HP Deskjet 400 Disassembly

4

Removal and Replacement

1. Back Case...................................................................................4-3

2. Main PCA....................................................................................4-4

3. Front Case..................................................................................4-6

4. Access Door ...............................................................................4-8

5. Input Tray ...................................................................................4-9

6. Key Panel PCA.........................................................................4-10

7. Spittoon Foam .........................................................................4-11

8. Service Station Wipers and Caps...........................................4-12

Mechanism Removal and Replacement

9. Carriage Motor.......................................................................4-13

10. Encoder Strip and Carriage Belt .........................................4-15

11. Carriage ..................................................................................4-17

12. Pinch Plate .............................................................................4-19

13. Pressure Plate Lever, Pressure Plate and Service Station.......................................................................4-22

14. Output Roller Assembly, Platen Assembly, Paper Trough, Paper Size Adjustment Bracket and In-Pinch Rollers ......4-25

15. Feed Roller Assembly and Left Support Assembly...........4-27

16. Service Station Motor ...........................................................4-29

Thi d t t d ith F M k 4 0 2

DeskJet 400 Hardware Training Guide


4-2

This manual numbers each removal and replacement procedure to help you easily locate procedures. For example, if a procedure requires you to first do another procedure given elsewhere in the manual the text may say, “First remove the

front

case

, using removal procedure 1.”

N O T EN O T E

The procedures in this chapter are removal procedures. To do the replacement

procedure, reverse the removal procedure, unless stated otherwise.

Removal and Replacement Tools

• phillips screwdriver

• electrostatic grounding heel strap

• needle-nose pliers

• flat blade screwdriver

• #13 knitting needle

• feed roller spring compression tool

• E-clip applicator ETH-5 O-type

Before You Begin

Before starting a removal procedure, do the following:

1. Remove the print cartridge. You may place the print cartridge in a plastic bag to reduce the possibility of ink clogs in the nozzles and ink loss due to evaporation.

2. Turn off the printer and disconnect the

power adapter.

3. Disconnect the interface cable.

C A U T I O N

Before working with the printer, be sure to wear electrostatic grounding heel

straps to prevent damage to the electronic components.



4-3

1. Back Case

Replacement:

Be sure the

Centronics connector cover plate

is attached to the

mechanism

and that the

Centronics connector cover plate

slides into the slot in the

back case

.

1. Be sure the clips on the Centronics plug do not block the case removal. Position them to stick straight out from the plug.

2. Push down on the top of the

back case

with the heel of your hand and move it towards the back.

3. This should release the five catches holding the

back case

to the

front case,

and the

back case

will pop off.



4-4

2. Main PCA

Tool required:

Phillips screwdriver.

1. First remove the

back case

, removal procedure 1. 2. Push the

Centronics connector cover

plate in towards the Centronics connector and pry it up and out of the notch in the chassis.

3. Remove the six connectors to the

Main PCA.

4. Pull up on both ends of the two clamps holding in the two flat cables.



4-5

5. Remove the two flat cables. 6. Unscrew the five screws holding the

Main PCA

to the

chassis

. The PCA will come off when you remove the last screw.



4-6

3. Front Case

Tools required:

Flat blade screwdriver.

1. First remove the

back case

, removal procedure 1. 2. If you have not removed the

Main PCA

, disconnect the key panel connector from the

Main PCA.

3. To release the catches at the bottom sides of the

front case

, pull out and up on each left and right side.4. To release the two catches at the top of the

front case,

push back and pull up on each left and right side of the

front case.



4-7

5. To release the tab at the bottom of the

front case

from the slot in the printer’s base, pry up on the tab with a flat blade screwdriver.

6. Be sure the envelope lever is down and does not block removal. Lift the

front case

away from the

mechanism.



4-8

4. Access Door

1. With the

front case

on the printer, open the

access door

. 2. Hold the

access door

by its sides and push down with your thumbs on the printer’s

front cover

. The

access door

pops off.



4-9

5. Input Tray

1. First remove the

back case, access door

and

front case

, removal procedures 1, 4 and 3.

2. Stand the

front case

on its left side, with the

input tray

open at a 90 degree angle.

3. Push down on the side of the

input tray

with one hand and twist up and back on the side of the

front case

with the other hand.

