Samsung ML-5000 Troubleshooting

4. Troubleshooting

4-1 Abnormal Image Printing and Defective Roller

If abnormal image prints periodically, check the parts shown below.

Samsung Electronics 4-1

No Roller Abnormal image period Kind of abnormal image

1 OPC Drum 94.3mm White spot
2 Charge Roller 37.7mm Black spot
3 Supply Roller 40.0mm Horizontal density band
4 Develop Roller 46.1mm Horizontal density band
5 Transfer Roller 47.1mm Black side contamination/transfer fault
6 Heat Roller 56.1mm Black spot and fuser ghost
7 Pressure Roller 56.2mm Black side contamination

Check connection to
computer or replace
controller.

Take out the cartridge
and prepare the tester
for electronic connection.

Repair or replace the GND
terminal.

Check the path between
video controller, engine board
and HVPS. Repair or replace
the defective component
or board.

The mirror in LSU might be misplaced so the light
path to the OPC deviates ->Repair or replace LSU
or remove any defective matters in the machine.

Self test

pattern prints?

No image?

Self testing

is possible via

DCU?

Is the OPC

terminal of machine

well-connected

to Frame?

Does the

video data line to

LSU transit to High/Low

when printing?

Re-test after replacing the
conector or controller board.

A on

next page

NO

NO

NO

NO

NO

YES

YES

YES

YES

YES

4-2 Print Quality

4-2-1 No Image

4-2 Samsung Electronics

Troubleshooting

Transfer roller might be out of its location.

-> Locate the roller into its place.

This could occurrs when the power of LSU is low or
the density is low due to the obstacles on the window

-> Replace LSU or clean the window.

A

Transfer

voltage OK? (on the

transfer roller

shaft)

Are the

connection terminal

and connection

correct?

Repair or replace terminal.

Sealing tape

is removed from the

cartridge?

Replace HVPS or repair defective component.

Is the connection

terminal OK?

Replace HVPS or repair
defective component.

Repair or replace terminal.

Remove the tape.

Developing

(-300V) and supplying

(-500V) voltage

are OK?

Does the

counter indicate over

the toner's guarranty

life?

Replace the toner cartridge.

NO

NO

NO

NO

NO

NO

YES

YES

YES

YES

YES

YES

4-3

Samsung Electronics

Troubleshooting

All black in

printing area?

Is transfer

voltage supplied

from HVPS?

Is the

Hsync/ signal received

in LSU?

Transfer part's contact
is bad. -> Repair or
replace toner cartridge.

Does the

video data line to LSU

transit to High/ Low when

printing?

Replace LSU.

Check the path among video
controller, engine board,
HVPS, LSU for the shortage
or open. -> Repair or replace
the boards.

Repair or replace HVPS.

Replace LSU.

NO

NO

NO

NO

YES

YES

YES

YES

4-2-2 All Black

4-4 Samsung Electronics

Troubleshooting

White line

missing definitely?

Dirt of dust stuck onto the
window of internal lens of LSU

-> Clean it or replace LSU.

Preventive obstacles through
the path between OPC of
developer and LSU prevent the
path -> Remove the obstacles.

Check if the

printout is still has the

same problem even right after

passed through the

transfer roller.

Toner material might be stuck to
blade in the developer inside and it
prevents toner supply -> Replace
the developer.

Check both if the toner cartridge's
counter is over its guaranty and
amount of the toner material.

-> Replace the toner cartridge.

The ribs in fuser or toner on the
roller may invoke the image
problem. -> Replace the fuser
cover or the defective part.

The image is originally black or the
black part is far close to the top.

-> Use the pattern which has the
image below bigger than 10mm
from the top.

NO

NO

YES

YES

4-2-3 Vertical White Line (Band)

4-5Samsung Electronics

Troubleshooting

'Dark' selected

via RCP?

Change to

'Normal' and test.

Works

correctly with

-300V of Bias
voltage?

Works

correctly after

replaced LSU?

Repair or replace the defective
component.

The power of LSU is set
high or internal problem.

-> Replace LSU or adjust
volume.

Same at 'Normal'?

END

NO

NO

NO

Toner over supply due to the
adjustment fault of metering
blade in developer.

