Samsung SCX-4521F Series Service Manual page 19

System Overview
3.1.1 Feeding section
There is a universal cassette which automatically loads paper and the manual feed which supplies paper
single sheet at a time. The cassette has a friction pad which separates paper to ensure single sheet
feeding, and it has a sensor, which checks when the paper tray is empty.
- Feeding Method: MP Cassette Type
- Feeding Standard: Center Loading
- Feeding Capacity: Cassette-150 sheets (75g/m2, 20lb paper standard)
- Paper detecting sensor: Photo sensor
- Paper size sensor: None
3.1.2 Transfer Ass'y
This consists of the PTL (pre-transfer lamp) and the Transfer Roller. The PTL shines a light onto the OPC
drum. This lowers the charge on the drum's surface and improves transfer efficiency.
The transfer roller transfers toner from the OPC drum surface to the paper.
- Life expectancy: Over 50,000 sheets (at 16~30°C)
3.1.3 Driver Ass'y
- Gear driven power unit. The motor supplies power to the paper feed unit, the fuser unit, and the toner
cartridge.
3.1.4 Fixing Part(Fuser)
- The fuser consists of the Heat Lamp, Heat Roller, Pressure Roller, Thermistor, and Thermostat. It fixes
toner to the paper using pressure and heat to complete the printing job.
3.1.4.1 Temperature-Intercepting Device (Thermostat)
The thermostat is a temperature sensing device, which cuts off the power to the heat lamp to prevent
overheating fire when the heat lamp or heat roller overheats.
3.1.4.2 Temperature Detecting Sensor (Thermistor)
The Thermistor detects the surface temperature of the heat roller, this information is sent to the main
processor which uses this information to regulate the temperature of the heat roller.
3.1.4.3 Heat Roller
The surface of the Heat Roller is heated by the Heat Lamp. As the paper passes between the Heat and
Pressure rollers the toner is melted and fixed permanently to the paper. The surface of the roller is coated
with Teflon. This ensures that toner does not adhere to the roller surface.
Service Manual
3-2
Manual 1 sheet (Paper, OHP, Envelop, etc.)
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