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Brother International MFC-9850 Service Manual - Page 86

the temperature of the heat-fixing unit, the system misinterprets the hot heater as being cold.

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• When securing the lock plate R with screw "d," be sure to use the plastic jig as shown below to avoid damaging the edge of the FU lamp with a screwdriver. Lock plate R "d" FU lamp Plastic jig • A new heat-fixing unit will be provided with the heater thermistor harness being taped to the unit. Before installing the unit, remove the tape. • When setting the heat-fixing unit back into place, make sure that the heater wires are routed through the latch of the fan duct (see the illustration given on page IV-41) and then route the long heater wire as shown below. • If you remove and reinstall the heat-fixing unit because of any failure, make the machine enter the maintenance mode (see Note) after completion of reassembly and then make it exit from the mode (by pressing the 9 key twice). Otherwise, the heat-fixing unit may not become energized because of the following reason: If the failure of the heat-fixing unit is caused by an opening of the thermistor circuit (that senses the temperature of the heat-fixing unit), the system misinterprets the hot heater as being cold. As a result, the temperature of the heat-fixing unit may become excessively high. To prevent the system from heating the hot heater further at the next powering-on, it is designed so that the heater will not be energized. To cancel this setting, you need to carry out the above maintenance-mode procedure. (Note) Entry into the maintenance mode Machines w/ fax: Press the Function/Menu, *, 2, 8, 6, and 4 keys. Machines w/o fax: Press the Menu, 0, 2, 8, 6, and 4 keys. IV - 40

