Samsung ML-2850D, ML-2851ND Service Manual

DIGITAL LASER PRINTER The keynote of Product

Smallest Duplex Built-in Mono Laser Printer (Low Noise)

- 28ppm(A4) / 30ppm(Ltr)

- PCL6, PS3, 1,200x1,200dpi

- 400MHz processor

- USB 2.0, N/W (ML-2851ND only)

- 32MB (Max.160MB : factory option)

- 2K Standard, 5K High Yield

- Paper Input: 250 sh CST + 1 sh MP

- Standard Duplex Printing

- Options: 250 sh SCF

ML-2850D

Manual

SERVICE

DIGITAL LASER PRINTER

ML-2850 Series

ML-2850D / ML-2851ND

Basic Model :ML-2851ND

ML-2851ND/XAZ

1. Precautions

1.1 Safety Warning 1-1

1.2 Caution for safety

1-2

1.3 ESD Precautions

1-5

2. Product spec and feature

2.1 Product Specifications 2-1

2.1.1 Product Overview

2-1

2.1.2 Specifications

2-1

2.1.3 Model Comparison Table

2-7

2.2 Summary of Product

2-9

2.2.1 Printer Components

2-9

2.2.2 System Layout

2-12

2.2.3 Engine H/W Specifications

2-17

2.2.4 S/W Descriptions

2-27

3. Disassembly and Reassembly

3.1 General Precautions on Disassembly 3-1

3.2 Used Screw List

3-2

3.3 Cover Unit

3-3

3.3.1 CASSETTE & Front Cover

3-3

3.3.2 DUPLEX UNIT & COVER-TOP/COVER-REAR

3-4

3.3.3 Cover-Side-LEFT/RIGHT

3-5

3.4 Fuser Ass'y

3-6

3.5 LSU(Laser Scanning Unit)

3-7

3.6 Drive Ass'y

3-8

3.7 Main PBA/SMPS/HVPS

3-9

3.8 HOLDER-PAD Disassembly

3-10

Contents

3.9 Transfer Roller 3-11

4. Alignment & Troubleshooting

4.1 Alignment and Adjustments 4-1

4.1.1 Sample Pattern

4-1

4.1.2 Control Panel

4-4

4.1.3 Consumables and Replacement Parts

4-7

4.1.4 LED Status Error Message

4-7

4.1.5 Abnormal Image Printing and Defective Roller

4-8

4.1.6 How to use DCU

4-9

4.1.7 Paper Jam

4-15

4.1.8 Download & Reset F/W

4-20

4.2 Troubleshooting

4-21

4.2.1 Procedure of Checking the Symptoms

4-21

4.2.2 The cause and solution of Bad image

4-22

4.2.3 The cause and solution of the bad discharge

4-38

4.2.4 The cause and solution of the malfunction

4-46

4.2.5 Toner Cartridge Service

4-56

4.2.6 The cause and solutions of bad environment of the software 4-58

5. Exploded Views & Parts List

5.1 Main 5-2

5.2 Top Cover

5-4

5.3 Cover Ass'y

5-6

5.4 Front Cover

5-8

5.5 Rear Cover

5-10

5.6 Frame

5-12

5.7 Main Drive

5-17

5.8 Rear Guide

5-19

Continued

5.9 Fuser 5-21

5.10 Duplex Unit

5-23

5.11 Cassette

5-25

5.12 SCF

5-27

6. System Diagram

6.1 Block Diagram 6-1

6.2 Connection Dia ram

6-2

7. Reference Information

7.1 Tool for Troubleshooting 7-1

7.2 Acronyms and Abbreviations

7-2

7.3 Select a location for the printer

7-4

7.4 Sample Tests Patterns

7-5

7.5 LAN (Optional Function)

7-6

7.6 Information of model's code

7-6

7.7 Parts Life Cycle Maintenance Table

7-7

7.7.1 Parts Life Cycle Maintenance Table

7-7

7.7.2 Toner Cartridge Criterion

7-7

7.8 Model Information

7-8

7.8.1 Understanding for Model Code

7-8

7.8.2 Understanding Material Code & Name

7-9

Continued

Service Manual

Precautions

1-1

Samsung Electronics

1. Precautions

In order to prevent accidents and to prevent damage to the equipment please read the precautions listed below carefully before servicing the printer and follow them closely.

1.1 Safety Warning

(1) Only to be serviced by appropriately qualified service engineers.

High voltages and lasers inside this product are dangerous. This printer should only be serviced by a suitably trained and qualified service engineer.

(2) Use only Samsung replacement parts

There are no user serviceable parts inside the printer. Do not make any unauthorized changes or additions to the printer, these could cause the printer to malfunction and create electric shock or fire hazards.

(3) Laser Safety Statement

The Printer is certified in the U.S. to conform to the requirements of DHHS 21 CFR, chapter 1 Subchapter J for Class 1(1) laser products, and elsewhere, it is certified as a Class I laser product conforming to the requirements of IEC 825. Class I laser products are not considered to be hazardous. The laser system and printer are designed so there is never any human access to laser radiation above a Class I level during normal operation, user maintenance, or prescribed service condition.

Warning >> Never operate or service the printer with the protective cover removed from Laser/Scanner assembly. The

reflected beam, although invisible, can damage your eyes. When using this product, these basic safety pre-cautions should always be followed to reduce risk of fire, electric shock, and injury to persons.

