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MFC-7420R
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8-21 Confidential

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Service manual p.1
Models mfc7420 7820n dcp7010 7020 7025 p.1
Allfb service manual p.1
Facsimile equipment p.1
Preface p.3
How this manual is organized p.3
Table of contents p.5
Warning p.11
To use the mfc safely p.11
Safety precautions p.11
Warning p.12
Caution p.12
Choosing a location p.13
This chapter contains external views and names of components and describes their functions information about the keys on the control panel is included to help you check operation or make adjustments p.15
Contents p.15
Chapter 1 parts names functions p.15
1 confidential p.16
Rear view rear view p.16
Front view p.16
Equipment outline p.16
Control panel p.17
Mfc 7420 and mfc 7820n have similar control keys p.17
5 4 3 2 1 p.17
2 confidential p.17
The equipment consists of the following major components p.19
Components p.19
4 confidential p.19
This chapter lists the specifications of each model which enables you to make a comparison of different models p.21
Contents p.21
Chapter 2 specifications p.21
General p.22
4 confidential p.25
When using pcl emulation the edges of the paper that cannot be printed on are shown below p.25
Printable area p.25
Portrait p.25
Note logical page shows the printable area for a pcl driver printable area shows mechanical printable area of the machine therefore the machine can only print within the shaded area when you use a pcl driver p.25
The table below shows the printable areas when printing on portrait for each paper size p.26
Note the paper sizes indicated here should confirm to the nominal dimensions specified by jis except b5 iso b6 iso the dot size is based on 300 dpi resolution p.26
5 confidential p.26
Note logical page shows the printable area for a pcl driver printable area shows mechanical printable area of the machine therefore the machine can only print within the shaded area when you use a pcl driver p.27
Landscape p.27
6 confidential p.27
The table below shows the printable areas when printing on landscape for each paper size p.28
Note the paper sizes indicated here should confirm to the nominal dimensions specified by jis except b5 iso b6 iso the dot size is based on 300 dpi resolution p.28
7 confidential p.28
Specifications list p.29
Mfc7420 7820n p.29
8 confidential p.29
9 confidential p.30
10 confidential p.31
11 confidential p.32
12 confidential p.33
13 confidential p.34
14 confidential p.35
15 confidential p.36
16 confidential p.37
Dcp7010 7020 7025 p.37
17 confidential p.38
18 confidential p.39
19 confidential p.40
20 confidential p.41
21 confidential p.42
22 confidential p.43
Chapter 3 theory of operation p.45
This chapter gives an overview of the scanning and printing mechanisms as well as the sensors actuators and control electronics it aids in understanding the basic principles of operation as well as locating defects for troubleshooting p.45
Contents p.45
Overview p.46
Control section p.46
Confidential 3 1 p.46
Mechanical components p.47
Confidential 3 2 p.47
This mechanism consists of the document cover the scanner unit scanner cover and the automatic document feeder adf the scanner unit consists of a scanner top cover cis unit cis drive assembly and scanner base the detailed illustration on the next page shows the components making up the adf document pull in roller document separation roller document feed roller adf motor and document front and rear sensors for further details on the sensors see section 3 p.48
Scanner mechanism p.48
Confidential 3 3 p.48
This scanner mechanism supports a dual scanning system adf scanning and flat bed scanning they automatically switch to the former at the start of a scan operation if the document front sensor inside the adf detects a document p.49
The feed roller picks up a few sheets or one sheet of paper from the paper tray every time it is rotated and feeds it to the separation roller p.51
Printing mechanism p.51
Paper supply p.51
Confidential 3 6 p.51
4 when the paper is fed the p r solenoid assy is activated first p.52
1 the paper is gripped between the separation roller and separation pad and separated into individual sheets the separation roller is connected to the gear 52 p r p.52
The paper drawn out of the paper tray pushes against the regist front actuator and the paper top position or absence of paper is detected by the actuator movement the tail edge actuator detects the end of the paper fed p.52
Confidential 3 7 p.52
6 the main motor drive is transmitted to the gear 52 p r and the separation roller is turned p.52
5 then the gear 52 p r is pulled by the spring extension p r so that the gears are engaged p.52
3 therefore the main motor drive is not transmitted to the gear 52 p r p.52
2 the section of the gear 52 p r where there is no cog is normally fixed at the position as shown in the figure below by the p r solenoid assy p.52
The regist rear actuator in the path from the feed roller to the transfer roller controls the first print position on the paper the printer starts transferring an image when a definite time passes after the paper is passed through the regist rear actuator p.55
Paper registration p.55
Confidential 3 1 0 p.55
After the paper top position is detected by the regist front actuator the paper separated into individual sheets by the separation roller is fed further for a specified time and the paper top position reaches the paper feed roller so that the paper skew is adjusted then the f r solenoid is turned off the paper feed roller starts turning and the paper is fed to the transfer roller in the drum toner assy p.55
Forms a uniform charge on the drum surface 1 corona wire generates the ion charge on the drum p.56
Afterwards the paper is ejected from the fixing unit by the heat roller and the pressure roller in the fixing unit the paper eject actuator detects whether the paper is ejected correctly or not p.56
After the printing image on the exposure drum is transferred onto the paper the paper is fed to the fixing unit to fix unfixed toner onto the paper p.56
After the paper exits from the heat roller the paper is turned by the rear cover and ejected face down into the top output tray through the eject roller assy p.56
2 grid spreads the ion charge evenly over the drum surface p.56
Transfers the toner image to the paper from the drum surface p.56
Removes the paper dust or dirt on the surface of the exposure drum p.56
Generates the latent electrostatic image and develops the image on the drum surface p.56
Develops the electrostatic latent image on the exposure drum with toner and forms the visible image p.57