Section	Page
DCP1200, MFC9600, MFC9750, MFC9850, MFC9870 Parts and Service Manual.pdf	1
CHAPTER I. GENERAL DESCRIPTION	6
1. MACHINE OUTLINE	7
1.1 External Appearance and Weight	7
1.2 Components	7
2. SPECIFICATIONS	8
CHAPTER II. INSTALLATION	27
1. INSTALLING THE UPDATE DATA TO THE	28
CHAPTER III. THEORY OF OPERATION	31
1. OVERVIEW	32
2. MECHANISMS	33
2.1 Scanner Mechanism	34
2.2 Laser Printing Mechanism	36
2.2.1 Paper pick-up and registration mechanism	36
2.2.2 Print process mechanism	37
2.2.3 Heat-fixing mechanism	39
2.2.4 Paper ejecting mechanism	40
2.3 Sensors and Actuators	41
3. CONTROL ELECTRONICS	43
CHAPTER IV. DISASSEMBLY/REASSEMBLY AND	45
1. DISASSEMBLY/REASSEMBLY	47
Safety Precautions	47
Preparation	48
How to Access the Object Component	48
Disassembly Order Flow	49
1.1 Lower Rear Cover	50
1.2 Access Plates R and F	50
1.3 Paper Cassette	51
1.4 Document Tray ASSY	52
1.5 Upper Rear Cover	54
1.6 ADF Unit	55
1.7 Scanner Unit and Control Panel ASSY	62
1.8 Relay PCB	71
1.9 Speaker	72
1.10 Scanner Mount	73
1.11 Paper Sub Tray and Tray Holder	76
1.12 VC Cover, VC Bracket, and VC Connector PCB (for models supporting	77
1.13 Front Cover	78
1.14 Outer Chute and Paper Pinch Rollers	79
1.15 Main Cover	80
1.16 Switch Cover (for models not equipped with a power switch)	81
1.17 Laser Unit	82
1.18 Heat-fixing Unit and FU Lamp	83
1.19 Fan	87
1.20 Drive Gear ASSY and Main Motor ASSY	89
1.21 NCU Shield and NCU PCB*	91
1.22 Bottom Plate, Main PCB, and Bottom Insulation Film	93
1.23 Low-voltage Power Supply PCB and Power Inlet	97
1.24 Inner Insulation Film, High-voltage Power Supply PCB, Engine PCB,	99
1.25 Toner Sensor (light-receiver) PCB and Toner Sensor (LED) PCB	101
1.26 Gears and Paper Pick-up Roller	102
1.27 Paper Feed Roller ASSY	103
1.28 Clutch Levers, Cassette Guide L, and Solenoid	104
1.29 Cleaning of High-voltage Contacts and Grounding Contacts	105
2. LUBRICATION	107
[ 1 ] ADF unit	107
[ 2 ] Scanner mount	108
[ 3 ] Drive gear ASSY	109
[ 4 ] Paper cassette	110
CHAPTER V. MAINTENANCE MODE	112
1. ENTRY INTO THE MAINTENANCE MODE	113
2. LIST OF MAINTENANCE-MODE FUNCTIONS	114
3. DETAILED DESCRIPTION OF	116
3.1 EEPROM Parameter Initialization	116
3.2 Printout of Scanning Compensation Data	117
3.3 ADF Performance Test	119
3.4 Test Pattern 1	120
3.5 Firmware Switch Setting and Printout	121
[ A ] Firmware switch setting	121
[ B ] Printout of firmware switch data	165
3.6 Operational Check of LCD	166
3.7 Operational Check of Control Panel PCB	166
3.8 Sensor Operational Check	168
3.9 CCD Scanner Area Setting	169
3.10 EEPROM Customizing	169
3.11 Erasure of Received FAX Messages Temporarily Stored in the Flash Memory (Not applicable	170
3.12 Machine Error Code Indication	170
3.13 Output of Transmission Log to the Telephone Line (Not applicable to machines w/o fax)	171
3.14 Cancellation of the Memory Security Mode (Not applicable to the American versions and	171
CHAPTER VI. ERROR INDICATION AND TROUBLESHOOTING	173
1. ERROR INDICATION	174
1.1 Machine Errors	174
[ 1 ] Error messages on the LCD	174
[ 2 ] Error codes shown in the \	177
1.2 Communications Errors (Not applicable to machines w/o fax)	179
2. TROUBLESHOOTING	189
2.1 Introduction	189
2.2 Precautions	189
2.3 Checking prior to Troubleshooting	189
2.4 Troubleshooting Procedures	191
[ 1 ] Control panel related	191
[ 2 ] Telephone related	191
[ 3 ] Communications related	192
[ 4 ] Paper/document feeding related	192
[ 5 ] Print-image related	193
[ 6 ] PC-driven or video capture-driven printing	199
Location of High-voltage Contacts and Grounding Contacts	200
Appendix 1. EEPROM Customizing Codes	202
Appendix 2. Circuit Diagrams	205
A. Main PCB	206
B. Engine PCB	213
C. NCU PCB	214
D. Control Panel PCB	218
E. Relay PCB	221
F. Power Supply PCB	222
pl_mfc9750_9850_9870.pdf	226
List1(MAIN FRAME)	229
List2(LASER UNIT)	231
List3(PAPER TRANSPORT)	233
List4(PAPER CASSETTE)	235
List5(HEAT FIXING UNIT)	237
List6(COVER)	239
List7(SCANNER UNIT)	241
List8(ADF&TRAY)	243
List9(CONTROL PANEL MFC9750)	245
List9(C PANEL MFC9850 9870)	247
List10(PCB ASSY)	249
List11(ACCESSORIES)	251
List12(PRINTED MATERIAL)	253
List13(CARTON)	255
DCP1200pc.pdf	257
List1(MAIN FRAME)	260
List2(LASER UNIT)	262
List3(PAPER TRANSPORT)	264
List4(PAPER CASSETTE)	266
List5(HEAT FIXING UNIT)	268
List6(COVER)	270
List7(SCANNER UNIT)	272
List8(ADF&TRAY)	274
List9(CONTROL PANEL DCP1200)	276
List9(CONTROL PANEL MFC9600)	278
List10(PCB ASSY)	280
List11(ACCESSORIES)	282
List12(PRINTED MATERIAL)	284

Match case Limit results 1 per page

- 40

•

When securing the lock plate R with screw "d," be sure to use the plastic jig as shown below to

avoid damaging the edge of the FU lamp with a screwdriver.

•

A new heat-fixing unit will be provided with the heater thermistor harness being taped to the

unit.

Before installing the unit, remove the tape.

•

When setting the heat-fixing unit back into place, make sure that the heater wires are routed

through the latch of the fan duct (see the illustration given on page IV-41) and then route the

long heater wire as shown below.

•

If you remove and reinstall the heat-fixing unit because of any failure, make the machine enter

the maintenance mode (see Note) after completion of reassembly and then make it exit from

the mode (by pressing the

key twice).

Otherwise, the heat-fixing unit may not become

energized because of the following reason:

If the failure of the heat-fixing unit is caused by an opening of the thermistor circuit (that senses

the temperature of the heat-fixing unit), the system misinterprets the hot heater as being cold.

As a result, the temperature of the heat-fixing unit may become excessively high.

To prevent

the system from heating the hot heater further at the next powering-on, it is designed so that

the heater will not be energized.

To cancel this setting, you need to carry out the above

maintenance-mode procedure.

(Note)

Entry into the maintenance mode

Machines w/ fax:

Press the

Function/Menu

, and

keys.

Machines w/o fax:

Press the

, and

keys.

"d"

Plastic jig

FU lamp

Lock plate R