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Brother International 1920CN Service Manual - Page 41

Sensors and Actuators, Document sensor PCB

UPC - 012502607137

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2.3 Sensors and Actuators This machine has ten sensors: eight photosensors and two thermistors as described below. Sensor name Document front sensor Document rear sensor Manual insertion sensor Registration sensor Cassette sensor Paper ejection sensor Toner sensor Type Photosensor Photosensor Photosensor Photosensor Photosensor Photosensor Photosensor Cover sensor Heater thermistor In-casing temperature sensor Photosensor Thermistor Thermistor Located on Document sensor PCB Document sensor PCB Engine PCB Engine PCB Engine PCB Paper ejection sensor PCB Toner sensor (LED) PCB and toner sensor (light-receiver) PCB Toner sensor (LED) PCB Heat-fixing unit Left-hand plate of the main chassis • Document front sensor which detects the presence of documents. • Document rear sensor which detects the leading and trailing edges of pages to tell the control circuitry when the leading edge of a new page has reached the starting position and when the scan for that page is over. • Manual insertion sensor which detects whether paper is inserted manually through the paper slot or whether paper fed through the paper cassette has jammed. • Registration sensor which detects the leading and trailing edges of recording paper, which allows the controller to determine the registration timing and check paper jam. • Cassette sensor which detects whether the paper cassette is loaded. • Paper ejection sensor which detects whether the recording paper goes out of the machine. • Toner sensor which detects whether there is toner or a toner cartridge is loaded. • Cover sensor which detects whether the front cover is closed. • Heater thermistor which allows the controller to monitor the temperature of the heater roller of the fixing unit. • In-casing temperature sensor which allows the controller to monitor the temperature inside the machine. The above photosensors are a photointerrupter consisting of a light-emitting diode and a light-sensitive transistor. Each of them has an actuator separately arranged as shown on the next page. III - 10

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

III

- 10

2.3

Sensors and Actuators

This machine has ten sensors: eight photosensors and two thermistors as described below.

Sensor name

Type

Located on

Document front sensor

Photosensor

Document sensor PCB

Document rear sensor

Photosensor

Document sensor PCB

Manual insertion sensor

Photosensor

Engine PCB

Registration sensor

Photosensor

Engine PCB

Cassette sensor

Photosensor

Engine PCB

Paper ejection sensor

Photosensor

Paper ejection sensor PCB

Toner sensor

Photosensor

Toner sensor (LED) PCB and toner

sensor (light-receiver) PCB

Cover sensor

Photosensor

Toner sensor (LED) PCB

Heater thermistor

Thermistor

Heat-fixing unit

In-casing temperature sensor

Thermistor

Left-hand plate of the main chassis

•

Document front sensor which detects the presence of documents.

•

Document rear sensor which detects the leading and trailing edges of pages to tell the control

circuitry when the leading edge of a new page has reached the starting position and when the

scan for that page is over.

•

Manual insertion sensor which detects whether paper is inserted manually through the paper

slot or whether paper fed through the paper cassette has jammed.

•

Registration sensor which detects the leading and trailing edges of recording paper, which

allows the controller to determine the registration timing and check paper jam.

•

Cassette sensor which detects whether the paper cassette is loaded.

•

Paper ejection sensor which detects whether the recording paper goes out of the machine.

•

Toner sensor which detects whether there is toner or a toner cartridge is loaded.

•

Cover sensor which detects whether the front cover is closed.

•

Heater thermistor which allows the controller to monitor the temperature of the heater roller of

the fixing unit.

•

In-casing temperature sensor which allows the controller to monitor the temperature inside the

machine.

The above photosensors are a photo-

interrupter consisting of a light-emitting

diode and a light-sensitive transistor.

Each

of them has an actuator separately arranged

as shown on the next page.