it away over the screwheads.

20) PTO Cover
- One M3.5x8mm pan head threading screw.

21) 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.
- Check for any accumulation of label adhesive muck on the item's undersurface. Clean with Varsol and/or methyl hydrate A/R.
- 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.

22) MP Feeder Pick Roll
- One claw. Don't over-deflect it. It's easily snapped off. In the event of a claw snapping off, a small (3") ty-wrap works fine as a retainer.
- Blow off the paper dust and clean the tire with lacquer thinner.

23) MP Feeder Lower Deflector/Elevator Flap Assembly
- NOTE 1: This item is easily removed, but can be awkward to get back in place. Before proceeding, note carefully the relationship between the MP Feeder’s pickup cycle cam, and the cam follower that’s integral with the Elevator Flap. Keeping that relationship in mind at reassembly will be helpful.
- NOTE 2: At reinstallation, wipe off the face of the separation pad with methyl hydrate prior to putting the pickup roller back on its shaft.
- One M3.5x8mm pan head threading screw at the solenoid's base.
- Two M3.5x12mm pan head threading screws at the right side.
- Two M3.5x8mm pan head threading screws at the left side.
- Flap Spring.
- Optical Sensor -- unhook it and let it dangle.

24) Pick Rolls
- If early-style pick rolls (40X0070) are in place, the retaining claws can easily be deflected too far and snapped off. Later-style pick rolls (40X4308) were redesigned to preclude that happening.
- If reinstalling early-style pick rolls, note the arrows on the hubs indicating direction of rotation. Only the later-style pick rolls should be used as service replacements. See this post for more information.
- Check the operation of the one-way clutch that's integral with the pick roll axle. It should turn freely in the feed direction; lock in the opposite direction.

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

26) White Glide
- It just slides out to the right.

27) Transfer Roller
- Pry up by its left side bearing to free it.
- Handle the roller with a paper towel. Avoid touching the roller's surface.
- NOTE that the gear goes to the right side.
- Blow off any toner. The shaft ends that ride in the bearings should be immaculately clean. Use Varsol and/or methyl hydrate sparingly to clean them.

28) Charge Roller
- Handle the roller with a paper towel. Avoid touching the rollers' surface.
- Clean only by blowing off.
- It's all but impossible to judge a charge roller's fitness for service by its appearance. Only a print test will show if it's satisfactory.

29) Post-Transfer Paper Deck
- Two outward-hooking claws underneath at front left and right.
- One M3x8mm pan head threading screw at the ground wire terminal.

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

31) Printhead
- Inspect the printhead's output 'window' for dust or debris. A flashlight and a mirror from a lady's makeup compact are helpful. It's sometimes possible to blow off the window by flexing the 'straw' of a duster can to point up at it. If that doesn't work, unfasten the printhead and flip it over to clean the window thoroughly. NOTE the following before loosening any screws:
- There are three screws to be removed. There's a fourth screw daubed with red varnish that shouldn't be disturbed.
- At the screw at the right front, take a sharp HB pencil and trace the perimeter of the screw's captive washer so as not to lose the factory-set position of the printhead.
- Three M3.5x12mm pan head threading screws w/oversize captive flat washers.

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.
- Apply the WD-40 at each end of the clutch's control collar so it can wick down into the clutch spring.

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

35) Transfer and Charge Roller Bearings
- Clean these with a Q-Tip and Varsol followed by methyl hydrate.
- The bronze bearings especially should be immaculately clean. No lubricant of any kind is to be applied to them or to the plastic bearings at the left side.

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.

# # #

FEEDBACK

# # #

Oki 320/1 Turbo, 420/1 Line Feed Losses

Symptom: The vertical print position on continuous forms creeps upward.

Cause: Worn/damaged gear teeth on the change gear.

- - -

Here's a view of the gear-train.


The rearmost gear (right side of the photo) is the tractor drive gear. Those usually last the life of the printer.

Below and in front of the tractor drive gear is the tandem change gear that provides friction/tractor-feed selection. In front of that gear is the idler gear.

The change gear leads a hard life, and is prone to getting chipped teeth -- random line feed losses ensue. Here's a close-up of a change gear with a missing tooth.

The damage to a tooth needn't be that severe for line feed losses to occur. Even slight tooth damage that can barely be seen will cause trouble so, when the symptom shows up, replace the change gear and the idler gear just in front of it.

Change Gear P/N 51228001.

