Brother MFC 5890CN - Color Inkjet - All-in-One, Service Manual

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3-23 Confidential
- Pump switching unit
This switches the application target of the negative pressure generated by the tube pump
between the head cap for black ink, the one for color ink, and the air vent cap. Usually the
pump switching unit is switched to the opening tube to the atmospheric air so that the pressure
in the head caps and air vent cap is equal to the normal atmospheric pressure.
- Air vent cap and rods
The air vent cap and rods remove air bubbles trapped in the damper assemblies in the back
end of the head/carriage unit.
During air venting with the tube pump, the air vent cap fits tightly over the air vent unit in the
head/carriage unit so that the negative pressure applies to the air vent unit. Pushing up the air
vent rods opens the shut-off valves inside the air vent unit, removing air bubbles trapped in
the damper assemblies. (For the air vent unit, see
Section 3.2.2.1, [ 3 ] .)
- Head wiper
As the head/carriage unit moves, this wipes off any ink remaining on the head nozzle surface.
- Tube pump
A roller squeezes the main drain tube looped inside, forcing their contents toward the ink
absorber box and creating negative pressure.