-> Replace developer.

NO

YES

YES

YES

YES

4-2-4 Dark Image

4-6 Samsung Electronics

Troubleshooting

Recommended

paper used?

Transfer,

charge and developing

voltage are OK?

Operating/

storage atmosphere is

too high temperature

/humidity?

Solve the problem under
the recommended condition
(10-32 degree Centigrade).

Dirt or

dust around the

charge roller?

Clean the charge roller
or replace step-up device
/terminal after check.

Work OK?

Internal blade or
suppying part of the
developer is defective.

-> Replace the toner
cartridge.

Check terminals or contacts and 'Guide-Deve Spring'
are misplaced.

-> Repair or replace transfer roller etc.

Check if the LED of PTL in front of the transfer roller
is on when it presses the top cover switch on purpose.

-> If not, replace PTL.

Print 20 to 30 pages using
the recommended paper.

Same problem

occurs?

- Adjust voltage or
replace HVPS.

- Repair or replace
after checking the
terminals' contacts.

END

Replace the
toner cartridge.

NO

NO

NO NO

NO

NO

YES

YES

YES

YES

YES

YES

4-2-5 Background

4-7Samsung Electronics

Troubleshooting

YES

Is it regular

interval of 94mm?

PTL lamp

works OK?

Transfer

voltage is set to

standard?

Is it regular

interval of 46mm?

Is it regular

interval of 47mm?

(as transfer roller

interval)

Developing

/suppying voltage

normal? (-300V/

-500V)

Check HVPS
contacts and
HVPS's self­output.

-> If failed,
repair/replace
HVPS.

Replace PTL
assembly.

Irregularity of NIP
between rollers in
developer.

-> Replace developer.

- Repair or replace HVPS .

- Check and repair or
replace the terminal
contacts.

A specific part of the transfer
roller has ruined or its
resistance value is changed.

-> Replace transfer roller.

Transfer roller cannot force
regularly due to the gears
eccentricity of transfer roller.

-> Replace the defective
component.

Bias voltage

is OK? (-300V)

Operating/storage

temperature is too low or

not recommended

paper used?

Adjust the Bias
voltage or replace
HVPS.

There may be a problem in toner
layer control in toner cartridge.

-> Replace the developer.

Use the machine with
recommended paper and
at normal condition.

NO

NO

NO

NO

NO

NO

NO

YES

YES

YES

YES

YES

YES

YES

4-2-6 Ghost

4-8 Samsung Electronics

Troubleshooting

Is it regular

interval of 38mm?

The problem occured
since the obstacles
stuck to charge roller.

-> Replace developer
and C/R.

When taking

out the cartridge,

toner leaks?

Toner leaks and toner
material dropped onto
the paper. -> Replace the
developer.

Bad image

removes by

scratching?

Check toner is stuck onto
the P/R or H/R in fuser.

-> Clean it or replace.

The problem
randomly occured
due to the toner
fallen. -> Clean the
machine.

NO NO NO

YES

YES

YES

4-2-7 Black Dot

NO

Black band?

The black

band has regular

interval?

Black band

is far about 10mm from

white band?

Problem of internal
contacts in OPC.

-> Replace developer.

The OPC is damaged under the
direct sunlight for around 5
minutes. -> If the same problem
persists in 10 hours, replace
the developer.

This occurs when no
Hsync/ at LSU.

-> Replace LSU.

94mm interval?

Heat roller is ruined.

-> Replace the roller.

The OPC is damaged due to
the irregular transfer voltage
of HVPS.

-> Repair/replace HVPS.

-> If the same problem persists,
replace the developer.

Does it appear

at every 56.1mm at

specific place?

Problems of terminal contact,
transfer voltage supplying,
and transfer roller's due to the
charge roller is ruined (38mm).

-> Repair/replace HVPS,
developer.

NO

NO NO

NO

YES

YES

YES

YES

4-2-8 Horizontal Band

4-9Samsung Electronics

Troubleshooting

OK after

taking out and

rocking the toner

cartridge?

It is over the guaranty
life of toner cartridge.
(Check the counter
and replace it.)

When gray
pattern printing,
irregular density

persists?

PTL lamp

works OK?