Idler Gear P/N 51238501.

Remove the reset leaf spring and the tractor drive gear. (One side of that gear's square hub is a claw that holds the gear on the shaft.)

Remove the idler gear and the change gear. (NOTE that the idler's extended hub goes inboard; the change gear's small end goes outboard.) Clean their spindles.

Grease the spindles and the gears' bores liberally. Do not grease the gears' teeth; grease on the teeth will just attract and retain paper dust. Grease the reset leaf spring's working surfaces.

- - -

Wear in the gears' bores will cause the same symptom as damaged gear teeth do. Gear mesh has to be full and flawless for this gear train to work reliably

On printers that have seen long, hard service, the change gear's spindle may be worn, and even new gears won't provide reliable line feeding -- the worn spindle results in marginal gear mesh. The only solution is to replace the chassis. That's actually quite doable, but it does take a complete teardown and transfer of components.

# # #

FEEDBACK

# # #

CA (Cyanoacrylate) Adhesive

Commonly known as Krazy Glue or Super Glue, CA adhesive is indispensable in the workshop. Following are a few brief points about it:

a) It bonds skin instantly. The stuff can be dangerous.^[1]

b) Dollar stores carry it. I've found the dollar store stuff to be perfectly good for my purposes, and considerably less expensive than the brand name products.

c) There's a gelled version available, but I really can't imagine why. One of the adhesive's biggest virtues is that it's extremely runny. It will wick into the tiniest gap or crevice.

d) Runny though it is, it can be made to 'build' with repeated applications. That can be very helpful in the restoration of rusty old machinery; small unwanted crevices can be filled with it. The resultant fill can be filed or sanded, is impervious to water or oil and can be painted.

e) Further to its use as a filler, I've read that you can fill a larger gap with baking soda, then apply drops of CA. I've yet to have tried this myself. I suspect that pungent fumes result when it's done. Some types of applications result in fumes, and this is likely one of them.

f) It's not terribly heat resistant. LePage's website advises that immersion in boiling water can soften cured adhesive, so it's likely unsuitable for any application that will subject it to temperatures approaching 100° C. That said, you can safely use it as a threadlocker, or for any machinery assembly application that may need to be taken apart again. Just as with threadlockers, sufficient heat will soften it.

g) Its water and chemical resistance is impressive. I've read that acetone will soften it. Apart from that, though, the stuff seems to stand up to just about anything.

h) Keep it in the fridge. Heat, light and humidity all tend to thicken it. Kept in the fridge, a tube of it will stay fresh and runny; you'll get the use of all of the tube's contents.

i) I've read that if it gets on cotton, it generates a lot of heat as it sets, enough heat to be dangerous.

j) There are many specialized versions available, but you have to go to industrial supply houses for them. So far, I've gotten by fine with the common variety. There's much more information about the material available on the web.

- - -

Note:

[1] There's a flipside/upside to this.

If you're plagued, as I am, by splits in fingertip skin through the winter months, CA adhesive is a therapeutic. The instant you acquire a fingertip skin split and notice the attendant pain, seal the split with CA adhesive. The pain stops. The split is cleanly sealed against infection and can heal from beneath undisturbed.

I've read that some individuals may find the adhesive irritating and consequently useless for this, but it works for me.

# # #

FEEDBACK

# # #

HP LJ 2420 Gear Kit P/N KIT-24xx-GR-NN

The kit consists of three gears:

1) Narrow, rearmost 19t gear P/N RU5-0379.

2) Wide, upper-frontmost 21t gear P/N RU5-0377.

3) Lower-frontmost 20t gear P/N RU5-0378.

Item '3)' is the one that leads a hard life and wears out, making for a noisy gear train.

Each gear is held on its spindle by a claw -- they're easily removed. Replace all three. Grease the teeth. Lubricate the spindles with WD-40.

HP LJ 2420 Fuser Access

The 2420's fuser is not user-replaceable, but it's not difficult to get at and replace.

There's a set of three gears that should be replaced whenever a fuser is replaced. You have full access to them once the fuser is out. The set of gears is P/N KIT-24xx-GR-NN. See this post for more infromation.

Proceed as follows to remove the fuser:

1) Tray 2

2) Rear Cover/Door Assembly
> Pull the rear door fully open.
> Two M4x10mm pan head threading screws.
> Two claws within the tray 2 cavity.

