Samsung SCX-4521F Operation Instruction & Installation

System Overview

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Service Manual

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3. System Overview

3.1 System Layout

The SCX-4521F/4321 is roughly made up Main Control part, Operation Panel part, Scanner part, Line
Interface part and Power part. Each Part is separated Module which focus on common and standard design
of different kind products. main control part adopting Fax & LBP Printer exclusive Controller is chorus2
CPU(ASIC) and 1 Board. Scanner part is composed of ADF and Platen and is connected with Main by
Harness.

ADF ROLLER

Scanner part

Engine Part

ADF-UPPER

PICK-UP ROLLER

EXIT ROLER

WHITE BAR

ADF-GLASS

FEED ROLLER

SCAN UPPERSCAN UPPERSCAN UPPER

ADF-LOWER

COVER OPEN

BIN PATH

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Service Manual

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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)
Manual 1 sheet (Paper, OHP, Envelop, etc.)

- 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.

System Overview

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Service Manual

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3.1.4.4 Pressure roller

The Pressure Roller mounted under the heat roller, it is made of a silicon resin, and the surface of the roller
is coated with Teflon. This ensures that toner does not adhere to the roller surface.

3.1.4.5 Safety Features

• To prevent overheating

- 1st protection device: Hardware cuts off when overheated

- 2nd protection device: Software cuts off when overheated

- 3rd protection device: Thermostat cuts off mains power to the lamp.

• Safety device

- Fuser power is cut off when the front cover is opened

- LSU power is cut off when the front cover is opened

- The temperature of the fuser cover's surface is maintained at less than 80°C to protect the user and a
caution label is attached where the customer can see it easily when the rear cover is opened.

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STACKER

COVER-M-SIDE R

EXTEND-SMALL

EXTEND-LARGE

TRAY CASSETTE

COVER-M_DEVE

FIXING BKT

SPEKER

COVER-M-SIDE-L

COVER-M_REAR

COVER-M_JAM

COVER-M_MIDDLE

SCAN

UPPER

MOTOR

ASS’Y

SCAN

LOWER

TIMING

BELT

CIS

SLIDER

-CIS

ADF

GLASS

SCAN

GLASS

KEY & OPE

COVER

[Case part figure]

[Scan part figure]

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3.2 Engine H/W Specification

1) Recording Method : LSU(Laser Scanning Unit)

2) Printing Speed : 20ppm
(In continuing printing base Letter, printing pages from 2nd to last during 1min)

3) Recording Density : 600 dpi

4) Cassette Capa. : Cassette ; 150sheets(75g/ Base), 1-sheet Feeding : N/A((DRIVE Selection : Paper, OHP,

Envelop - 1 sheet)

5) Manual Tray : All paper 1 sheet

6) Paper Size : Cassette ,Manual ; Width = 76 ~ 216mm, Length = 125mm ~ 356mm

7) Effective recording size

- A4 :202 x 291 mm

- Letter :208 x273mm

- Legal : 208 x 350 mm

- Folio : 208 x 325 mm

- TopMargin: 2 2 mm

- Left, Right Margin : 2

2 mm

8) CRU(Toner Cartridge)Life : 3,000pages Printing(A4, ISO 5% Pattern Printing)

9) First Print Out Time : within 11sec ( Standby )

10) Warming up time : within 35sec (Ambient : 25 °C)

3.2.1 Main Board Control Part

Main control part of SCX-4521F is made of ASIC(CPU, Image processor, PC I/F part include, Scan interface part,
FAX Modem part and Printing process I/F part. CPU handles the BUS control, I/O interface, scan interface, PC
interface and other miscellaneous driver circuit.

1) Main Board

- Main Board has a function of sending Current Image Video Data to LSU of the machine, controlling motor
Driving Circuit and monitoring Paper Exit Sensor, Cover Open switch, OPE Panel Inputs.

2) Main Controller

- CPU : Chorus2 is the main CPU and is made up on the 16/32bit RISC architecture using ARM7TDMI

core. Main CPU controls the whole system according to the program code which stored in the
Flash-ROM memory.

- Summary of the Key Function Block:

1.8V for internal Core, 3.3V for I/O Pad with 4KByte Cache.
Image Processor included.
On-Chip clock generator with PLL.
Memory and External Bank Control.
DMA Control (5-Channel)
Interrupt Control.
2-port USB Host/1-port USB device(ver 1.1) interface control.
Parallel interface control.
UART(2-Channel)