HP Color LaserJet 8550 Multifunction Printer series - Manual (Page 198)

EN Print Quality Problems 197
Cleaning the Density
Sensor
Clean the density sensor after replacing
the imaging drum and when printed
colors are inaccurate.
To clean the density sensor and
erase lamp
1 Open the upper door on the right side
of the printer.
2 On the inside of the door, locate the
density sensor and the density
sensor brush. Use the brush to brush
off toner particles from the density
sensor and the erase lamp. Then
replace the brush.
Note
You can also use a hand wipe to clean
the density sensor. To prevent scratches
on the sensor, do not use any paper
products, such as tissue or paper towels,
to clean the sensor.
3 Close the upper right door.