3) Mains Receptacle Bezel
> Treat as if hinged at its outboard long edge.
> There’s a single downward-hooking claw about 3 3/8" below its top edge. If the item is stubborn, slide a thin tool in behind it about 4" below its top edge and move the tool upward. You’ll unhook the claw.

4) Black Plastic Cover at Left Side (Your right.)
> One claw/latch -- it has a ‘handle’ extending rearward.
> Pull the cover toward you. A spring hook is helpful.

5) Fuser Power Cable
> It's at the lower right just below the line cord receptacle.

6) Exit Sensor Cable (Violet)

7) Thermistor Cable (Yellow and white.)
> Free the cable from its white restraint. The restraint can be unlatched with a fingernail or a small screwdriver.

8) Duplexer Input Ramp
> Two claws -- they have ‘handles’ extending rearward.
> Push up on the claw handles and pull the ramp toward you.

9) Fuser
> Three prominent M4x10mm pan head threading screws.
> One M3x6mm pan head screw w/captive star washer. It’s in a recess at the fuser’s lower right.
> Tug on the power cable and the green wheel to coax the fuser out the back.

HP LJ 1320 -- Flashing Amber LED; Motor Doesn't Run

A flashing amber LED on the 1320 can mean any of several things, but when the motor doesn't run at all it's a giveaway that the cover interlock switch is not being made. The interlock actuator is a rectangular plastic projection at the upper-left corner of the toner cartridge access door. The projection is about 5/8" long, long enough that it's a bit fragile and easily bent over rightward by a careless user.

In the instance we encountered, we were able to bend the projection back to straightness without it breaking off.

Terminology -- Circuit Boards

The terminology in this industry is a bewildering mess of ill-conceived and sloppily applied terms. Nowhere is that more evident than with respect to the major circuit boards typically found in laser printers. I'll attempt to clarify the subject here.

First, though, we need to clear away some clutter.

The terms 'board', 'circuit board', 'logic board', 'printed circuit board (PCB)' and 'printed circuit assembly (PCA)' all mean the same thing -- a thin, flat, usually rectangular piece of insulating material with conductive traces and electronic comonents and connectors on it. I'm partial to 'PCA' (Printed Circuit Assembly), and in writing I always use that term following a circuit board's name; e.g. Formatter PCA or DC Controller PCA. With that out of the way, let's get on with engine controllers and formatters and system boards and the like -- they're the source of much confusion.

Early Days -- The LaserJet II and Lexmark 4019

In any monochrome printer, there are two distinct functions at work. One is engine (mechanism) control; the other is page composition.

In the LaserJet II, engine control was done by the DC Controller PCA; page compositon was done by the Formatter PCA.

In Lexmark's 4019, the engine control and page composition functions were combined on a single PCA -- the System PCA.

Engine Control PCAs

HP has been fairly consistent with the use of DC Controller PCA for the engine control PCA's name.

Lexmark has made models with separate engine control and page composition PCAs. For those machines, Lexmark uses the term Engine Controller PCA, not DC Controller PCA.

HP uses the term Engine Controller PCA as well, but they reserve its use for PCAs that have the engine control function and the power supplies combined on them. Many of HP's modern crop of compact machines are constructed this way.

Formatter PCAs

Formatter PCA continues to be HP's term for a page composition PCA.

Where Lexmark has made machines with separate engine control and page composition PCAs, they've used the term RIP PCA for what HP calls a Formatter PCA. 'RIP' stands for 'Raster Image Processor'. (If you're familiar with the operation of CRT displays, you'll certainly recognize the term 'raster'. Laser printers employ rasterization as well.)

Main Logic PCA

'Main Logic PCA' is liable to mean System PCA or Formatter PCA or RIP PCA. It's a term that's best avoided, really, but it does crop up.

# # #

Lexmark T-Series 500-Sheet Tray Teardown

This procedure gets you access to the electronics and the pinch roller drive/tensioning mechanism.

1) Upper Front Paper Guide
- One M3.5x8mm pan head threading screw.

2) Light-Coloured Upper Front Face (T64X Only)
- Four M3.5x8mm pan head threading screws from underneath.

3) Autocompensator Assembly
- NOTE the relationship of the paper out sensor flag to the actuating stud on the arm of the autocompensator. The stud goes under the curved ramp on the flag.
- Two cable connections.
- Three M3.5x8mm pan head threading screws.
- Unhook the retraction spring.
- Lift the item away.

4) Paper Out Sensor Flag
- Rotate it back a bit and it can be lifted out.