CAUTION - INVISIBLE LASER RADIATION 

WHEN THIS COVER OPEN.  DO NOT OPEN THIS COVER.

VORSICHT - UNSICHTBARE LASERSTRAHLUNG, 

WENN ABDECKUNG GEÖFFNET.  NICHT DEM STRAHL AUSSETZEN.

ATTENTION - RAYONNEMENT LASER INVISIBLE EN CAS 

D’OUVERTURE. EXPOSITION DANGEREUSE  AU FAISCEAU.

ATTENZIONE - RADIAZIONE LASER INVISIBILE IN CASO DI 

APERTURA. EVITARE L’ESPOSIZIONE AL  FASCIO.

PRECAUCION - RADIACION LASER IVISIBLE CUANDO SE ABRE. 

EVITAR EXPONERSE AL RAYO.

ADVARSEL. - USYNLIG LASERSTRÅLNING VED ÅBNING, NÅR 

SIKKERHEDSBRYDERE ER UDE AF FUNKTION.  UNDGÅ UDSAETTELSE FOR STRÅLNING.

ADVARSEL. - USYNLIG LASERSTRÅLNING NÅR DEKSEL 

ÅPNES. STIRR IKKE INN I STRÅLEN.  UNNGÅ EKSPONERING FOR STRÅLEN.

VARNING - OSYNLIG LASERSTRÅLNING NÄR DENNA DEL 

ÄR ÖPPNAD OCH SPÄRREN ÄR URKOPPLAD.  BETRAKTA EJ STRÅLEN. STRÅLEN ÄR FARLIG.

VARO! - AVATTAESSA JA SUOJALUKITUS OHITETTAESSA 

OLET ALTTIINA NÄKYMÄTTÖMÄLLE LASER- SÄTEILYLLE ÄLÄ KATSO SÄTEESEEN.

Service Manual

Precautions

1-2

Samsung Electronics

1.2 Caution for safety

1.2.1 Toxic material

This product contains toxic materials that could cause illness if ingested.

(1) If the LCD control panel is damaged it is possible for the liquid inside to leak. This liquid is toxic. Contact with the skin

should be avoided, wash any splashes from eyes or skin immediately and contact your doctor. If the liquid gets into the mouth or is swallowed see a doctor immediately.

(2) Please keep toner cartridges away from children. The toner powder contained in the toner cartridge may be harmful

and if swallowed you should contact a doctor.

1.2.2 Electric Shock and Fire Safety Precautions

Failure to follow the following instructions could cause electric shock or potentially cause a fire.

(1) Use only the correct voltage, failure to do so could damage the printer and potentially cause a fire or electric

shock.

(2) Use only the power cable supplied with the printer. Use of an incorrectly specified cable could cause the cable

to overheat and potentially cause a fire.

(3) Do not overload the power socket, this could lead to overheating of the cables inside the wall and could lead to

a fire.

(4) Do not allow water or other liquids to spill into the printer, this can cause electric shock. Do not allow paper

clips, pins or other foreign objects to fall into the printer these could cause a short circuit leading to an electric shock or fire hazard..

(5) Never touch the plugs on either end of the power cable with wet hands, this can cause electric shock. When

servicing the printer remove the power plug from the wall socket.

(6) Use caution when inserting or removing the power connector. The power connector must be inserted com-

pletely otherwise a poor contact could cause overheating possibly leading to a fire. When removing the power connector grip it firmly and pull.

(7) Take care of the power cable. Do not allow it to become twisted, bent sharply round corners or other wise

damaged. Do not place objects on top of the power cable. If the power cable is damaged it could overheat and cause a fire or exposed cables could cause an electric shock. Replace a damaged power cable immediately, do not reuse or repair the damaged cable. Some chemicals can attack the coating on the power cable, weakening the cover or exposing cables causing fire and shock risks.

(8) Ensure that the power sockets and plugs are not cracked or broken in any way. Any such defects should be

repaired immediately. Take care not to cut or damage the power cable or plugs when moving the machine.

(9) Use caution during thunder or lightening storms. Samsung recommends that this machine be disconnected

from the power source when such weather conditions are expected. Do not touch the machine or the power cord if it is still connected to the wall socket in these weather conditions.

(10) Avoid damp or dusty areas, install the printer in a clean well ventilated location. Do not position the machine

near a humidifier. Damp and dust build up inside the machine can lead to overheating and cause a fire.

(11) Do not position the printer in direct sunlight. This will cause the temperature inside the printer to rise possibly

leading to the printer failing to work properly and in extreme conditions could lead to a fire.

(12) Do not insert any metal objects into the machine through the ventilator fan or other part of the casing, it could

make contact with a high voltage conductor inside the machine and cause an electric shock.

Service Manual

Precautions

1-3

Samsung Electronics

1.2.3 Handling Precautions

The following instructions are for your own personal safety, to avoid injury and so as not to damage the printer

(1) Ensure the printer is installed on a level surface, capable of supporting its weight. Failure to do so could cause

the printer to tip or fall.

(2) The printer contains many rollers, gears and fans. Take great care to ensure that you do not catch your fingers,

hair or clothing in any of these rotating devices.

(3) Do not place any small metal objects, containers of water, chemicals or other liquids close to the printer which if

spilled could get into the machine and cause damage or a shock or fire hazard.

(4) Do not install the machine in areas with high dust or moisture levels, beside on open window or close to a

humidifier or heater. Damage could be caused to the printer in such areas.

