HP LASERJET ENTERPRISE MFP M725dn, Troubleshooting Manual

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High-voltage power-supply PCA
The high-voltage power supply applies positive or negative voltage biases to the following components:
●
Primary charging roller
●
Developing roller
●
Transfer roller
●
Static charge eliminator
●
Fuser film
Figure 1-7 High-voltage power-supply PCA
Fuser
Fuser film
Pressure roller
Transfer bias
circuit
Static charge eliminator
DC controller
Photosensitive drum
Transfer roller
High-voltage power supply
Primary
charging bias
circuit
Developing
bias circuit
Static charge
eliminatior
bias circuit
To primary charge roller
To developing roller
Cartridge
The DC controller controls the high-voltage power supply to generate the following biases.
●
Primary charging bias
The primary charging bias is used to charge the surface of the photosensitive drum evenly to
prepare for image formation. The primary charging bias circuit generates the bias.
●
Developing bias
The developing bias is used to adhere toner to an electrostatic latent image formed on the
photosensitive drum. The developing bias circuit generates the bias.
●
Transfer bias
The transfer bias is used to transfer the toner from the photosensitive drum onto the paper. The
transfer bias circuit generates the bias. The transfer bias circuit also generates the reverse bias to
clean the transfer roller.
14 Chapter 1 Theory of operation ENWW