5) Electronics/Mechanism Box
- Two M3.5x8mm pan head threading screws at upper front and rear (not present on later units).
- Four M3x15mm pan head screws w/captive washer (T10 Torx recess).
- Two M3 nut plates.
- NOTE: At reassembly, don't bother putting back the two lower screws -- they're just a needless nuisance.
- Pass-Through Sensor -- dismount it and free its cable from its restraint slot.
- Two claws -- one high up in front; one low at the rear. The front one is easily accessible. Free the rear one by inserting a 1/4" slot screwdriver and rolling it to push the claw forward.
- The box is now free to be lifted out.

# # #

FEEDBACK

# # #

Lexmark T430 Fuser Replacement

You'll want to keep the toner cartridge access door closed while you're inserting a fuser. There's a linkage in the machine between the door and and a crank rod on the fuser. With the door closed, the linkage is sure to re-engage correctly when you put a fuser in.

Some of the screws involved are in fairly deep wells; you have to look for them.

1) Cartridge


2) Tray 1

3) Top Cover -- Loosen its Rear End
- Two M3x10mm washerhead threading screws; the two highest screws at the rear. (They're in deep wells.)

3) Left Side Cover
- Two finger-operable claws at the front.
- Swing the cover out enough that you can move it rearward to unhook it at the back.

4) Right Side Cover
- One M3x10mm washerhead threading screw under the toner cartridge access door.
- One M3x10mm washerhead threading screw in a deep well at the upper rear.
- One claw at the front by the tray 1 opening.

5) Rear Cover/Door Assembly
- One in-line cable connection at the left side, lower rear.
- Three M3x10mm washerhead threading screws.
- NOTE that one of the screws is very low down by the tray 1 cavity at the right.

6) Fuser
- Toner cartridge access door closed.
- AC power cable -- unplug it and free it from its hook-restraint.
- Exit sensor cable (three-conductor).
- Thermistor cable (two-conductor).
- Four M3x10mm washerhead threading screws -- two are high up and easily seen; the two lower ones are quite far forward inside the machine.
- Pull the fuser out the rear of the machine.

# # #

FEEDBACK

# # #

Lexmark T-Series Tray 1 Pickup Roller Replacement

See this post for information on service replacement rollers.

Remove Tray 1 and you have access to the pickup rollers. It's helpful to have the machine positioned so that its front is hanging out over the work surface a few inches.

The rollers are each held in place by a small claw at the end of the axle. Flex the claws inward slightly to allow the rollers to be slid off the ends of the axle. You will encounter the odd roller that won't slide off easily. Be careful not to overflex the claw when this happens, the claws are easily snapped off. Just flex the claw enough that it's not restraining the roller, and apply force as required to get the roller off the axle. The redesigned rollers (40X4308) limit the amount of claw flexure that's possible. It's only the early rollers (40X0070) that present this problem.

When installing or reinstalling early rollers, note and observe the directionality arrows on the hub. The new rollers have no directionality to them.

You may encounter an early roller that's been glued to its axle because its retaining claw got snapped off. In such a case, the only way to renew the roller will be to remove and replace the roller's tire in situ. Extra care must be taken to ensure that the tire's directionality is kept correct.

Whenever you're inspecting pickup rollers, check the action of their axle's one-way clutch as well. The axle should turn freely in the direction of paper feed. It should lock up when turned in the opposite direction. A defective clutch calls for replacement of the complete autocompensator assembly.

Lexmark 241 Errors

A 241 error indicates that paper failed to leave Tray 1 and reach the registration sensor after a pickup cycle was executed. Following are some likely causes:

a) Worn early-style pickup rollers with insufficient traction. See this post for information on the new-style service replacement pickup rollers.

b) Toner/paper-dust fouling the pickup rollers. Scrubbing the rollers' tires with a tooth brush and methyl hydrate may clear it up, but when machines get that filthy, they're usually due for a proper overhaul in the shop.

If the rollers are ok but you're getting solid, not intermittent, 241 errors, there's likely an outright hardware failure causing it. We've seen two such in our shop:

1) Failure of the auto-compensator to lower down onto the paper stack.

On the upper right side ledge of Tray 1, about half way back, there's a vertical protrusion that causes the auto-compensator to drop when the tray is pushed in. If that protrusion gets snapped off, the auto-compensator will remain in its retracted 'up' position, spinning its wheels in the air to no effect. Replace the tray.