(5) Do not place candles, burning cigarettes, etc on the printer, These could cause a fire.

1.2.4 Assembly / Disassembly Precautions

Replace parts carefully, always use Samsung parts. Take care to note the exact location of parts and also cable routing before dismantling any part of the machine. Ensure all parts and cables are replaced correctly. Please carry out the following procedures before dismantling the printer or replacing any parts.

(1) Check the contents of the machine memory and make a note of any user settings. These will be erased if the

mainboard or network card is replaced. (2) Ensure that power is disconnected before servicing or replacing any electrical parts. (3) Disconnect printer interface cables and power cables. (4) Only use approved spare parts. Ensure that part number, product name, any voltage, current or temperature

rating are correct. (5) When removing or re-fitting any parts do not use excessive force, especially when fitting screws into plastic. (6) Take care not to drop any small parts into the machine.

Service Manual

Precautions

1-4

Samsung Electronics

1.2.5 Disregarding this warning may cause bodily injury

(1) Be careful with the high temperature part.

The fuser unit works at a high temperature. Use caution when working on the printer. Wait for the fuser to cool

down before disassembly.

(2) Do not put finger or hair into the rotating parts.

When operating a printer, do not put hand or hair into the rotating parts (Paper feeding entrance, motor, fan, etc.). If do, you can get harm.

(3) When you move the printer.

This printer weighs 7.87kg. Use safe lifting and handling techniques. Use the lifting handles located on each side of the machine. Back injury could be caused if you do not lift carefully.

(4) Ensure the printer is installed safely.

The printer weighs 7.87Kg, ensure the printer is installed on a level surface, capable of supporting its weight. Failure to do so could cause the printer to tip or fall possibly causing personal injury or damaging the printer.

(5) Do not install the printer on a sloping or unstable surface. After installation, double check that the printer is stable.

17.35 Ibs.

7.87 Kg

Service Manual

Precautions

1-5

Samsung Electronics

1.3 ESD Precautions

Certain semiconductor devices can be easily damaged by static electricity. Such components are commonly called “Electrostatically Sensitive (ES) Devices”, or ESDs. Examples of typical ESDs are: integrated circuits, some field effect transistors, and semiconductor “chip” components.

The techniques outlined below should be followed to help reduce the incidence of component damage caused by static electricity.

Caution >>Be sure no power is applied to the chassis or circuit, and observe all other safety precautions.

1. Immediately before handling a semiconductor component or semiconductor-equipped assembly, drain off any electrostatic charge on your body by touching a known earth ground. Alternatively, employ a commercially available wrist strap device, which should be removed for your personal safety reasons prior to applying power to the unit under test.

2. After removing an electrical assembly equipped with ESDs, place the assembly on a conductive surface, such as aluminum or copper foil, or conductive foam, to prevent electrostatic charge buildup in the vicinity of the assembly.

3. Use only a grounded tip soldering iron to solder or desolder ESDs.

4. Use only an “anti-static” solder removal device. Some solder removal devices not classified as “anti-static” can generate electrical charges sufficient to damage ESDs.

5. Do not use Freon-propelled chemicals. When sprayed, these can generate electrical charges sufficient to damage ESDs.

6. Do not remove a replacement ESD from its protective packaging until immediately before installing it. Most replacement ESDs are packaged with all leads shorted together by conductive foam, aluminum foil, or a comparable conductive material.

7. Immediately before removing the protective shorting material from the leads of a replacement ESD, touch the protective material to the chassis or circuit assembly into which the device will be installed.

8. Maintain continuous electrical contact between the ESD and the assembly into which it will be installed, until completely plugged or soldered into the circuit.

9. Minimize bodily motions when handling unpackaged replacement ESDs. Normal motions, such as the brushing together of clothing fabric and lifting one’s foot from a carpeted floor, can generate static electricity sufficient to damage an ESD.

Service Manual

Product spec and feature

2-1

Samsung Electronics

2.1.2 Specifications

Product Specifications are subject to change without notice. See below for product specifications.

2.1.2.1 General Print Engine

ITEM ML-2850D ML-2851ND

Engine Speed Simplex Up to 28 ppm in A4 (30 ppm in Letter) Up to 28 ppm in A4 (30 ppm in Letter)

Duplex Up to 14 ipm in A4 (14.5 ipm in Letter) Up to 14 ipm in A4 (14.5 ipm in Letter) Warmup time From Sleep 15 sec 15 sec FPOT From Ready 8.5 sec 8.5 sec

From Sleep less than 23.5 sec less than 23.5 sec Resolution - Up to 1,200 x 1,200 dpi effective output Up to 1,200 x 1,200 dpi effective output

2. Product specification and feature

2.1 Product Specifications

2.1.1 Product Overview

28ppm(A4) / 30ppm(Ltr)

PCL6, PS3, 1,200x1,200dpi

400MHz processor

USB 2.0, N/W

(ML-2851ND only)

32MB (Max.160MB : option)

ML-2850D/2851ND

Options:

- 250 sh SCF

2K Standard, 5K High Yield

Paper Input: 250 CST + 1 MP

Standard Duplex Printing (World Smallest)

Service Manual

Product spec and feature

2-2

Samsung Electronics

2.1.2.2 Controller & S/W

ITEM ML-2850D ML-2851ND

Processor Samsung 400 MHz Samsung 400 MHz Memory Std. 32 MB 32 MB

Max. 160MB(option) 160MB(option)

