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2.4 Power Supply Board
The power supply board consists of an AC filter circuit, a low voltage power supply circuit, a high
voltage power supply circuit, heater drive circuit, and photosensors.
(1) Low Voltage Power Supply Circuit
This circuit generates the following voltages.
Output voltage Use
+5 V Logic circuit supply voltage
+30 V Motor and fan drive voltage and source voltage for high-voltage supply
+8 V Analog supply voltage
–8 V PS board and analog circuit supply voltage
(2) High Voltage Power Supply Circuit
This circuit generates following voltages required for electrophotographic process from +5
V, according to the control sequence from the control board. When cover open state is
detected, +5 V supply is interrupted automatically to stop the supply of all high-voltage
outputs.
Output Voltage Use Remarks
CH -1.35 KV Voltage applied to charging roller
DB -300 V/+300 V Voltage applied to developing roller
SB -450 V/ 0 V Voltage applied to toner supply roller
TR +500 V to +4 KV/-750 V Voltage applied to transfer roller Variable
CB +400 V Voltage applied to clearing roller
(3) Photosensor
The photosensor mounted on this power supply board monitors the paper running state
during printing.