4. When the

front case

pin is clear of the slot in the

input tray

, remove the

input tray

by pulling it to the side.



4-10

6. Key Panel PCA

1. First remove the

back case

and

front case

, removal procedures 1, and 3.

2. Lay down the

front case

with its front side down.

3. Release the catch on one side of the key panel PCA with the fingernail of one hand and pull that side slightly up with the thumb and forefinger of the other hand.

4. Repeat step 3 for the catch on the other side of the key panel PCA. Pull the key panel PCA up and out of the

front case.



4-11

7. Spittoon Foam

Tools required:

Needle-nose pliers and flat blade screwdriver.

N O T EN O T E

Be careful not to damage the plastic service station gear with the screwdriver.

1. To remove the

spittoon foam

without removing the

front case,

open the printer

access door

and move the print cartridge

carriage

to the left.

2. If the print cartridge

carriage

is locked in the

service station,

use a flat blade screwdriver to turn the service station gear through the slot in the printer’s base. Turn the gear until it unlocks the

carriage

.

(See note below.)

3. You can use the needle-nose pliers to pull the

spittoon

foam

out of the

spittoon.



4-12

8. Service Station Wipers and Caps

Tools required:

Needle-nose pliers and flat blade screwdriver.

Replacement:

When replacing

wipers

or

caps

, be sure the

service station

is correctly aligned, see the first “Solution” in the table on page 2-18. When replacing the

color cap

, be sure the beveled edge is up to ensure correct cartridge sealing.

1. First remove the

back case

and

front case

, removal procedures 1, and 3.

2. If the

service station

is locked in position, use a flat blade screwdriver to unlock it, by rotating the service station gear through the slot in the bottom of the printer.

(See note on previous page.)

3. With the

service station

unlocked, rotate it with your finger until the

wiper

or

cap

shows.4. Remove a

wiper

or

cap

by pulling up with the needle-nose pliers.



4-13

Mechanism Removal and Replacement

9. Carriage Motor

Tool required:


1. First remove the

back case

and

front case,

removal procedures 1, and 3.

2. Remove the two connectors for the

carriage

and paper motors from the

Main PCA

.

3. Remove the carriage and paper motor wires from the wire holders on the

chassis.

4. Untwist the carriage motor wires from the paper motor wires.



4-14

5. Use the Phillips screwdriver to unscrew the two screws holding the

carriage motor.

6. Unhook the carriage motor bracket and remove the motor from the

chassis.



4-15

10. Encoder Strip and Carriage Belt

Tool required:


1. First remove the

back case, front case,

and

carriage motor

, removal procedures 1, 3 and 9.2. Press on the left end of the

upper carriage rod

to release the pressure on the E-clip; then remove the E-clip with the flat blade screwdriver.

3. Slide out the

upper carriage rod

to the left. Be sure to save the

wave washer

at the right end of the rod.4. Remove the left end of the

encoder strip

from the

encoder spring.

DeskJet 400 Hardware Training GuideRemoval and Replacement

4-16

Replacement: Whenever you remove and replace a carriage belt, you must adjust the pen to paper spacing. To do the pen to paper spacing adjustment, you must centre the lower carriage rod bushings before replacing the lower carriage rod. See chapter 5, Calibrations.

When replacing the upper carriage rod, be sure to first move the carriage to the far left. This allows the rod to immediately slide into the carriage and prevents grease on the rod from contaminating the encoder strip.

5. Turn the encoder strip to remove it from the hook on the right side of the printer.

6. With the flat blade screwdriver, remove the E-clip from the left end of the lower carriage rod.

7. Push on the right end of the lower carriage rod and free the carriage rod.

8. Remove the carriage belt from the carriage.



4-17

11. Carriage

1. First remove the

back case, Main PCA, front case, carriage motor, and carriage belt,

removal procedures 1, 2, 3, 9 and 10.

2. Unhook the clip holding the

back flex cable holder

to the

chassis.

3. Remove the flex cable from the

back flex cable holder.

4. Unhook the clip holding the front flex cable holder to the

chassis.

Thi d t t d ith F M k 4 0 2



4-18

5. Remove the

sleeve

and

bushing

from the left end of the

carriage rod.

6. Slide the

carriage

to the left off the

lower carriage rod.



4-19

12. Pinch Plate

Tool required:


1. First remove the

back case, Main PCA, and front case,

removal procedures 1, 2, and 3.