Any obstacles

on the PTL lamp?

Transfer/

charge/developing

voltage drops while

printing?

Defective agitator in
the toner supplying part
of developer.

->Replace the developer.

Check if the 'guide deve
spring' works OK and
repair/repalce.

Check high voltage
output and repair/
replace terminals/HVPS.

Replace lamp.

Clean the window of PTL.

Bad images

aroung the no image

area?

Irregualrity of toner
suppy from developer.

-> Replace developer.

Light distortion due to
the mirror ruined or
LSU's diffused reflection.

-> Replace LSU.

NO

NO NO

NO

NO

NO

YES

YES

YES

YES

YES

YES

4-2-9 Irregular Density

4-10 Samsung Electronics

Troubleshooting

Is it regular

interval of 94mm?

Obstacles stuck on OPC's
surface

-> Clean the OPC and
machine or replace
developer.

When putting in/out the
developer, scratch is made.

-> Replace the developer.

Transfer

voltage is normal?

D/R in developing unit has
the defect.

-> Replace the developer.

Too high voltage supplied
due to the setting error of
transfer voltage.

-> Adjust/replace HVPS.

NO

NO

YES

YES

4-2-10 White Spot

Recommended
OHP film used?

Inserted over

than 10 films into

the MPF?

When multi-page OHP printng,
less than 10 films are
guranteed. (Reduce the
number of films and re-insert
after Paper check LED is off)

Use the recommended film.

When OHP

printing, does the fan

temporarily stops

and revolves?

Use the recommended film.

Other parts are touching the
fan and prevents it from
revolution.

-> Check and repair.

NO

NO NO

YES

YES

YES

4-2-11 Trembling at the End When OHP Printing

4-11Samsung Electronics

Troubleshooting

After printing

completed, any error

related fuser?

Both ends

of thermostat

open?

Replace thermostat
and re-test.

Replace the contol
component on engine
board.

Check any contact
problem in thermistor
and repair.

The machine

placed under the

severe low tempera-

ture for a long

time?

Place the machine
at normal
temperature and
re-test.

While printing,

the voltage of pin 46

of U5 (CPU) on engine

board is 2.7V

- 3.0V?

Thermistor's

contact is OK?

Open the top

cover. When black

printing, is the fuser NIP

width is 3.0-

3.5mm?

The paper used is too
thick or contains too
much cotton in it.

-> Re-test with the
recommended paper.

Check if the hardness of
P/R, and spring force is OK?
(hardness: 24 degree,
spring's force: 3 Kg)

Re-assemble

thermistor.

NO

NO

NO

NO

NO

NO

YES

YES

YES

YES

YES

YES

4-2-12 Poor Fusing Grade

4-12 Samsung Electronics

Troubleshooting

4-3 Malfunction

Plug in the

power cord?

The power

voltage supplying is

the same as

rating?

The fan

revolves when

powered on?

LEDs blink

once when

powered on?

The On-Line

key is being pressed

or shortage on

the panel

board?

Repair/replace the
board.

Check the voltage first and plug
the power cord.

Supply the power as the rating.

Connections

on board are OK?

Re-connect firmly
and re-test.

The connection
error between
controller board
and panel board
or malfunction
of boards.

-> Replace the
boards.

Fuse of SMPS

is open?

Shortage
between 5V and
GND, or between

24V and

GND?

Replace the fuse.

Toner cartridge

is in the set?

Detect failure due to the
board which detects top
cover open or switch error.

-> Replace the board or switch.

Put in the
cartridge.

Remove the shortage
or replace the board.

NO

NO

NO

NO

NO

NO

NO NO

NO

YES

YES

YES

YES

YES

YES

YES

YES

YES

4-3-1 No Power (LED Off)

4-13Samsung Electronics

Troubleshooting

Less than 10W?

AC is being supplied?

The voltage

of pin #46 of U5

(CPU) on the engine board

is about 3.0V when

printing?

END

Thermostat is open due to the heat etc.

-> Replace the thermostat.

Check the PCI and fusing
control part and CN202
on the engine board.

-> Replace the component
or replace the engine
board.

Measure the resistance
at the both ends of AC
line with covers open.

Remove the covers.