Printer Languages - PostScript3, PCL6, SPL, IBM ProPrinter, PostScript3, PCL6, SPL, IBM ProPrinter,

EPSON EPSON Fonts - 45 scalable, 1 bitmap, 136 PostScript3 fonts 45 scalable, 1 bitmap, 136 PostScript3 fonts Driver Default Driver SPL SPL

Install SPL, PCL6, PS3 SPL, PCL6, PS3 Supporting OS Windows 2000/XP(32/64bits)/Vista(32/ Windows 2000/XP(32/64bits)/Vista(32/

64bits)/2003 Server(32/64bits) 64bits)/2003 Server(32/64bits)

Various Linux OS: Various Linux OS:

- Red Hat 8~9, - Red Hat 8~9,

- Fedora Core 1~4 - Fedora Core 1~4

- Mandrake 9.2~10.1 - Mandrake 9.2~10.1

- SuSE 8.2~9.2 - SuSE 8.2~9.2

Mac OS 8.6~9.2 / 10.1~10.4 Mac OS 8.6~9.2 / 10.1~10.4

WHQL Windows 2000, XP, 2003 Server, Windows 2000, XP, 2003 Server,

Vista(32/64bits) Vista(32/64bits)

Compatibility SPL & PCL6 : Win 2000/XP(32/64bits)/ SPL & PCL6 : Win 2000/XP(32/64bits)/

2003 server/Vista(32/64bits) 2003 server/Vista(32/64bits)

PS3: Win 2000/XP(32/64bits)/ PS3: Win 2000/XP(32/64bits)/

Vista(32/64bits)/ Vista(32/64bits)/

2003 PPD, Mac PPD, Linux PPD 2003 PPD, Mac PPD, Linux PPD Wired Network Protocol N/A SPX/IPX, TCP/IP, Ethertalk, SNMP, HTTP 1.1

Supporting OS N/A Windows NT4.0/2000/XP(32/64bits)/2003

Server/Vista(32/64bits)NetWare 5.x, 6.x Mac OS 8.6~9.2, 10.1~10.4 Various Linux OS including Red Hat 8~9, Fedora Core 1~4, Mandrake 9.2~10.1, and SuSE 8.2~9.2Unix HP-UX

Wireless Network Protocol N/A N/A

Supporting OS N/A N/A

Application Smart Panel SmartPanel for Windows/ Macintosh/LINUX SmartPanel for Windows/ Macintosh/LINUX

Printer Setting PSU for Windows/ Macintosh/LINUX PSU for Windows/ Macintosh/LINUX Network Management N/A SyncThru Web Admin Service 4.0 IP Setting N/A SetIP

Interface

Parallel - N/A N/A USB - Hi-Speed USB 2.0 Hi-Speed USB 2.0 Wired Network - N/A Ethernet 10/100 Base TX (Internal) Wireless Network - N/A N/A

User Interface

LCD - N/A N/A LED - 2 LED, 1 Key 2 LED, 1 Key Key - 1 Key (Demo, Stop) 1 Key (Demo, Stop)

Service Manual

Product spec and feature

2-3

Samsung Electronics

2.1.2.3 Paper Handling

ITEM ML-2850D ML-2851ND

Standard Capacity - 250-sheet Cassette Tray, 1-sheet Multi 250-sheet Cassette Tray, 1-sheet Multi

Purpose Tray @80g/

Purpose Tray @80g/ Max. Capacity - 501 sheets @ 80g/ 501 sheets @ 80g/ Printing Max. Size 216 x 356 mm (8.5" x 14") 216 x 356 mm (8.5" x 14")

Min. Size 76 x 127 mm (3.0" x 5.0") 76 x 127 mm (3.0" x 5.0")

Multi-purpose tray

Capacity Plain Paper 1 sheets @ 80g/

1 sheets @ 80g/

Envelope 1 sheets @75g/ 1 sheets @75g/

Media sizes - A4, A5, A6, Letter, Legal, Folio, Oficio, A4, A5, A6, Letter, Legal, Folio, Oficio,

Executive,ISO B5, JIS B5, 3"x5", Monarch, Executive,ISO B5, JIS B5, 3"x5", Monarch, No.10, DL, C5, C6 No.10, DL, C5, C6

Media type - Plain Paper, Transparency, Envelope, Plain Paper, Transparency, Envelope,

Labels, Post Card, Card stock Labels, Post Card, Card stock

Media weight - 16~43lb (60 to 163g/

) 16~43lb (60 to 163g/ )

Sensing - N/A N/A

Standard Cassette Tray

Capacity - 250 sheets @ 80g/

250 sheets @ 80g/ Media sizes - A4, A5, Letter, Legal, Executive, Folio, A4, A5, Letter, Legal, Executive, Folio,

Oficio, ISO B5, JIS B5 Oficio, ISO B5, JIS B5 Media types - Plain paper Plain paper Media weight - 16~28lb (60 to 105g/

) 16~28lb (60 to 105g/ )

Sensing - Paper empty sensor Paper empty sensor

Optional Cassette Tray

Capacity - 250 sheets @ 80g/

250 sheets @ 80g/

Media sizes - A4, A5, Letter, Legal, Executive, Folio, A4, A5, Letter, Legal, Executive, Folio,

Oficio, ISO B5, JIS B5 Oficio, ISO B5, JIS B5 Media types - Plain paper Plain paper Media weight - 16~28lb (60 to 105g/

