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Brother International IntelliFax-4750 Service Manual - Page 39

Sensors and Actuators, Document sensor PCB

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2.3 Sensors and Actuators This equipment has eleven sensors: eight photosensors, two thermistors and a mechanical switch 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 Hook switch* Photosensor Thermistor Thermistor Mechanical switch Located on Control panel PCB Document sensor PCB Control panel PCB ASSY 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 Hook switch PCB* *For models equipped with a handset • 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 equipment. • 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 equipment. • Hook switch* which detects whether the handset is placed on the handset mount*. 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
FAX4750, FAX5750, FAX8350P, FAX8750P, MFC8300, MFC8600, MFC8700, MFC9650 Parts and Service Manual.pdf	1
CHAPTER I. GENERAL DESCRIPTION	6
1. EQUIPMENT OUTLINE	7
1.1 External Appearance and Weight	7
1.2 Components	7
2. SPECIFICATIONS	8
CHAPTER II. INSTALLATION	25
1. INSTALLING THE UPDATE DATA TO THE	26
CHAPTER III. THEORY OF OPERATION	29
1. OVERVIEW	30
2. MECHANISMS	31
2.1 Scanner Mechanism	32
2.1.1 Document feeding and ejecting mechanism	32
2.1.2 Scanner	32
2.2 Laser Printing Mechanism	33
2.2.1 Paper pick-up and registration mechanism	33
2.2.2 Print process mechanism	34
(1) Charging process	35
(2) Exposing process	35
(3) Developing process	36
(4) Transferring process	36
2.2.3 Heat-fixing mechanism	37
2.2.4 Paper ejecting mechanism	38
2.3 Sensors and Actuators	39
3. CONTROL ELECTRONICS	41
3.1 Configuration	41
3.2 Main PCB	42
3.3 Engine PCB	44
3.4 NCU PCB	45
3.5 Control Panel PCB	48
3.6 Power Supply PCB	49
[ 1 ] Low-voltage power supply PCB	49
[ 2 ] High-voltage power supply PCB	50
CHAPTER IV. DISASSEMBLY/REASSEMBLY AND	52
1. DISASSEMBLY/REASSEMBLY	54
Safety Precautions	54
Preparation	55
How to Access the Object Component	55
Disassembly Order Flow	56
1.1 Rear Cover	57
1.2 Access Plates R and F	57
1.3 Control Panel ASSY	58
1.4 Panel Rear Cover and Control Panel	59
1.5 Document Feed Roller ASSY, Document Ejection Roller ASSY, and Pinch Rollers	62
1.6 CIS Unit	63
1.7 Scanner Frame ASSY (Scanner Motor, Scanner Drive Unit, Document Take-in Roller,	64
1.8 Top Cover (Exit Roller, Speaker, and Document Guides)	68
1.9 Handset Mount and Hook Switch PCB (for models equipped with a handset)	74
1.10 Paper Sub Tray	76
1.11 VC Cover, VC Bracket, and VC Connector PCB (for models supporting video capture)	77
1.12 Front Cover	78
1.13 Outer Chute and Paper Pinch Rollers	79
1.14 Main Cover	80
1.15 Switch Cover	81
1.16 Laser Unit	82
1.17 Heat-fixing Unit and FU Lamp	83
1.18 Fan	87
1.19 Drive Gear ASSY and Main Motor ASSY	89
1.20 NCU Shield and NCU PCB	91
1.21 Bottom Plate, Main PCB, and Bottom Insulation Film	93
1.22 Low-voltage Power Supply PCB and Power Inlet	97
1.23 Inner Insulation Film, High-voltage Power Supply PCB, Engine PCB, and 2nd Cassette Relay	99
1.24 Toner Sensor (light-receiver) PCB and Toner Sensor (LED) PCB	101
1.25 Gears and Paper Pick-up Roller	102
1.26 Paper Feed Roller ASSY	103
1.27 Clutch Levers, Cassette Guide L, and Solenoid	104
1.28 Paper Cassette	105
1.29 Cleaning of High-voltage Contacts and Grounding Contacts	106
