Samsung ML-4500 Service Manual E.09

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	2,500 Pages
Pickup Roller	60,000 Pages
Feed Roller	60,000 Pages
Transfer Roller	60,000 Pages
Fuser	60,000 Pages
Driver	60,000 Pages

4-2 Print Quality

	No	Roller	Abnormal image period	Kind of abnormal image
	1	OPC Drum	75.4mm	•White spot on black image
				•Black spot
	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

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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.

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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.

00MAIN MOTOR OPERATING SYSTEM Only main motor turns continuously.

01MAIN HIGH VOLTAGE ON (THV)

There is output of -1550V to MHV terminal.

02TRANSFER HIGH VOLTAGE (-) ON (THV - ) There is output of -1300V to THV terminal.

03TRANSFER HIGH VOLTAGE (+) REFERENCE ON (THV + ) There is output of +1300V to THV terminal.

04DEV/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.

05LSU 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.

06PICKUP CLUTCH ON

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

07PEMPTY/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.

08FEED & EXIT SENSOR TEST

The feed & exit sensor also can be tested by the same method of the code ‘06’.

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Troubleshooting

09COVER OPEN SENSOR TEST Same method of the code ‘06’.

10FUSER 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.

11HOT 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.

12CLEANING MODE PRINT MODE

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

13THV (+) 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.

14PTL TEST

This operation mean PTL LED status.

15FAN 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.

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Troubleshooting

4-4 Troubleshooting Flow Chart

Vertical black line and band

OK after replacing developer?

NO

OK after replacing the LSU?

YES

Any obstacles ON mirror lens of LSU and laser path?

	YES	Any obstacles on	NO
		the developer blocking		Replace the developer
		the laser beam.
		YES

OK after

NO

removing the obstacles?

YES

END

NO		Remove part on the paper
		path causing the trouble

NO

Replace the LSU

YES

Remove the obstacles.

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Troubleshooting

No Image

No image?

YES

Self test pattern prints?

YES

Check connection to computer or replace controller

NO	A on
	next page

NO	Self testing		NO		Re-test after replacing the
	is possible via				conector or Main board
	Tech Mode?
		YES

Take out the cartridge and prepare the tester for electronic connection

Is the OPC

terminal of machine NO is well-connected

to Frame?

YES

Does the

video data line to NO LSU transit to High/Low

when printing?

YES

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

Repair or replace the GND terminal

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

or board

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A

Is the connection of

OPC GND and Frame Ground correct? (less than

10 ‰ )

	YES
		NO
Trnasfer High
voltage OK? (on the
transfer roller
shaft)
	YES

Troubleshooting

Check the connection of frame Ground and OPC GND

Are the

connection terminal NO Repair or replace terminal and connection

correct?

YES

Replace HVPS or repair defective component

Developing			NO			NO
(-350V) and supplying				Is the connection				Repair or replace terminal
(-550V) voltage				terminal OK?
are OK?
YES					YES
			Replace HVPS or repair defective component

Does the					Transfer roller might be out of its location
					-> Locate the roller into its place
counter indicate over			NO
the toner’s guarranty					This could occurrs when he power of LSU is low or
life					the density is low due to the obstacles on the window
	YES				-> Replace LSU or clean the window
Replace the toner cartridge

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Troubleshooting

Light image

Is it not over

NO

the guaranty life of dot

Replace the developer

counter?

YES

Is the toner save

YES

Ok after setting to the

YES

END

mode or the light mode

normal mode?

is selected?

NO

NO

Is the high voltage

NO

Replace the HVPS

normal? (charging,

developing,

transfer)

YES

YES

NO

YES

HVPS works OK?

Any obstacles on the	YES	Remove the obstacles
gab between high voltage
terminal and
developer?
NO
Transfer roller	NO	Clean transfer roller
works OK?		and gear holder
YES
OK after replacing	YES	Replace the LSU
LSU?

NO

Replace the developer

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All Black

All black in printing area?

YES

Is transfer voltage supplied (-1.55 KV)?

YES

Is the

Hsync/ signal received in LSU?

YES

Troubleshooting

	Does the				Check the path among video
NO					controller, engine board,
	video data line to LSU		NO
					HVPS, LSU for the shortage
	transit to High/Low when
					or open -> Repair or replace
	printing?
					the boards
		YES

Replace LSU

NO

Repair or replace HVPS

NO

Replace LSU

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

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