Re-assemble the top
cover and close it.

Thermistor, connecting point or engine
board defected. -> Repair/replace the
component/board.

NO

NO

NO

YES

YES

YES

4-3-2 Fuser Error

4-14 Samsung Electronics

Troubleshooting

Sounds the

solenoid on when starts

print?

Does the

paper move?

Does the

paper move more than

100mm?

The engine board and joint
board defected.

-> Replace boards.

The solenoid defected.

-> Replace it.

The pick-up unit is
assembled wrong.

-> Re-assemble or replace
the unit.

Feeder

sensor and paper

width detect sensor

are assembled

reverse?

Switch them.

The sensor and
joint boards defected.

-> Repair/replace.

Too many

papers in the

feeder?

Paper guides

fit the paper width?

Paper end curled?

Does the

extender pulled out?

<Recommendation>
Use the MPF for the thick
paper such as envelope
and cardstock.

Reduce the amount
and re-test.

Take out the paper
and re-insert.

Use the recommended
and quality paper.

Pull out the
extender.

NO

NO

NO

NO

NO

NO

NO

YES

YES

YES

YES

YES

YES

YES YES

4-3-3 Paper Jam (Mis-feeding)

4-15Samsung Electronics

Troubleshooting

Paper

stopped before

the OPC?

Check the LSU and
if it has the defect.

->Replace it.

Paper

stopped before

the fuser?

Severe skew

when feeding?

Adjust the paper guides to fit the
paper width.

The force of springs pressing the
developer is weak.

-> Check guide-DEVE.

The paper

came out through

between fuser and

developer?

Too thin

or sensitive paper to

static electricity?

Use the recommended
paper.

Check guide transfer
is grounded. Check
the shutter prevents
feeding.

Check the input path
to the fuser (such as
mis-assembly).

The

actuator of

paper exit sensor

works OK?

Check the actuator exists and its
operation and around the engine board.

-> Replace.

Is the paper

rolled around the

presseure

roller?

Remove the fuser, remove
the paper and replace the
pressure roller, if necessary.

Feeds

multiple pages?

Reduce the amount
and retest.

Check the roller
and ribs of fuser
are in place, and
remove burrs, if
any.

-> Remove the
factors of jam.

NO NO NO

NO

NO

NO

NO

NO

YES

YES

YES

YES

YES

YES

YES

YES

4-3-4 Paper Jam (Jam 1)

4-16 Samsung Electronics

Troubleshooting

4-4 DCU Control

4-4-1 DCU Setup

DCU is used to diagnose the printer malfunctions. To use DCU, open and remove the PrinterÕs exit cover in
front, and remove the bottom cover from left. Connect the DCU harness wire (10 pin-to-4 pin) to CN3 (4 pins)
on the control board.

4-4-2 Status Code

Connect the DCU to the printer and turn power on. The DCU display Status Code in the 7 segment LEDs.
There are two kinds of Status Codes; Normal and Error. And their codes mean the printer operating status.

NORMAL STATUS CODE

These codes mean paper location on the paper path when the printer is printing, or warming up.

61 Warm up The printer warms up when the printer is turned on or the cover is closed, or

wake from sleep mode.

00~04 Ready(paper type) The printer is in printable state. The paper type is sensed after

one page printing.

20 Print Start The code is displayed when engine controller is received ÔPRINTÕ command

from the video controller.

30 Feed Sensor On It means that paper is passing the feed sensor.

40 Feed Sensor Off It means that paper passed the feed sensor.

50 Paper out It means that paper passed the exit sensor.

69 Sleep Mode It means that the printer fuser is turned off, and the power consumption is

minimized.

ERROR STATUS CODE

If the printer stops printing by any malfunction, the DCU displays its error status code.

60,62,68 Fuser Error These codes mean the fuser error status. Heat lamp, thermistor, thermostat

open or thermistor short. The ÔLow Temperature ErrorÕ is checked when the
printer is printing.

64 Cover Open The printer cover open or no toner cartridge in the machine.

70 No Paper The paper is not loaded in the printer paper tray.

71 Paper Jam 0 Displays when the paper leading edge stops between the pick-up unit and

the feed sensor.

