Samsung ML-1755, Service Manual, Page: 26 / 116

4-15
Samsung Electronics
S U M M A RY OF PRO D U C T
Training Manual
4.5 SMPS & HVPS
The SMPS supplies the DC power to the system.
It takes 110V/220V and outputs the +3.3V and +24V to supply the power to the main board and ADF board.
The HVPS part creates the high voltage of THV/MHV/Supply/Dev and supplies it to the developer part for
making the best condition to display the image. The HVPS part takes the 24V and outputs the high voltage
for THV/MHV/BIAS, and the outputted high voltage is supplied to the toner, OPC cartridge, and transfer
roller.
4.5.1 HVPS(High Voltage Power Supply)
1) Transfer High Voltage (THV+)
- Inputting voltage : 24 V DC ± 15%
- Outputting voltage : +5.0KV ± 5 %,(Duty 10% , %, no loading)
- 1.0KV ±15% (When cleaning,200 M
Ω
)
- Outputting voltage Trigger : 6.5 µA
- Inputting contrast of the Voltage stability degree : under ± 5% (fluctuating input 21.6V~26.4V)
Loading contrast : under ± 5%
- Outputting voltage Rising Time : 100 ms Max
- Outputting voltage Falling Time : 100 ms Max
- Fluctuating transfer voltage with environmental various : +650 V(Duty 10%) ~ 5 KV (Duty 90%)
- Environmental recognition Controlling method : The THV-PWM Active is transfer active signal. It
detects the resistance by recognizing the voltage
value, F/B, while permits the environmental recog-
nition voltage.
- Outputting voltage Controlling method : The transfer output voltage is outputted and controlled by
changing the duty of THVPWM signal.
10% Duty : +650V, 90% Duty : +5KV ± 5%
2) Charge Voltage (MHV)
- Inputting voltage : 24 V DC ± 15%
- Outputting voltage : -1.3KV ~ -1.8KV DC ± 50V
- Outputting voltage Rising Time : 50 ms Max
- Outputting voltage Falling Time : 50 ms Max
- Output loading range : 30 M
Ω
~ 1000 M
Ω
- Output controlling signal (MHV-PWM) : CPU output is high when the PWM is low
3)Cleaning Voltage (THV-)
- The (+) transfer voltage is not outputted because the THVPWM is controlled with high.
- The (-) transfer voltage is outputted because the THV-Enable signal is controlled with low.
- The outputting fluctuation range is big because there is no feedback control.
4) Developing Voltage (DEV)
- Inputting voltage : 24 V DC ± 15%
- Outputting voltage : -200V ~ -600V DC ± 20 V
- Outputting voltage fluctuating range : PWM control
- Inputting contrast of the output stability degree : under ± 5% Loading contrast : under ± 5%
- Output voltage rising time : 50ms Max
- Output voltage falling time : 50ms Max
- Output loading range : 10M•ÿ ~ 1000M
- Output controlling signal (BIAS-PWM) : the CPU output is high when PWM is low.