Monday, October 17, 2011

HP LaserJet 4+/5 -- Fuser Overhaul

[The LaserJet 4's fuser is very similar, but many part numbers are different.]

Proceed as follows:

1) Cover, Upper Front (P/N RF5-0738)
- Two outward-gripping claws low in front, accessible via rectangular openings.
- Four claws high up.
- NOTE: This part is liable to have become brittle with age and break as it's removed.

2) Red and White Wire Terminals at Upper Front
- Two M3x6mm bright pan head screws w/captive washers.
- Free the red wire from its channel.

3) Two Coil Springs at Upper Rear

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

5) 90° Spade Terminal
- Disconnect it.
- NOTE: This is a locking terminal. There's a little lock button in the centre of the female terminal. You need to push on that with the point of a scriber to free the terminal.
- Free the long white wire from its channel.

6) Right Side Black End Cap (P/N RF5-0736)
- One M3 shoulder screw w/wavy washer at upper front.
- One M3x6mm bright pan head screw w/captive washers at lower rear.

7) Upper Gear (23t -- P/N RS5-0393)

8) Lower Gear (19t -- P/N RS5-0231)

9) Left Side Black End Cap (P/N RF5-0737)
- One M3 shoulder screw w/wavy washer at centre front.
- One M3x6mm bright pan head screw w/captive washers at lower rear.

10) Left Side Pressure Release Lever, if present
- P/N RB1-3523.

11) Lamp (P/N RH7-4054)
- NOTE that the red wire is at the left side.
- Room temperature resistance is approx. 1.6 ohms.

12) Thermal Fuse Block (P/N RG5-0881)
- One claw.
- Slide it rightward to free it.

13) Thermistor Cable Receptacle/Cable
- Free it from its restraints.
- NOTE that the slotted side of the receptacle faces forward.

14) Entry Ramp (P/N RB1-3518)
- Two claws -- it slides out the front.

15) Top Cover (Sheet Metal)
- Two tabs at the rear. It pivots up and comes away.
- NOTE: The thermistor is P/N RH7-7054. Room temperature resistance is approx. 260 kohms.

16) Ring Gear (42t -- P/N RS5-0388)
- One snap ring.

17) Right Side Pressure Release Lever, if present.
- Right Side P/N RB1-3527.

18) Coated Roller (P/N RB1-3516)
- NOTE: You'll need to wedge the pressure roller away from the coated roller to remove this part safely. Force each end of the pressure roller downward and insert the end of a 10-32 or 5mm screw to hold down the bearing.
- Carefully slide the roller out through its left side bearing.
- Remove the two screws.
- NOTE the slip ring and snap ring that must be transferred to a new roller when this roller is replaced.

19) Upper Rear Black Bar (Separation Guide -- P/N RF5-0744)
- Spread the frame a little to free it.
- REINSTALLATION NOTE: The exit sensor toggle must end up behind the pivoting bar.
- NOTE: The exit sensor toggle is P/N RB1-3522.

20) Right Side Coated Roller Bearing (w/one hole and one slot -- P/N RS5-1097)
- One M3x6mm bright washerhead screw.

21) Left Side Coated Roller Bearing (w/two holes -- P/N RS5-1098)
- One M3x6mm bright washerhead screw.

22) Pressure Roller and Bearings
- Each bearing P/N RS5-1099.
- Pressure Roller P/N RB1-3517.

23) Pivoting Bar w/Torsion Spring (Lower Separation Guide)
- NOTE the bar's relationship to the two stop tabs on the vertical portions of the frame.
- One M3 shoulder screw.

- - -

Clean all parts A/R.

Reassemble w/new parts A/R.

# # #

No comments:

Post a Comment