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Brother International MFC 8500 Service Manual - Page 32

(1) Charging process, When the laser-sensitive drum holds a positive electrical charge

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(1) Charging process The high-voltage power supply applies DC bias to the corona wire to generate ion on the grid. The ion uniformly charges the surface of the laser-sensitive drum to approx. 870V which is kept by the voltage regulator grounding the grid to the frame. (2) Exposing process When the laser-sensitive drum holds a positive electrical charge, the laser beam issued from the laser unit scans the drum according to the print image to expose the drum surface for neutralizing the spots where black should be, forming an electrostatic latent image. III - 6

Section	Page
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	21
1. INSTALLING THE UPDATE DATA TO THE FACSIMILE MACHINE	22
2. SETTING ID CODES TO FACSIMILE MACHINES	24
CHAPTER III. THEORY OF OPERATION	26
1. OVERVIEW	27
2. MECHANISMS	28
2.1 Scanner Mechanism	29
2.1.1 Document feeding and ejecting mechanism	29
2.1.2 Scanner	29
2.2 Laser Printing Mechanism	30
2.2.1 Paper pick-up and registration mechanism	30
2.2.2 Print process mechanism	31
(1) Charging process	32
(2) Exposing process	32
(3) Developing process	33
(4) Transferring process	33
2.2.3 Heat-fixing mechanism	34
2.2.4 Paper ejecting mechanism	35
2.3 Sensors and Actuators	36
3. CONTROL ELECTRONICS	38
CHAPTER IV. DISASSEMBLY/REASSEMBLY AND LUBRICATION	40
1. DISASSEMBLY/REASSEMBLY	42
Safety Precautions	42
Preparation	43
How to Access the Object Component	43
Disassembly Order Flow	44
1.1 Rear Cover	45
1.2 Access Plates R and F	45
1.3 Control Panel ASSY	46
1.4 Panel Rear Cover and Control Panel	47
1.5 Document Feed Roller ASSY, Document Ejection Roller ASSY, and Pinch Rollers	50
1.6 CIS Unit	51
1.7 Scanner Frame ASSY (Scanner Motor, Scanner Drive Unit, Document Take-in Roller,	52
1.8 Top Cover (Exit Roller, Speaker, and Document Guides)	56
1.9 Handset Mount and Hook Switch PCB (for models equipped with a handset)	62
1.10 Paper Sub Tray	64
1.11 VC Cover, VC Bracket, and VC Connector PCB (for models supporting video capture)	65
1.12 Front Cover	66
1.13 Outer Chute and Paper Pinch Rollers	67
1.14 Main Cover	68
1.15 Switch Cover	69
1.16 Laser Unit	70
1.17 Heat-fixing Unit and FU Lamp	71
[Disassembling the heat-fixing unit]	73
1.18 Fan	85
1.19 Drive Gear ASSY and Main Motor ASSY	87
1.20 NCU Shield and NCU PCB	89
1.21 Bottom Plate, Main PCB, and Bottom Insulation Film	91
1.22 Low-voltage Power Supply PCB and Power Inlet	95
1.23 Inner Insulation Film, High-voltage Power Supply PCB, Engine PCB, and 2nd Cassette Relay PCB*	97
1.24 Toner Sensor (light-receiver) PCB and Toner Sensor (LED) PCB	99
1.25 Gears and Paper Pick-up Roller	100
1.26 Paper Feed Roller ASSY	101
1.27 Clutch Levers, Cassette Guide L, and Solenoid	102
1.28 Paper Cassette	103
1.29 Cleaning of High-voltage Contacts and Grounding Contacts	104
2. LUBRICATION	106
[ 1 ] Document feed roller ASSY and document ejection roller ASSY	106
[ 2 ] Control panel locks	107
[ 3 ] Scanner frame ASSY, document take-in roller and its shaft, and separation roller and its shaft	107
[ 4 ] Top cover	108
[ 5 ] Drive gear ASSY	109
[ 6 ] 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 MAINTENANCE-MODE FUNCTIONS	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	123
3.6 Operational Check of LCD	124
3.7 Operational Check of Control Panel PCB	124
3.8 Receiver Volume Adjustment (applicable to the American version only)	126
3.9 Sensor Operational Check	127
3.10 Fine Adjustment of Scanning Start/End Position	128
3.11 CIS Scanner Area Setting	129
3.12 EEPROM Customizing	129
3.13 Display of the Equipment's Log Information	130
3.14 Equipment Error Code Indication	131
3.15 Output of Transmission Log to the Telephone Line	131
3.16 Cancellation of the Memory Security Mode (applicable to the European version only)	132
CHAPTER VI. ERROR INDICATION AND TROUBLESHOOTING	134
1. ERROR INDICATION	135
1.1 Equipment Errors	135
[ 1 ] Error messages on the LCD	135
[ 2 ] Error codes shown in the \	139
1.2 Communications Errors	141
2. TROUBLESHOOTING	151
2.1 Introduction	151
2.2 Precautions	151
2.3 Checking prior to Troubleshooting	151
2.4 Troubleshooting Procedures	153
[ 1 ] Control panel related	153
[ 2 ] Telephone related	153
[ 3 ] Communications related	154
[ 4 ] Paper/document feeding related	154
[ 5 ] Print-image related	155
Location of High-voltage Contacts and Grounding Contacts	162
Appendix 1. EEPROM Customizing Codes	164
Appendix 2. Firmware Switches (WSW)	167
Appendix 3. Circuit Diagrams	215
A. Main PCB (MFC8500)	216
B. Main PCB (MFC9660)	226
C. Engine PCB	227
D. NCU PCB	228
E. Control Panel PCB	232