2) Failure of the one-way clutch in the pickup rollers' axle.

If you take the tray out and try to rotate the pickup rollers by hand, they're supposed to turn freely in the direction of paper feed, but lock up in the opposite direction. If they turn freely in either direction, the axle/clutch has a defect. Replace the auto-compensator assembly.

In closing, I should point out that whenever you're getting 241 errors, it can be helpful to get a look at what's happening as the machine is attempting to execute a pickup cycle. If you remove the redrive assembly from the rear of the machine, you're afforded quite a good view inside the tray. Both of the hardware failures described immediately above became obvious when I got a look inside that way. Unfortunately, the add-on trays don't permit such a view, short of sawing off their rear covering.

# # #

Lexmark T64X Fuser Teardown/Overhaul

[NOTE: There's a condensed 'checklist' version of this document here.]

Proceed as follows:

1) Left Side Lamp Terminal Cover
- Two M3x6mm pan head screws.
- One rearward-gripping claw.

2) Left Side Lamp Terminal

NOTE 1: The screw w/captive washer at the electrical connection is sometimes extremely tight, and the plastic will break nearby before the screw breaks loose. To prevent this from happening, grasp the plastic on either side of the screw head with slip-joint pliers, and support it as you torque the screw to loosen it.

- One M3x6mm pan head screw at plastic base.
- One M3x5mm screw w/captive washer at electrical connection.

NOTE 2: Scrape the lamp contact's surfaces where it contacts the lamp terminal with a small screwdriver. The contact surfaces must be clean and bright. Contacts that show evidence of arcing and can't be easily made clean and bright must be replaced.

3) Lamp
- Only handle the lamp with a paper towel around it; the lamp's surface should not be touched. If a lamp does get anything oily on it, clean it w/methyl hydrate.
- Burnish the lamp's contacts with synthetic steel wool. Pitted contacts that cannot be made clean and bright call for replacement of the lamp.

4) Thermistor Cable
- Unplug it and free it from its restraints.

5) AC Spade Connector at the upper right of the top cover
- Disconnect and clean up any oily residue there.

6) Top Cover
- Two M3x6mm pan head screws.
- Check that the thermal fuse's screws are snug.

7) Stripper Bar Torsion Springs

8) Exit Roller
- Two self-latching bearings.
- NOTE that the flanged gear must mesh with the idler gear; the flange is the idler gear’s retainer.

9) Idler Gear

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

11) Ring Gear
- One external snap-ring.

12) Left Side Bearing^[1]

13) Hot Roller w/Bushings^[1]

14) Right Side Bearing^[1]

15) Input Ramp
- Spread the sides of the frame A/R to free it.

16) Stripper Bar
- Spread the sides of the frame A/R to free it.

17) Pressure Roller w/Bearings and Bearing Holders^[2]
- NOTE: Any evidence of flat-spotting or delamination is cause to replace this roller. A flat-spot will cause a thumping noise; delamination will only get worse.

- - -

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.
- Reassemble w/new parts A/R.

- - -

18) Output Ramp
- Two sensor cable connections.
- Spread the sides of the frame A/R to free it.
- Examine the sensor toggles. They must move freely and return to their upright positions smartly. Any tendency for them to bind or stick will result in paper jam errors

19) Pressure Roller Springs

20) Right Side Pressure Roller Arm^[3]
- One E-Clip.

21) Left Side Pressure Roller Arm and Link^[3]
- One E-Clip.

NOTE: The following three steps complete the tear-down, but for reasonably clean units they can be dispensed with. Only proceed with them for units with dirty frames that need to be washed. Whether you remove it or not, examine and scrape the right side lamp contact as was done for the left side contact.

22) Right Side Lamp Contact Assembly
- Two M3x6mm pan head screws.
- One bulkhead connector.

23) PCA
- Solenoid cable connection.
- Two M3x6mm pan head screws.

24) Solenoid
- One M3x6mm pan head screw.


26) Reassemble w/new parts A/R

- - -

Notes

[1] Re Hot Roller and bearings:

Hot rollers can look pretty bad but still work fine. That said, any hot roller that's not in perfect condition should be replaced for longest service life of the fuser.

Bearings that turn freely but with a slight feel of grease resistance to them are ok to re-use. Bearings that spin very freely are likely grease-starved and should be replaced. If at all in doubt, replace the bearings. As with the pressure roller bearings, there's really no way to judge life expectancy.