) 16~28lb (60 to 105g/ )

Sensing - Paper empty sensor Paper empty sensor

Output Stacking

Capacity Face-Down 150 sheets @ 75g/

150 sheets @ 75g/

Face-Up N/A N/A

Output Full sensing - N/A N/A

Duplex

Supporting - Built-in Built-in Media sizes - A4, Letter, Legal, Folio, Oficio A4, Letter, Legal, Folio, Oficio Media types - Plain Paper Plain Paper Media weight - 20~24lb (75 to 90g/

) 20~24lb (75 to 90g/ )

Printable Area

Non-Printable Area Envelope 10mm(0.4") from edge(Top, Bottom, Left, 10mm(0.4") from edge(Top, Bottom, Left,

Right) Right)

Other Media 4mm(0.16") from edge(Top, Bottom, Left, 4mm(0.16") from edge(Top, Bottom, Left,

Right) Right)

Service Manual

Product spec and feature

2-4

Samsung Electronics

2.1.2.5 Reliability & Service

2.1.2.4 Consumables

ITEM ML-2850D ML-2851ND

Toner Black Standard: Average Cartridge Yield 2K Standard: Average Cartridge Yield 2K

standard pages. standard pages. High Yield: Average cartridge Yield 5K High Yield: Average cartridge Yield 5K standard pages. standard pages. Declared cartridge yield in accordance with Declared cartridge yield in accordance with

ISO/IEC 19752. ISO/IEC 19752. Key Electronic key(CRUM) Only Electronic key(CRUM) Only Life detect Toner gauge sensor by dot count Toner gauge sensor by dot count

Drum Yield N/A N/A

ITEM ML-2850D ML-2851ND

Max. Monthly Duty - 50,000 sheets 50,000 sheets MPBF - 35,000 sheets 35,000 sheets MTTR - 30 min. 30 min. SET Life Cycle - 100,000 sheets or 5 years 100,000 sheets or 5 years

(whichever comes first) (whichever comes first)

RDS Comm. Mode Ye s Ye s

Operation Ye s Ye s

2.1.2.6 Environment

ITEM ML-2850D ML-2851ND

Operating Temperature 10C to 32C 10C to 32C Environment Humidity 20% to 80% 20% to 80% Acoustic Noise Printing Less than 50dBA Less than 50dBA Level(Sound Standby Less than 26.0 dBA Less than 26.0 dBA Power/Pressure) Sleep Back Ground Level Back Ground Level Power Consumption Ready Less than 60W Less than 60W

AVG. Less than 400W Less than 400W Sleep / Power Off Less than 8W / Less than 0.4W Less than 8W / Less than 0.4W

(Conformity to EPA) (Conformity to EPA)

Dimension SET 364 x 369 x 209.6 mm 364 x 369 x 209.6 mm (W x D x H) (14.33" x 14.523" x 8.25 ") (14.33" x 14.523" x 8.25 ")

Weight SET 7.87 Kg 7.87 Kg

Service Manual

Product spec and feature

2-5

Samsung Electronics

2.1.2.8 Options

2.1.2.7 Packing & Accessory

ITEM ML-2850D ML-2851ND

In-Box - Driver & Network Install CD-ROM Driver & Network Install CD-ROM

Power Cable Power Cable USB Cable (CIS/China/Korea/India) USB Cable (CIS/China/Korea/India) Quick Install Guide Quick Install Guide Warranty Registration Card Warranty Registration Card User's Manual (PDF File) User's Manual (PDF File)

ITEM ML-2850D ML-2851ND

Memory Option (128MB) Option (128MB) Second Cassette - 250-sheet Cassette Tray 250-sheet Cassette Tray Wired Network - N/A N/A (Built-in) Wireless Network - N/A N/A Hard Disk - N/A N/A Duplex Unit - Standard Standard

2.1.2.9 Others

ITEM ML-2850D ML-2851ND

Memory Upgradable Mem. Slot N/A N/A

Upgradable Mem. Type N/A N/A Upgradable Mem. Unit 128MB(option) 128MB(option)

Sensor Paper Empty YES YES

Paper Size NO NO Media Type NO NO Paper Full NO NO

Service Service Item & Period 1. Transfer Roller : 50K pages 1. Transfer Roller : 50K pages

2. Fuser Unit : 50K pages 2. Fuser Unit : 50K pages

3. Pick-up Roller : 50K pages 3. Pick-up Roller : 50K pages

Certification Power FCC Part 15 Class B FCC Part 15 Class B

ICES-003 ICES-003 EN55022 Class B EN55022 Class B

Performance Jam Rate Base Line Paper : 1/5K Base Line Paper : 1/5K

Standard Paper : 1/2.5K Standard Paper : 1/2.5K

Stress Paper : 1/1500 Stress Paper : 1/1500 Speed Be equal or better than E250DN Be equal or better than E250DN Resolution Be equal or better than E250DN Be equal or better than E250DN

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Product spec and feature

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Samsung Electronics

2.1.2.10 Reliability & Service

* Periodic Replacing Parts

Code Fig.

JC66-01218A

JC97-03062A

JC96-04717A(220V) JC96-04718A(110V)

Yield (pages)PartsNo. Code Fig. Yield (pages)PartsNo.

