Brother DCP-6690CW, Service Manual, Page: 78 / 506

3-24 Confidential
Ink refill assembly components and their main roles
- Ink refill case
- Cartridge release levers
- Ink refill base and its foam
- Ink cartridge detection sensors (on the ink cartridge detection sensor PCB)
- Ink empty sensors (on the ink empty sensor PCB)
- Ink foam and its case
Pushing each ink cartridge into the ink refill case until it clicks secures it and forces the
cartridges' ink supply port into close contact with the ink refill base to prevent ink leakage.
Pressing down the cartridge release lever pops the ink cartridge out of the ink refill case.
The ink from the ink cartridges flows through the ink flow channels provided in the ink refill
base into the ink supply tubes. As the ink level in an ink cartridge drops, the pressure inside
falls, drawing air in the ink cartridge.
The ink cartridge detection sensors detect ink cartridges inserted when the machine power is
ON.
The ink empty sensors detect ink remaining in the ink cartridges loaded. An ink empty sensor
actuator blocking the light beam to an ink empty sensor indicates that there is ink in the ink
cartridge. When ink runs low, the actuator moves out of the beam, activating the sensor ("Ink
near-empty") and showing the "Ink low" message.
If any of the ink cartridges is replaced with the one having different ink volume when the
machine power is OFF, the corresponding ink cartridge detection sensor and ink empty sensor
issue different signals when the power is turned ON next time so that the controller prompts the
user to reload the ink cartridge.
At the back of the ink refill case is an ink foam that absorbs any ink that leaks from the air
intake ports of the ink cartridges loaded when the machine is tilted during transportation or in
storage, preventing ink spread in the machine.
[ 6 ] Ink supply tubes
These are made of low-density polyethylene (LDPE) providing a highly impermeable barrier
against air ingress and drying out of the ink during extended periods of nonuse. This material is
also soft and highly flexible to better withstand the sharp and frequent bending associated with
high-speed head operation repeatedly over extended periods.