[2] Re pressure roller and bearings:

Rusty looking spindle ends indicate that the roller has been turning in seizing or seized bearings. Both the roller and its bearings must be replaced, even if the roller looks fine otherwise.

Bearings that turn smoothly and exhibit a bit of grease seepage are ok to re-use, but there's really no way to judge bearing life expectancy. These bearings are fairly heavily loaded for their size. Unconditional replacement is probably the best practice.

Some T64X fusers do not use plastic holders for the pressure roller bearings; the arms have been redesigned to accept the bearings directly -- a later design change, presumably.

[3] Re Pressure Roller Arm Pivots

The grease applied at the factory does not age well. It turns to a stiff sludge that interferes with the arms' freedom to pivot as they should. It takes lacquer thinner and a small brass-bristled brush to get the pivots clean.

Grease the pivots and the ends of the solenoid link at reassembly. The grease we use is Lubriplate No. 930-AA.

- - -

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

# # #

FEEDBACK

# # #

Auto Paper Size Sensing

The cassette trays, both integral and add-on, all have auto size sensing. It's based on sensing the position of the tray's backstop. The backstop is attached to a sliding key inside the left wall of the tray. That key's position determines the combination of three plastic 'fingers' that protrude from the left side of the tray. Here's a view of them.^[1]



Pictured is the letter size setting -- the two lower fingers protrude, the upper finger is retracted. Those fingers act on leaf-spring actuators in the tray's cavity, pictured in the following photograph.



The actuators, in turn, act on three small snap-action switches on a circuit board (printed circuit assembly -- PCA) that's in behind the System PCA. Here's a view of the size sensing PCA in a T640 that's had its system PCA removed. (All the earlier Ts and the old Optra S are much the same.)



And here's a component-side view of the PCA itself.



At the right side are the three little pushbutton switches that inform the system PCA of the tray's size setting.

The switches tend to get flaky after long service, and size sensing becomes erratic; e.g. if the second switch up doesn't make when actuated, the machine will sense A5 size instead of letter size. It's easy to check the switches thanks to the paper size reporting feature in the Paper Menu. When you're viewing a tray's size on the display, you're seeing the actual size being sensed. If you remove a tray that's set for letter size and push on only the bottom actuator, the display's size reading should change to A5. To check for flaky size sensing, simply pull the tray out a bit and shove it back in several times slowly. If you even once see the size reading change from what it should be, you know you have sensing switch trouble. I've been able to get switches working by taking out the size sensing PCA and soaking the switches with WD-40. Then I've actuated them many times, dried off the PCA and reinstalled it. I don't know how long the effect of that treatment lasts.

There is a work-around for a machine with flaky size sensing, and that is to disable the size sensing feature. Invoke the CONFIG MENU. Scroll down to the item 'SIZE SENSING' and select it. There, you'll be able to change the size sensing from 'Auto' to 'Off'. With that done, when you go to the user's 'Paper Menu', you'll be able to specify the size for the tray and it won't matter that the size sensing is faulty.

- - -

[1] From the Optra S through the T640, the fingers are the same. So, any scrapped machine of those models is a source of replacements for damaged ones.

# # #

Lexmark T64X Routine Teardown/Overhaul

[NOTE: There's a condensed 'checklist' version of this document here.]

Following is our standard procedure for an in-shop overhaul of a T64X series printer. The procedure assumes a machine that's basically in working order, but in need of a teardown, a thorough cleaning and a fuser overhaul.

The developer drive, main drive and the paper alignment assembly are left undisturbed; they normally don't require attention. In cases of severe toner spillage, those items do need to be removed and cleaned/overhauled.

PRELIMINARIES:

1) Auto Size Sensing; Tray Bias Roller
- See this post for information on checking and servicing the auto size sensing feature.
- Inspect the tray bias roller that's just inside the tray cavity at the right side. The roller must be free spinning and have no flat spots. Flat-spotted rollers must be replaced. The part is accessible once the right side cover has been removed. See this post for more information.

2) Maintenance Count
- To view the accumulated page count since the last time anyone cleared it, press and hold the 'check mark' and 'right arrow' keys while powering on. That invokes the CONFIG MENU where you can check and clear the maintenance count. Clear the maintenance count after you're done testing the completed machine.

3) Page Count
- The page count and the permanent page count can both be found in the DIAGNOSTICS menu within PRINTER SETUP. To invoke the DIAGNOSTICS menu, press and hold the 'down arrow' and the 'right arrow' keys while powering on.

