ML-2850D
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 avail-
able 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 assem-
bly.
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 dam-
age 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 compa-
rable conductive material.
7. Immediately before removing the protective shorting material from the leads of a replacement ESD, touch the pro-
tective 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 com-
pletely 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
Service Manual
Product spec and feature
2-6
Samsung Electronics
2.1.2.10 Reliability & Service
* Periodic Replacing Parts
JC96-04717A(220V)
JC96-04718A(110V)
JC97-03062A
JC66-01218A
Code Fig.
50,000Fuser Unit3
50,000Pick-up Roller2
50,000Transfer Roller1
Yield (pages)PartsNo. Code Fig. Yield (pages)PartsNo.
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
Product spec and feature
2-8
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
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2.2.1.2 Rear View
* The figure above shows an ML-2851ND.
1 network port
a
4 duplex unit
2 USB port 5 power receptacle
3 optional tray 2 cable connector 6 power switch
a. ML-2851ND only.
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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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2.2.2 System Layout
LSU
DEVE
CASSETTE
DUPLEX
FUSER
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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, spe-
cial 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 remov-
ing 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 func-
tion, 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
5%
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 electro-
static 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 con-
troller. 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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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
V
D
= -430V
V
S
= -680V
1
2
3
4
5
6
7
8
+4.2kV
-130V
+
-
<Toner Cartridge Layout>
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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
M
U6, U7
SDRA
M
U6, U7
ASIC
U8
ASIC
U8
USB
Port &
IC
USB
Port &
IC
Network
Interface & IC
Network
Interface & IC
DC to DC
Converter
(3.3V) U15
DC to DC
Converter
(3.3V) U15
DC to DC
Converter
(1.3V) U5
DC to DC
Converter
(1.3V) U5
NOR Flash
U17, U18
NOR Flash
U17, U18
EEPRO
M
U3, U4
EEPRO
M
U3, U4
SMPS CN10
( 24V : 4 6 8 10
5V : 12 14 16 )
SMPS CN10
( 24V : 4 6 8 10
5V : 12 14 16 )
HVPS CN4
( 24V : 13 14
24VS : 9 10 )
HVPS CN4
( 24V : 13 14
24VS : 9 10 )
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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 sub-
CRUM 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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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 volt-
age 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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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 sup-
plied 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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