2. LUBRICATION	108
[ 1 ] Document feed roller ASSY and document ejection roller ASSY	108
[ 2 ] Control panel locks	109
[ 3 ] Scanner frame ASSY, document take-in roller and its shaft, and separation roller and	109
[ 4 ] Top cover	110
[ 5 ] Drive gear ASSY	111
[ 6 ] Paper cassette	112
CHAPTER V. MAINTENANCE MODE	114
1. ENTRY INTO THE MAINTENANCE MODE	115
2. LIST OF MAINTENANCE-MODE FUNCTIONS	116
3. DETAILED DESCRIPTION OF MAINTENANCE-MODE FUNCTIONS	118
3.1 EEPROM Parameter Initialization	118
3.2 Printout of Scanning Compensation Data	119
3.3 ADF Performance Test	121
3.4 Test Pattern 1	122
3.5 Firmware Switch Setting and Printout	123
3.6 Operational Check of LCD	169
3.7 Operational Check of Control Panel PCB	169
3.8 Receiver Volume Adjustment (applicable to the American version only)	171
3.9 Sensor Operational Check	172
3.10 CIS Scanner Area Setting	173
3.11 EEPROM Customizing	173
3.12 Erasure of Received FAX Messages Temporarily Stored in the Flash Memory (not applicable to	174
3.13 Equipment Error Code Indication	174
3.14 Output of Transmission Log to the Telephone Line	175
3.15 Cancellation of the Memory Security Mode (applicable to the European version only)	175
CHAPTER VI. ERROR INDICATION AND TROUBLESHOOTING	177
1. ERROR INDICATION	178
1.1 Equipment Errors	178
[ 1 ] Error messages on the LCD	178
[ 2 ] Error codes shown in the \	181
1.2 Communications Errors	183
2. TROUBLESHOOTING	193
2.1 Introduction	193
2.2 Precautions	193
2.3 Checking prior to Troubleshooting	193
2.4 Troubleshooting Procedures	195
[ 1 ] Control panel related	195
[ 2 ] Telephone related	195
[ 3 ] Communications related	196
[ 4 ] Paper/document feeding related	196
[ 5 ] Print-image related	197
Location of High-voltage Contacts and Grounding Contacts	204
Appendix 1. EEPROM Customizing Codes	206
Appendix 2. Circuit Diagrams	209
A. Main PCB (FAX4750/MFC8300/MFC8600/MFC8700/FAX8350P/MFC9650)	210
A. Main PCB (FAX5750/FAX8750P)	217
B. Modem PCB	224
C. Engine PCB	227
D. NCU PCB	229
E. Control Panel PCB	234
F. Power Supply PCB	236
pl_fax8350_8750_mfc9650.pdf	241
List1(MAIN FRAME)	244
List2(DOCUMENT SCANNER)	246
List3(LASER UNIT)	248
List4(PAPER TRANSPORT)	250
List5(PAPER TRAY)	252
List6(HEAT FIXING UNIT)	254
List7(COVER)	256
List8(CONTROL PANEL)	258
List9(PCB ASSY)	260
List10(ACCESSORIES)	262
List11(PRINTED MATERIAL)	264
List12(CARTON)	266
FAX4750pc.pdf	268
List1(MAIN FRAME)	271
List2(DOCUMENT SCANNER)	273
List3(LASER UNIT)	275
List4(PAPER TRANSPORT)	277
List5(PAPER CASSETTE)	279
List6(HEAT FIXING UNIT)	281
List7(COVER)	283
List8(CONTROL PANEL)	285
List9(PCB ASSY)	287
List10(ACCESSORIES)	289
List11(PRINTED MATERIAL)	291

Match case Limit results 1 per page

III

- 10

2.3

Sensors and Actuators

This equipment has eleven sensors: eight photosensors, two thermistors and a mechanical switch

as described below.

Sensor name

Type

Located on

Document front sensor

Photosensor

Control panel 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

Hook switch*

Mechanical switch

Hook switch PCB*

*For models equipped with a handset

•

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 equipment.

•

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

equipment.

•

Hook switch* which detects whether the handset is placed on the handset mount*.

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.

Control panel

PCB ASSY