4) Event Log
- The event log is an item in the DIAGNOSTICS menu.
- An empty event log is likely due to early firmware. A machine that's been taken off-site and brought to the shop is unlikely to have had no error events. A firmware update is in order whenever you see an empty event log.
- When there are items in the event log, note what they are. They're usually just paper jams and the like. The presence of printhead errors calls for printhead replacement. The machine is likely to be written off because of the high cost of the part.
- Clear the event log after you're done testing the completed machine.

ORDER OF WORK:

1) Toner Cartridge
- Machines seldom come into the shop with a toner cartridge. When they do, be sure to note it and label the cartridge so it goes out with the printer. If the cartridge has a defect, it should still go out with the printer, but clearly labelled that it's defective.

2) Paper Tray (Tray 1)
- Check that the backstop is linked to the size sensing key and is operable. When set for letter size paper, the two lower sensing fingers should protrude, the upper finger should be retracted.
- The four black ramps in front must be clean. Trays that have been used for sheets of labels are liable to have label adhesive muck fouling the ramps. Clean A/R with Varsol and/or methyl hydrate.
- Examine the pass-thru slot at the front of the tray for stuck labels or damage.

3) Redrive Cap
- Lift it up at its right side end to remove it.

4) Fuser Cleaning Wand Cover
- See this post regarding a defect in this item.

5) Fuser Cleaning Wand
- NOTE that the felt strip is removeable and reversible.
- In place of a cleaning wand, there is often an item that's just a cover for the cleaning wand cavity. It will have a small handle at the centre. The handle goes to the rear.
- You may encounter a cleaning wand or a cleaning wand cavity cover that has three protrusions on top that are meant to be gripped by claws on the underside of the cleaning wand cover. One or more of the claws are likely to have broken off -- the heat gets to them. We don't bother replacing covers with broken claws, they're a pretty useless feature, really. But should you encounter a user who insists on having a fully intact cover, the part number for a new cleaning wand cover is 40X0001.

6) Paper Support
- Tip it up and pull it off its hinges.

7) Back Door
- Open it to about 30º from vertical and you can pull it away off its hinges.
- Check that the duplexing deflector's torsion spring is in place and correctly hooked at its ends. The deflector must pivot freely, and return smartly to its at-rest position when released.

8) Redrive Assembly
- Two M4x8mm pan head thread-rolling screws.
- Two outward-hooking claws, left and right side, high up.
- Check that the output diverter is in place in its bearings and spring-loaded.
- Check that the duplex diverter push-rod is properly fastened and free moving. If the little fasteners/glides show any sign of being loose, apply a drop of CA adhesive to cement them in place permanently.

9) Left Side Cover
- Two finger-operable claws at the front. Swing it open far enough and its upper hinge will pop apart harmlessly for removal.

10) Right Side Cover
- One M3x22mm washerhead threading screw from high up inside the redrive cavity (M3x10mm on the T642 and T644).
- One M3x10mm washerhead threading screw from inside the cartridge cavity.
- One claw at the front just above the MP Feeder.

11) MP Feeder Door/Platform
- Open it to about a 45º angle and it can be pulled off its flatted hinge pins.
- If this item is really filthy, it can be easily dismantled for washing. There are just the three obvious m3x8mm pan head threading screws holding it together.

12) Fuser
- Power cable in-line connection.
- Signal cable connection at PCA.
- Two M4x8mm pan head screws w/captive washers.

13) Power Supply
- One M3x6mm pan head screw at the black plastic connector access cover.
- Connector access cover -- it can dangle from the cable that’s strung through it.
- Two M3x6mm pan head screws.
- Unplug the large connector. If the locking tab is obstinate, use Channelocks to squeeze it open, while gently prying at either side to free the connector.
- The power supply slides out the right side until you can disconnect the fuser power cable and slide it out completely.
- NOTE: The early power supply design really fills up the space available for it. It can tend to hang up and be a bit difficult to slide out. Jiggle it A/R to coax it out. There's a later design that's much less bulky.

14) Control Panel Cover & Window
- Two M2x8mm washerhead screws from in behind (they're No. 1 Phillips recess).
- Tug forcefully at the upper rear lip and the cover will come away.
- The window is free to be removed once the cover is off.

