Phaser 3250 Laser Printer Service Manual 2-19
Theory of Operation
Transfer High Voltage (THV+)
The (+) Transfer High Voltage is supplied to the Transfer Roller for transferring
toner onto the OPC Drum to the paper.
■ Input Voltage: 24 VDC ± 15%
■ Output Voltage:
■ MAX +5.0KV ± 5% (duty variable, no loading)
■ -1.2KV ± 15% (when cleaning, 200 M Ω)
■ Output Voltage Trigger: 6.5 uA
■ Input Contrast of the Voltage Stability Degree: Under ± 3% (fluctuating
input 21.6 V ~ 26.4 V0
■ Loading Contrast: ± 5% or less
■ Output Voltage Rising Time: 50 ms Max
■ Output Voltage Falling Time: 100 ms Max
■ Fluctuating Transfer Voltage with Environmental Various: 0 ~ 5 KV
■ Environment Recognition Control Method: The THV-PWM ACTIVE is
transfer active signal. It detects the resistance by recognizing the voltage
value, F/B, while permits the environmental recognition voltage.
■ Output Voltage Control Method: Transfer Output Voltage is outputted
and controlled by changing Duty of THV/PWM signal.
Charge Voltage (MHV)
The High Voltage is supplied to the OPC Drum through the Charging Roller
while charging the skin of the OPC Drum.
■ Input Voltage: 24 VDC ± 15%
■ Output Voltage: -1.0 KV ~ -1.8 VDC ± 3%
■ Output Voltage Riding Time: 50 ms Max
■ Output Voltage Failing Time: 50 ms Max
■ Output Loading Range: 30 M Ω ~ 1000 M Ω
■ Output Control Signal (MHV-PWM): CPU is HV output when PWM is Low.
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