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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