50,000Transfer Roller1

50,000Pick-up Roller2

50,000Fuser Unit3

Service Manual

Product spec and feature

2-7

Samsung Electronics

2.1.3 Model Comparison Table

2.1.3.1 SEC Model

Samsung Samsung

ML-2851ND ML-2250

Image

Print Speed 28 ppm/A4 20 ppm/A4 Resolution 1,200 dpi class 600 dpi class Processor 400 MHz 166 MHz Memory (Max.) 32 MB (160 MB) 16 MB (144 MB) Emulation PCL6, PS3 PCL6 Interface USB 2.0, N/W USB 2.0, N/W IEEE1284 Paper Input 150 CST 150 CST FPOT (C/M) 30 sec/8.5 sec 50 sec/10 sec Noise 50 dBA 51 dBA Toner 2K/5K 3K/5K Dim. (WDH) 364 x 369 x 209.6mm 358 x 452 x 278mm Options 250 SCF, Memory (factory option) 250 SCF, Memory

Service Manual

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Samsung Electronics

2.1.3.2 Competitor Model

Samsung Brother Lexmark

ML-2851ND HL-5240 E250D

Image

Print Speed 28 ppm/A4 30 ppm/Ltr 30 ppm/Ltr Resolution 1,200 dpi class 1,200 dpi class 600 x 600 dpi Processor 400 MHz 264 MHz 300 MHz Memory (Max.) 32 MB (160 MB) 16 MB (16 MB) 64 MB (576 MB) Emulation PCL6,PS3 PCL6,PS3 PCL6,PS3 Interface USB 2.0, N/W USB 2.0, N/W USB 2.0, N/W Paper Input 250 CST 250 OT 250 CST FPOT (C/M) 30 sec/8.5 sec 20 sec N/A Noise 50 dBA 47 dBA N/A Toner 2K/5K 2K/2.5K 1K/2K Dim. (WDH) 364 x 369 x 209.6mm 407 x 453 x 370mm 420 x 424 x 432mm Options 250 SCF, 250 SCF 250/500 SCF,

Memory (factory option) Memory

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Samsung Electronics

2.2 Summary of Product

This chapter describes the functions and operating principal of the main component.

2.2.1 Printer Components

2.2.1.1 Front View

* The figure above shows an ML-2851ND.

1 output tray 6 tray 1

2 control panel 7 optional tray 2

3 control board cover 8 paper level indicator

4 front cover 9 output support

5 manual tray 10 manual tray paper width guides

Service Manual

Product spec and feature

2-10

Samsung Electronics

2.2.1.2 Rear View

* The figure above shows an ML-2851ND.

1 network port

4 duplex unit

2 USB port 5 power receptacle

3 optional tray 2 cable connector 6 power switch

a. ML-2851ND only.

Service Manual

Product spec and feature

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Samsung Electronics

2.2.1.3 Control Panel

1 Error: Indicates the status of your printer.

2 Online: Indicates the status of your printer.

3 Cancel: Prints a demo page or configuration page.

Cancels the print job. Makes the printer pick up the print media.

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Samsung Electronics

2.2.2 System Layout

FUSER

LSU

DEVE

DUPLEX

CASSETTE

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2.2.2.1 Feeding

It is consists of a basic cassette, an MP tray for supplying different types of media (envelope, label, special paper) duplex unit, and parts related to paper transferring.

1) Separation method

Separate it from the friction pad mounted to the center of the cassette.

2) Basic cassette

It takes a center loading method and applies 'friction pad separating method.' Both the side guide and the rear guide can be adjusted for for various types of papers from A5 to legal size paper. It has a paper existence sensing function (Capacity: 250 sheets of general paper), paper arranging function, various size papers accepting function, SCF paper path function, and displaying function of paper remaining amount. In the front side, there is a paper level indicator.

3) Pick-up roller

It has functions such as a paper pickup function, driving control function, paper feeding function, and removing electronic static function.

4) Registration roller

It has a paper arranging function, paper transferring function, paper detecting function, jam removing function, and so on.

5) MP tray

It has a paper arranging function, paper transferring function, jam removing function, and so on. It uses rubbing pad method to feed 1 sheets of general papers and 1 envelops.

6) Duplex unit

It has paper transferring function, paper guide function, jam removing function, paper sensing function, and main board supporting function. It is designed for basic attachment, and the duplex feeding takes a side feeding method. Usable papers are A4, letter, and legal size paper. For removing a jam occurred in a front part, it is designed to open a cassette and a guide. It is designed to open a rear cover to remove a jam in a rear part.

7) SCF (Second Cassette Feeder)

It is the same method with the main cassette, and the capacity is 250 sheets. It has a separate driving mechanism. It is designed for a common use with a main cassette.

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2.2.2.2 Transfer

A transfer roller transfers toner on an OPC drum to the paper. Life span: Print over 50,000 sheets (In 16~27 )

2.2.2.3 Driver Ass'y

By driving the motor, the system takes power. It consists of a main motor for feeding fuser and duplex reverse turn.

- Main Motor : DC 24V, Rated RPM : 2170rpm

2.2.2.4 Fuser

It is consisted of a heat lamp, heat roller, pressure roller, thermistor and thermostat. It sticks the toner on a paper by heat and pressure to complete the printing job.

- Halogen lamp : 750 Watt

1) Thermostat

When a heat lamp is overheated, a Thermostat cuts off the main power to prevent over-heating.