2. Remove the

carriage motor

and paper motor wires from the wire holders on the

chassis.


4. Remove the

service station

and OOPS flag wires from the wire holders on the back of the

chassis.



4-20

5. Unscrew the five screws holding the

base

to the

chassis

and remove the

base.

6. From the back, unscrew the four self-taping screws holding the print zone to the

chassis.

7. From the front, unscrew the four machine screws holding the print zone to the

chassis

, and remove the print zone from the

chassis.

8. Unhook the

pinch plate springs

from the hooks on the

chassis

.



4-21

Replacement:

When replacing the

pinch plate

, do not hook the

pinch plate springs

to their hooks on the

chassis

until after replacing the print zone. When you do hook on the

pinch plate springs

, use a #13 knitting needle to more easily hook the springs onto their hooks on the

chassis.

9. Slide the pinch plate rod to the left, until the right side of the

pinch plate

comes loose.10.Slide the pinch plate rod to the right and remove the

pinch plate.



4-22

13. Pressure Plate Lever, Pressure Plate, and

Service Station

Tool required:


1. First remove the

back case, Main PCA, and front case

, removal procedures 1, 2, and 3.

2. Remove the

carriage motor

and paper motor wires from the wire holders on the

chassis.


4. Remove the service station and OOPS flag wires from the wire holders on the back of the

chassis.



4-23

5. Unscrew the five screws holding the

base

to the

chassis

and remove the

base.

6. From the back, unscrew the four self-taping screws holding the print zone to the

chassis.

7. From the front, unscrew the four machine screws holding the print zone to the

chassis

, and remove the print zone from the

chassis.

8. Remove the loose

pressure plate

and

pressure plate lever.



4-24

Replacement:

When replacing the

base

:

1. Remove the

paper adjust lever

from the

base

.2. Use tweezers to hold back the

paper size adjustment bracket spring

while you push the lever into the clip on the

paper size adjustment bracket

, as shown in the figure below:

3. With the lever in place, fit the

base

on to the lever and the

chassis

; then screw the

base

to the

chassis.

Be sure the hook on the

base

fits into the hook on the

pressure plate

. The

pressure plate

should be free to move and will rattle when you shake the

mechanism.

9. Untwist the service station wires from the OOPS wires and remove the

service station

to the right.



4-25

14. Output Roller Assembly, Platen Assembly,

Paper Trough, Paper Size Adjustment Bracket, and

Pinch Rollers

Tool required:

Phillips screwdriver and flat blade screwdriver.

1. First remove the

back case, Main PCA, front case,

and

service station,

removal procedures 1, 2, 3, and 13.2. Use a Phillips screwdriver to unscrew and remove the

paper size adjustment bracket spring

and

spring holder

from the

left support assembly.

3. With the

paper size adjustment bracket

to the right, pry out the clip with the flat blade screwdriver and lift out the

output roller assembly.

4. Remove the

platen assembly

and the

paper trough

from the




4-26

5. Remove the

paper size adjustment bracket.

6. Lift the

in-pinch rollers

from the

paper trough.



4-27

15. Feed Roller Assembly and

Left Support Assembly

Tool required:


1. First remove the

back case, Main PCA, front case, service station, and output roller assembly.

.., removal procedures 1, 2, 3, 13, and 14.

2. Pull out the bushing to the right.

3. Bend the left wall of the

left support assembly

to the left with the flat blade screwdriver to release the

feed roller assembly.

4. Pull the

feed roller assembly

up and out of the




4-28

Replacement of Feed Roller Assembly

Tool required:

Feed Roller spring compression tool.

1. Compress the feed roller spring with the feed roller spring compression tool.

2. Pull back the pivot lever of the

left support assembly

and position the


under it.

3. Ensure the washer on the


is to the left of the transmission plate; then push the


down into the


4. Pull out the feed roller spring compression tool; then push the bushing on the


to the left into the




4-29

16. Service Station Motor

Tool required:


1. First remove the

back case, Main PCA, front case,

and

service station

, removal procedures 1, 2, 3, and 13.2. Unscrew the two screws holding the

service station motor

to the

service station assembly.

3. Slide out the

service station motor

from the slot in the

service station assembly.



4-30

HP Deskjet 400 Disassembly

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