User Guide

Overcurrent/overvoltage
There are two overvoltage devices in this device:
●
Fuse F101 provides overcurrent protection for the fusing system circuitry.
●
Fuse F102 (110 V devices only) provides overcurrent protection to the device dc power supply
circuitry.
You can check or replace the fuses by removing the left cover.
NOTE If either of these fuses fail, replace the engine power supply. See Power supply
on page 91.
High-voltage power distribution
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. High voltage is disabled when the print-cartridge door is open.
The following figure shows this process.
50 Chapter 5 Theory of Operation ENWW