HP laserjet 1018 Manuale Di Servizio

The engine-power assembly provides the ac, dc, and high-voltage power supply circuits.

The ac power circuitry supplies ac voltage whenever the power cord is connected to the ac power
source and the power switch is on. AC voltage is distributed to the dc power supply circuitry and to
the ac driver circuitry, which controls ac voltage to the fuser-assembly heating element.  

The dc power distribution circuitry, located on the engine-power assembly, distributes +3.3 Vdc,
+5 Vdc, and +24 Vdc as follows:

●

+3.3 Vdc

ECU, sensors, formatter

●

+5 Vdc

Parallel interface on the HP LJ 1015 printer formatter

●

+24 Vdc

Main motor, laser/scanner motor, solenoid, high-voltage power supply, fuser, safety
circuit, door switch

Two overvoltage devices are in this printer:

●

Fuse F101 provides overcurrent protection for the fusing-system circuitry.

●

Fuse F102 (110 V printers only) provides overcurrent protection to the printer dc power-supply
circuitry.

You can check or replace the fuses by removing the left cover. If either of these fuses fails, replace
the engine-power assembly.

The high-voltage power supply applies an overlap of dc and ac voltage to the primary-charging roller
and to the developing roller. This circuit also applies a positive or negative dc voltage to the transfer
roller according to the instructions from the engine-control unit.

This circuit also controls the image density by changing the primary ac voltage and the developing ac
bias according to the print-density setting. See 

The high-voltage power supply is disabled when the print-cartridge door is open.

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Chapter 4   Operational overview

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