15) Top Cover
WARNING: Unlike earlier models, once the top cover has been removed from a T640 there’s nothing to stop the toner cartridge access door frame from coming free of its hinges. If you mean to set the machine on its back, be certain the door is closed and latched first so it can’t come free with possibly damaging results.
NOTE: At the upper right rear corner there may be a screw w/captive washer. It need not be removed. The tab it’s associated with is not actually fastened in place by the screw.
- One M3x10mm washerhead threading screw at the right side -- it’s a bit tucked away below the rearward curve of the cover.
- Three M3.5x12mm threading screws w/captive oversize flat washer.
- Close the toner cartridge access door.
- Yank the cover up at the front and force it up past the upper lip of the toner cartridge access door. It’s then free to be worked clear of the bin-full sensor toggle.)

16) System PCA Enclosure Cover
- Loosen off six M3x6mm pan head screws.
- Slide the cover forward slightly and pull it away over the screwheads.

17) PTO Cover
- One M3x8mm washerhead threading screw.

18) 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.
- Check for any accumulation of label adhesive muck on the item's undersurface. Clean with Varsol and/or methyl hydrate A/R.
- 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.

19) MP Feeder Pick Roll
- One claw. Don't over-deflect it. It's easily snapped off. In the event of a claw snapping off, a small (3") ty-wrap works fine as a retainer.
- Blow off the paper dust and clean the tire with lacquer thinner.

20) MP Feeder Lower Deflector/Elevator Flap Assembly
- NOTE 1: This item is easily removed, but can be awkward to get back in place. Before proceeding, note carefully the relationship between the MP Feeder’s pickup cycle cam, and the cam follower that’s integral with the Elevator Flap. Keeping that relationship in mind at reassembly will be helpful.
- NOTE 2: At reinstallation, wipe off the face of the separation pad with methyl hydrate prior to putting the pickup roller back on its shaft.
- One M3x10mm washerhead threading screw at the solenoid's base.
- Two M3x12mm washerhead threading screws at the right side.
- Two M3x10mm washerhead threading screws at the left side.
- Flap Spring. NOTE that the bottom end of the spring must be seated correctly in its channel so that it will contact the steel frame of the paper feed alignment assembly. It’s the ground continuity contact for the elevator flap.
- Optical Sensor -- unhook it and let it dangle.

21) Pick Rolls
- If early-style pick rolls (40X0070) are in place, the retaining claws can easily be deflected too far and snapped off. Later-style pick rolls (40X4308) were redesigned to preclude that happening.
- If reinstalling early-style pick rolls, note the arrows on the hubs indicating direction of rotation. Only the later-style pick rolls should be used as service replacements. See this post for more information.
- Check the operation of the one-way clutch that's integral with the pick roll axle. It should turn freely in the feed direction; lock in the opposite direction.

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

23) Transfer Roller
- Pry up at its left side bearing to free it.
- Handle the roller with a paper towel. Avoid touching the roller's surface.
- NOTE that the gear goes to the right side.
- Blow off any toner. The shaft ends that ride in the bearings should be immaculately clean. Use Varsol and/or methyl hydrate sparingly to clean them.

24) Charge Roller Assembly
- Handle the assembly with a paper towel. Avoid touching the rollers' surfaces.
- Clean only by blowing off.
- It's all but impossible to judge a charge roller's fitness for service by its appearance. Only a print test will show if it's satisfactory.

25) Post-Transfer Paper Deck
- Two outward-hooking claws underneath at front left and right.
- One M3x8mm washerhead threading screw at the ground wire terminal.

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

27) Printhead
- Inspect the printhead's output 'window' for dust or debris. A flashlight and a mirror from a lady's makeup compact are helpful. It's sometimes possible to blow off the window by flexing the 'straw' of a duster can to point up at it. If that doesn't work, unfasten the printhead and flip it over to clean the window thoroughly. NOTE the following before loosening any screws:
- There are three screws to be removed. There's a fourth screw daubed with red varnish that shouldn't be disturbed.
- At the screw at the right front, take a sharp HB pencil and trace the perimeter of the screw's captive washer so as not to lose the factory-set position of the printhead.
- Three M3.5x12mm pan head threading screws w/oversize captive flat washers.

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.
- Apply the WD-40 at each end of the clutch's control collar so it can wick down into the clutch spring.

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

31) Transfer Roller Bearings
- Clean these with a Q-Tip and Varsol followed by methyl hydrate.
- The bronze bearing especially should be immaculately clean. No lubricant of any kind is to be applied to it or to the plastic bearing at the left side.

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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