Samsung ML-4500 Service Manual E.09

Samsung Electronics 4-1

4. Maintenance & Troubleshooting

4-1 Preventative Maintenance

The cycle period outlined below is a general guideline for maintenance. The example list is for an average usage of 50 transmitted and received documents per day. Environmental conditions and actual use will vary these factors. The cycle period given below is for reference only.

COMPONENT REPLACEMENT CYCLE

Cartridge Pickup Roller Feed Roller Transfer Roller Fuser Driver

2,500 Pages 60,000 Pages 60,000 Pages 60,000 Pages 60,000 Pages 60,000 Pages

4-2 Print Quality

No Roller Abnormal image period Kind of abnormal image

1 OPC Drum 75.4mm

2 Charge Roller 37.7mm Black spot

3 Supply Roller 26.8mm Horizontal density band

4 Develope Roller 31.6mm Horizontal density band

5 Transfer Roller 47.1mm Black side contamination/transfer fault

6 Heat Roller 57.1mm Black spot, White spot

7 Pressure Roller 56.5mm Black side contamination

•White spot on black image

•Black spot

4-2 Samsung Electronics

Troubleshooting

4-3 DCU Control

4-3-1 DCU Setup

DCU is used to diagnose the printer malfunctions. To use DCU, open and remove the Printer’s exit cover in front, and remove the bottom cover from left. Connect the DCU harness wire (10 pin-to-4 pin) to CN9 (4 pins) on the control board.

4-3-2 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.

00~05 Ready(paper type) The printer is in printable state. The paper type is sensed after

one page printing. 00: Legal , 01: Letter , 02: A4 , 03: EXEC , 04: B5 , 05: Folio

20 Print Start The code is displayed when engine controller is received ‘PRINT’ 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 ‘Low Temperature Error’ is checked when the

printer is printing.

60: Open Fuser Error

62: Low Heat Error

68: Over Heat Error 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 ‘Hsync’ signal is not output.

Samsung Electronics 4-3

Troubleshooting

4-3-3 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 ‘78’, release the keys in 2-3 seconds, then the DCU displays ‘00’. 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 (THV)

There is output of -1550V to MHV terminal.

02 TRANSFER HIGH VOLTAGE (-) ON (THV - )

There is output of -1300V to THV terminal.

03 TRANSFER HIGH VOLTAGE (+) REFERENCE ON (THV + )

There is output of +1300V to THV terminal.

04 DEV/SUPPLY HIGH VOLTAGE

There is output DEV and SUPPLY high voltage to each HV terminals. At this time, the left one of three LEDs (Diagnostic Mode Indicator) in the DCU lights, and DEV HV is -630V. To change this voltage, push the [UP] button, and two (center and right) of three LEDs light, there are output

-530V 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 ‘06’.

4-4 Samsung Electronics

Troubleshooting

09 COVER OPEN SENSOR TEST

Same method of the code ‘06’.

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 MODE

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

13 THV (+) TRIGGER, ALL HV

There is 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 isn’t CRU in the machine, THV output is +199V ~ +2100V.

14 PTL TEST

This operation mean PTL LED status.

15 FAN TEST

This operation mean FAN status.

4-3-4 Self Test Button

When you push this button, the machine prints ‘vertical line’ pattern while it is pushed. When you push this button and turn the Printer power on, the DCU displays code ‘89’, and the Printer warms

up. After warmed up, it is in ‘Ready’ state, and code ‘88’ 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.

Samsung Electronics 4-5

Troubleshooting

Vertical black line and band

YES

OK after

replacing the LSU?

Remove part on the paper path causing the trouble

OK after replacing

developer?

Any obstacles on

the developer blocking

the laser beam.

OK after

removing the

obstacles?

Any obstacles ON

mirror lens of LSU and

laser path?

Remove the obstacles.

Replace the LSU

Replace the developer

END

YES

4-4 Troubleshooting Flow Chart

4-6 Samsung Electronics

Troubleshooting

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 deffective matters in the machine

Self test

pattern prints?

No image?

Self testing

is possible via

Tech Mode?

Is the OPC

terminal of machine

is well-connected

to Frame?

Does the

video data line to

LSU transit to High/Low

when printing?

Re-test after replacing the conector or Main board

A on

YES

No Image

Samsung Electronics 4-7

Troubleshooting

Transfer roller might be out of its location

-> Locate the roller into its place This could occurrs when he power of LSU is low or

the density is low due to the obstacles on the window

-> Replace LSU or clean the window

Trnasfer High

voltage OK? (on the

transfer roller

shaft)

Is the

connection of

OPC GND and Frame Ground

correct? (less than

10 ‰)

Are the

connection terminal

and connection

correct?

Repair or replace terminal

Replace HVPS or repair defective component

Is the connection

terminal OK?

Check the connection of

frame Ground and OPC GND

Replace HVPS or repair defective component

Repair or replace terminal

Developing

(-350V) and supplying

(-550V) voltage

are OK?

Does the

counter indicate over

the toner’s guarranty

life

Replace the toner cartridge

YES

4-8 Samsung Electronics

Troubleshooting

Replace the developer

YES

END

YESYES

YES

Replace the HVPS

Ok after setting to the

normal mode?

YES

Remove the obstacles

YES

Clean transfer roller and gear holder

YES

Replace the LSU

Replace the developer

Is it not over

the guaranty life of dot

counter?

Is the toner save

mode or the light mode

is selected?

Is the high voltage

normal? (charging,

developing,

transfer)

Any obstacles on the

gab between high voltage

terminal and

developer?

Transfer roller

works OK?

OK after replacing

LSU?

HVPS works OK?

Light image

Samsung Electronics 4-9

Troubleshooting

All black in

printing area?

Is transfer

voltage supplied

(-1.55 KV)?

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

YES

All Black

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