72 Paper Jam 1 Displays when the paper leading edge stops between the feed sensor and the

exit sensor.

73 Paper Jam 2 Displays when the paper leading edge stops after the exit sensor.

95 LSU Not Ready The LSU scanner motor is not ready or ÔHsyncÕ signal is not output.

4-4-3 Diagnostic Mode

When the printer malfunction occurs and DCU displays Error Status Code, you can use the Diagnostic Mode to
find a problem and fix it.

DIAGNOSTIC CODE

When you fix the malfunction, you can make only a unit of machine operated in Diagnostic mode. To enter
Diagnostic mode, push three buttons ( [DOWN], [SHIFT], [STOP] ) simultaneously and turn the printer power
on. When the DCU displays Ô78Õ, release the keys in 2-3 seconds, then the DCU displays Ô00Õ. By using [UP] or
[SHIFT] and [DOWN] keys, select the desired Diagnostic Code, and push the [ENTER] key to perform the
operation. To stop its operation, push the [SHIFT] and [ENTER] buttons.

00 MAIN MOTOR OPERATING SYSTEM

Only main motor turns continuously.

01 MAIN HIGH VOLTAGE ON

There is output of -1400V to MHV terminal.

02 TRANSFER HIGH VOLTAGE (-) ON

There is output of -800V to THV terminal.

03 THV (+) REFERENCE ON

There is output of +800V to THV terminal.

04 DEV/SUPPLY HIGH VOLTAGE & PTL ON

There are output DEV and SUPPLY high voltage to each HV terminals, the PTL lights. At this
time, the left one of three LEDs (Diagnostic Mode Indicator) in the DCU lights, and DEV HV is ­300V. To change this voltage, push the [UP] button, and two (center and right) of three LEDs light,
there are output -350V to DEV HV terminal.

05 LSU OPERATING SYSTEM

The scanning motor in LSU turns and the right one of three LEDs lights. To check the LD (Laser
Diode) in the LSU at this state, push the [UP] button, the LD is driven, and the center LED lights.
If the LD is normal, all three LEDs light.

06 PICKUP CLUTCH ON

The solenoid in machine operate. To release the solenoid, push the [SHIFT] and [ENTER] buttons.

07 PEMPTY/PWIDTH/NEW CRU SENSOR TEST

When you make the actuator of PEMPTY/PWIDTH sensor operate, the left or right one of three
LEDs lights. If you set new CRU in the machine in this mode, the right LED lights.

08 FEED & EXIT SENSOR TEST

The feed & exit sensor also can be tested by the same method of the code Ô06Õ.

4-17Samsung Electronics

Troubleshooting

4-18 Samsung Electronics

Troubleshooting

09 COVER OPEN SENSOR TEST

Same method of the code Ô06Õ.

10 FUSER TEST

When you push the [ENTER] button, the right LED lights, and the fuser temperature raises to
Ready. If you push the [UP] button, the center LED lights, and it raises to printing temperature.
When you push the [UP] button once more, the left LED lights, and it raises overheating
temperature.

11 HOT BURN TEST

When you push the [ENTER] button in this code, the machine prints endlessly without any
sensing operation. To stop this operation, turn the printer power off.

12 CLEANING MODE PRINT

The machine prints one page to clean the OPC drum in CRU.

13 THV (+) TRIGGER, ALL HV & FAN ON

There are all output of high voltages to each HV terminal, and the LSU/FAN operate.
In this mode, the engine controller senses electric resistance of the transfer roller, and output
transfer high voltage corresponding to it. If there isnÕt CRU in the machine, THV output is +199V
~ +2100V.

14 THV(+) REFERENCE ON

If you push the [ENTER] button in this mode, there is output -800V(±10V) to the THV terminal.

4-4-4 Self Test Button

When you push this button, the machine prints Ôvertical lineÕ pattern while it is pushed.

When you push this button and turn the Printer power on, the DCU displays code Ô89Õ, and the Printer warms
up. After warmed up, it is in ÔReadyÕ state, and code Ô88Õ is displayed in DCU. In this mode, the machine does
all printing operation (demo page printing and printing the data from PC) without all sensor operating. If you
diagnose the control board with malfunction printer engine, this mode is very useful.