- Non-Cotact type Thermostat

2) Heat roller

The heat roller transfers the heat from the lamp to apply a heat on the paper. The surface of a heat roller is coated with Teflon, so toner does not stick to the surface.

3) Pressure roller

A pressure roller mounted under a heat roller is made of a silicon resin, and the surface also is coated with Teflon. When a paper passes between a heat roller and a pressure roller, toner adheres to the surface of a paper permanently.

4) Items for safety

Protecting device for overheating

- 1st protection device: Hardware cuts off when overheated

- 2nd protection device: Software cuts off when overheated

- 3rd protection device: Thermostat cuts off main power.

Safety device

- A fuser power is cut off when a front cover is opened

- Maintain a temperature of fuser cover's surface under 80(C for user, and attach a caution label at where customer can see easily when customer open a rear cover.

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2.2.2.5 LSU (Laser Scanner Unit)

It is the core part of the LBP which switches from the video data received to the controller to the electrostatic latent image on the OPC drum by controlling laser beam, exposing OPC drum, and turning principle of polygon mirror. The OPC drum is turned with the paper feeding speed. The /HSYNC signal is created when the laser beam from LSU reaches the end of the polygon mirror, and the signal is sent to the controller. The controller detects the /HSYNC signal to adjust the vertical line of the image on paper. In other words, after the /HSYNC signal is detected, the image data is sent to the LSU to adjust the left margin on paper. The one side of the polygon mirror is one line for scanning.

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Samsung Electronics

2.2.2.6 Print Cartridge

By using the electronic photo process, it creates a visual image. In the print cartridge, the OPC unit and the toner cartridge unit are in a body. The OPC unit has OPC drum and charging roller, and the toner cartridge unit has toner, supply roller, developing roller, and blade (Doctor blade)

- Developing Method: Non-contacting method

- Toner : Non magnetic 1 component pulverized type toner

- The life span of toner : 2,000 or 5,000 pages (LSA Pattern/A4 standard)

- Toner remaining amount detecting sensor : Yes

- OPC Cleaning : Cleaning blade type

- Management of disusable toner : Collect the toner by using Cleaning Blade

- OPC Drum protecting Shutter : No

- Classifying device for toner cartridge : ID is classified by CRUM. except for initial cartridge.

Cleaning Roller

Cleaning Blade

-750V

0.32mW

-250V

-1.25KV ~ -1.45KV

= -430V

VS = -680V

+4.2kV

-130V

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2.2.3 Engine H/W Specifications

2.2.3.1 Main Board

The Engine Board and the Controller Board are in one united board, and it is consisted of CPU part and print part in functional aspect. The CPU is functioned as the bus control, I/O handling, drivers, and PC interface. The main board sends the Current Image of Video data to the LSU and manages the conduct of Electrophotography for printing. It is consisted of the circuits of the motor (paper feed, pass) driving, clutch driving, pre-transfer lamp driving, current driving, and fan driving. The signals from the paper feed jam sensor and paper empty sensor are directly inputted to the main board.

SDRA

HVPS CN4

( 24V : 13 14

24VS : 9 10 )

U6, U7

Network

Interface & IC

EEPRO

U3, U4

SMPS CN10

( 24V : 4 6 8 10

5V : 12 14 16 )

ASIC

DC to DC

Converter

(3.3V) U15

DC to DC

Converter

(1.3V) U5

USB

Port &

NOR Flash

U17, U18

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2.2.3.1(a) Asic(SPGPv3)

CPU Core : ARM1020E

- 32KB instruction cache and 32KB data cache

Operating Frequency

- CPU Core : over 300MHz

- System Bus : 100MHz

SDRAMC

- 32Bits Only, 100MHz

- 5 Banks (Up to 128MB per Bank)

ROMC

- 4 Banks (Up to 16MB per Bank)

IOC

- 6 Banks (Up to 16MB per Bank

DMAC

- 4 Channels

HPVC

- Dual/Single Beam

- LVDS Pad(VDO, HSYNC)

UART

- 5 Channels (1 Channels Supports DMA Operation)

PCI Controller

- 32Bits, 33/66MHz

- PCI Local Bus Specification rev2.2 Complaint

- Host / Agent Mode (Support 4 Devices in Host Mode)

NAND Flash Controller

- 8/16Bits, H/W EEC Generation

- Auto Boot Mode (Using Internal SRAM, 4KB)

MAC

- 10M/100Mbps

- Full IEEE 802.3 Compatibility

Engine Controller

- LSU Interface Unit

- Step Motor : 2 Channels

- PWM : 8 Channels

- ADC : 6 Channels

I2C Controller

- I2C(S-BUS) Slave Device Support(I2C Version 2.1)

RTC

- RTC Core Voltage : 3V

PLL

- 3 PLL : MAIN, PCI, PVC

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2.2.3.1(b) Memory

Flash Memory : It stores System Program and downloads the System Program through PC Interface, and in case of model for export it compresses the PCL font, then stores it.

- Capacity : 16M Byte (NOR Flash)

- Random Access Time : 10 us (Max)

- Serial Page Access Time : 50ns (Min)

DRAM : It is used as Swath Buffer, System Working Memory Area, etc. when printing. It stores Font List, compressed into Flash memory, on DRAM and uses it as PCL font in case of model for export.

