2-20 Phaser 3250 Laser Printer Service Manual
Theory of Operation
Cleaning Voltage (THV-)
The (-) Transfer High Voltage is supplied to the Transfer Roller to remove the
remaining toner from the OPC Drum.
■ The (+) Transfer Voltage is not outputted because the THV PWM is
controlled with high.
■ The (-) Transfer Voltage is outputted because the THF-Enable Signal is
controlled with low.
■ The output fluctuation range is large because there is no feedback
control.
Developing Voltage (DEV)
The Developing Voltage is supplied to the Developer Roller to transfer to the
toner to the charge on the OPC Drum scanned by the laser beam while
printing the image. The engine controls whether the high voltage is supplied
and its quantity.
■ Input Voltage: 24 VDC ± 15%
■ Output Voltage: -200 V ~ 600 V DC ± 3%
■ Output Voltage Fluctuation Range: PWM Control
■ Input Contrast of the Output Stability Degree: ± 3% or less
Loading Contrast: ± 3% or less
■ Output Voltage Rising Time: 50 ms Max
■ Output Voltage Failing Time: 50 ms Max
■ Output Loading Range: 10 M Ω ~ 1000 M Ω
■ Output Control Signal (BIAS-PWM): The CPU output is HV output when
PWM is low.
Supply
■ Output Voltage: -400 C ~ 800 VDC ± 50 V (ZENER using, DEV)
■ Input Contrast of the Output Stability Degree: Under ± 5%
■ Loading Contrast: ± 5% or less
■ Output Voltage Rising Time: 50 ms Max
■ Output Voltage Failing Time: 50 ms Max
■ Output Loading Range: 10 M Ω ~ 1000 M Ω
■ Output Control Signal (BIAS-PWM): The CPU is HV output when PWM is
low.
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