Brother MFC4820C Service Manual page 54

[ 1 ] Structure of the air pump & motor module
The air pump & motor module consists of an air pump motor (DC motor), diaphragm pump, and
encoder. In a purging operation (initial purge or reset purge), the air pump motor will be driven
together with the purge motor. It causes the pump to feed air into the ink cartridges, thereby
changing the pressure in the print head unit from negative to positive to improve the ink output
reliability. The air pump motor is feedback-controlled.
For details on the purging operation, refer to Section 4.2.3.3, "Purging mechanism."
Air pump motor (DC motor)
Pump motor encoder sensor
Each air pump & motor module has its own individual properties. When a particular module is
installed in the machine, its property data are stored in the EEPROM of the driver PCB. The
controller manages the motor rpm to generate the positive pressure suitable for that module
according to its property data. To do this, the controller monitors the motor rpm with the air pump
motor encoder and accelerates/decelerates the motor according to the speed change using PWM
control.
A property label, on which a property code is printed, is attached to the air pump & motor module
itself as well as on the rear left side of the machine (with the battery cover* or rear cover S**
removed).
If you replace the module with a new one, you need to enter a property code (19-digit) into the
EEPROM in the maintenance mode (Function code 68) and replace the property label with the one
that comes with the new module.
Pump motor encoder disk
(*For the MFC4820C, **For the MFC4420C.)
Property code
(19-digit)
4 -1 3
Diaphragm pump