HP LaserJet Pro M402d - Page 30

High-voltage power supply circuits
The high-voltage power supply contains the following separate circuits.
Figure 1-5 High-voltage power supply circuits
PRI
DEV
TR
DC controller
High-voltage power supply
To primary charge roller
To developing roller
Cartridge
Photosensitive drum
Transfer roller
Primary
charging bias
circuit
Developing
bias circuit
Transfer bias
circuit
Table 1-6 High-voltage power supply circuits
Circuit Description
Primary-charging-bias generation The primary charging bias negatively charges the surface of the photosensitive drum to
prepare for image formation.
Developing-bias generation The developing bias adheres toner to an electrostatic latent image formed on the
photosensitive drums.
Transfer-bias generation The primary transfer bias transfers the toner from each photosensitive drum onto the
page.
Fuser bias
The printer uses on-demand fusing. The fuser bias is DC positive for improved print quality. The fuser bias
circuit is located in the high-voltage power supply, HVPS (T).
Fuser control
The DC controller and components in the fuser perform the following functions related to fuser operation:
●
Control fuser temperature
●
Detect fuser failures
●
Prevent excessive temperature rise
12 Chapter 1 Theory of operation ENWW