- Capacity : 32M Byte(Basic), up to 160Mbyte (Factory Option)

- Type : SDRAM 100MHz/133MHz , 32bit

2.2.3.1(c) Sensor Input Circuit

Paper Empty Sensing

The Paper empty sensor (Photo Interrupter) on the HVPS informs the state of paper to CPU whether it is empty or not with operation of the actuator. When cassette is empty, it detects the fact by reading the E20 of CPU, and then informs the fact by displaying the RED.

Paper Feeding/With Toner Cartridge Sensing

When paper passes the actuator (feed sensor part), it detects the signal of Photo interrupter, informs the paper feeding state to CPU, and then sprays the image data after certain time. If it doesn t detect the feed sensor within 1sec. after paper is fed, paper Jam0 is occurred (LED will be display Orange color). The fact whether the developer is inserted or not is detected by CRUM. After the developer is mounted, the subCRUM can read the information of toner cartridge from contact with CRUM involved in toner cartridge. If the information of toner cartridge is invalid, it will show invalid sign on LED.

Paper Exit Sensing

It detects paper state whether paper gets out from the set with operation of exit sensor on the HVPS and actuator on the frame. Paper detects the on/off time of exit sensor by reading D22 of CPU, and the normal operation or jam information is informed to the CPU. The paper JAM2 is informed. (LED will be display Orange color)

Cover Open Sensing

The Cover open sensor is located on the HVPS. After the front cover is opened, +24VS (DC fan, Solenoid, Main Motor, Polygon motor part of LSU and HVPS), which is supplied to the each unit, is cut off. The cover-open sensing is operated by the D23 of CPU. In case, the red will be ON for informing the facts to user.

DC FAN / SOLENOID Driving

It is driven by transistor and controlled by D14(FAN MAIN), E16(FAN DUPLEX), C23(PICK-UP CLUTCH), C18(REGI CLUTCH), D15(MPF CLUTCH) of CPU. When it is high, the fan is driving by turning on the TR, and it is off when the sleep mode is selected. There are three solenoids, and they are driven by paper pick-up, regi and MPF signal. It is turned on or off by C23, C18, D15 of CPU. The diode protects the driving TR from the noise pulse, which is flown when the solenoid id de-energizing. FAN Driving Circuit is driven by Transistor, and controlled by D14, E16 of CPU.

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Samsung Electronics

Motor Driving

The main motor driving circuits is on the BLDC Motor Ass y Unit. Main Controller has the interfacing circuits. There is motor driver IC on the motor control board of Motor Ass y Unit.

The exit motor driving circuits is formed when the driver IC is selected. The AN44060AMotor Driver IC is used in this case. The resistance Rs value for sensing and voltage value for the V reference can be changed by motor driving voltage value. The motor driving voltage is calculated with the following formula.

The motor driving circuit is formed when the Driver IC is selected. The A3977 Motor Driver IC is used in this case. The resistance Rs value for sensing and voltage value for the V reference can be changed by motor driving voltage value. The motor driving voltage is calculated with the following formula. I = Vref / Rs, wherein Vref is (R1 5V) / (R1+R2).

IN 0, 2 IN 1, 3 Output Current L L Vref / (10*Rs) = Iout H L Vref / (15*Rs) = Iout * 2/3 L H Vref / (30*Rs) = Iout * 1/3 H H 0

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Samsung Electronics

2.2.3.2 SMPS & HVPS board

The SMPS supplies DC Power to the System. It takes 110V/220V and outputs the +5V, +24V to supply the power to the main board. The HVPS board creates the high voltage of THV/MHV/Supply/Dev and supplies it to the developer part for making 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.

2.2.3.2(a) HVPS (High Voltage Power Supply)

Transfer High Voltage (THV+)

- Input Voltage : 24 V DC 15%

- Output Voltage : MAX +5.0KV 5 %,(Duty Variable, no loading )

->1.2KV 15% (when cleaning,200 )

- Output Voltage Trigger : 6.5

- Input contrast of the Voltage stability degree :under 5 % (fluctuating input 21.6V 26.4V) Loading contrast : 5 % or less

- Output Voltage Rising Time : 100 ms Max

- Output Voltage Falling Time : 100 ms Max

- Fluctuating transfer voltage with environmental various : +650 V(Duty 10%) ~ 5 KV (Duty 90%)

- 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 THVPWM Signal. 10% Duty : +650V, 90% Duty : +5KV 5%

Charge Voltage (MHV)

- Input Voltage : 24 V DC 15%

- Output Voltage : -1.3KV ~ -1.8KV DC 50V

- Output Voltage Rising Time : 50 ms Max

- Output Voltage Falling Time : 50 ms Max

- Output Loading range : 30 M ~ 1000 M

- Output Control Signal(MHV-PWM) : CPU is HV output when PWM is Low

Cleaning Voltage (THV-)

- The (+) Transfer Voltage is not outputted because the THV PWM is controlled with high.

- The (-) Transfer Voltage is outputted because the THV-Enable Signal is controlled with low

- The output fluctuation range is big because there is no Feedback control.

Developing Voltage (DEV)

- Input Voltage : 24 V DC 15%

- Output Voltage: -200V ~ -600V DC 20 V

- Output Voltage Fluctuation range: PWM Control

- Input contrast of the output stability degree : 5 % or less Loading contrast : 5 % or less

- Output Voltage Rising Time : 50 ms Max

- Output Voltage Falling Time : 50 ms Max

- Output Loading range : 10M ~ 1000 M

- Output Control Signal (BIAS-PWM) : the CPU output is HV output when PWM is low.

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