Toner life end mode p.57
Toner cartridge p.57
The life of the toner cartridge is starter 1 500 standard 2 500 pages at the 5 coverage in the case of low duty printing toner life end is indicated by displaying the toner life end message on the lcd before toner runs out because the developer roller surface or other toner sealing is worn out due to rotation of the rollers the upper limit of the drum rotation is 45 000 3000 sheets x 15 rotations the following graph shows the number of printable pages in the case of a4 printing p.57
Printable pages p.57
Page job p.57
Confidential 3 1 2 p.57
2 3 4 5 6 7 8 9 10 11 12 p.57
When the new toner detection switch detects that the toner cartridge is replaced with a new one the developing bias voltage is initialized at the same time the toner used for the printer has a property that print density is light first and gradually darker in the course of usage the developing bias controls the toner property so that the print density is constant from first to last p.59
To always obtain a print result of a constant density the printer counts the number of print pages immediately after the toner cartridge is replaced and changes the bias voltage according to the accumulated number of prints with the toner cartridge the bias voltage is changed with the steps described below 1 when the new toner sensor detects that the toner cartridge is replaced with a new full one the developing bias is set to 450v initialized 2 after that the bias voltage is stepped down according to the number of prints p.59
The counter resetting method during indication of toner life end depends on the cause of toner life end and the condition of the inserted toner cartridge refer to the following table for details p.59
Confidential 3 1 4 p.59
1 the laser beam radiated from a laser diode inside the laser unit are concentrated into a constant width by a slit in the co lens cell and then reflected by a polygon mirror rotating at high speed 2 the laser beam reflected by the polygon mirror are refracted by the theta lens and radiated from the right through to the left end of the reflection mirror as the polygon mirror rotates at this time blur of the vertical direction of the laser beam by inclination of a polygon mirror is corrected by passing a cyl lens p.60
The primary charge uses a corona wire but since the drum is positively charged only less than 1 10 of the usual quantity of ozone is generated compared with the negatively charged drum the level of ozone expelled from the printer is therefore not harmful to the human body applicable safety standards have been complied with p.60
The drum is charged to approximately 900v by an ion charge which is generated by the primary charger the charge is generated by ionization of the corona wire which has a dc bias from the high voltage power supply applied to it the flow of the ion charge is controlled by the grid to ensure it is distributed evenly on the drum surface the aluminum drum sleeve in the exposure drum is grounded p.60
After the drum is positively charged it is exposed to the light emitted from the laser unit p.60
The laser beams reflected by the reflection mirror go straight toward the exposure drum below it then expose the exposure drum the area exposed to the laser beam is the image to be printed the surface potential of the exposed area is reduced forming the electrostatic image to be printed p.61
Developing causes the toner to be attracted to the electrostatic image on the drum so as to transform it into a visible image the developer consists of a non magnetic toner the developer roller is made of conductive rubber and the supply roller which is also made of conductive sponge rotate against each other the toner is charged and carried from the supply roller to the developer roller the toner adheres to the developer roller and is conveyed to the exposure drum at an even thickness controlled by the blade the toner is nipped between the developer roller and the drum and developed onto the latent image on the drum the electrostatic field between the drum and the developer roller which is dc biased from the high voltage power supply creates the electrostatic potential to attract toner particles from the developer roller to the latent image area on the drum surface p.61
Developing p.61
This chapter describes how to transfer data left in the machine to be sent for repair the service personnel should instruct end users to follow the transfer procedure given in this chapter if the machine at the user site cannot print received data due to the printing mechanism defective end users can transfer received data to another machine to prevent data loss p.66
Contents p.66
Chapter 4 transfer of data left in the machine to be sent for repair p.66
Transferring received fax data p.67
End page sample end page sample p.68
Cover page sample p.68
This chapter also covers screw tightening torques and lubrication points to which the specified lubricants should be applied during reassembly jobs p.70
Contents p.70
Chapter 5 disassembly reassembly and lubrication p.70
At the start of a disassembly job you check the disassembly order flow that guides you through a shortcut to the object components p.70
This chapter details procedures for disassembling and reassembling the machine together with related notes the disassembly order flow provided enables you to see at a glance the quickest way to get to component s involved p.70
Disassembly reassembly p.72
0 8 1 main frame r taptite bind b m4x12 p.73
0 5 1 main frame l taptite bind b m4x12 p.73
Disassembly flowchart p.75
Confidential 5 4 p.75
1 open the front cover and remove the drum toner assy p.76
1 disconnect ac cord from the machine p.76
3 remove the separation pad holder assy and the separation pad spring p.77
2 remove the paper from the paper tray p.77
1 close the front cover and pull out the paper tray p.77
Note remove the a section of the rear cover while opening the rear cover slightly p.78
1 remove the rear cover p.78
2 remove the paper eject actuator and the eject actuator spring p.79
1 remove the rear chute cover p.79
1 open the front cover p.80
Side cover l p.80
Confidential 5 9 p.80
2 remove the two bind b m4x12 taptite screws and then remove the side cover l p.80
1 remove the two bind b m4x12 taptite screws and then remove the side cover r p.81
4 disconnect the two connectors of the scanner unit from the main pcb p.82
3 disconnect the two connectors of the adf unit from the main pcb p.82
2 remove the one cup s m3x6 taptite screw and adf fg harness and fb fg harness p.82
1 open the adf unit and scanner unit p.82
Confidential 5 12 p.83
8 remove the two lf springs from the adf cover p.83
7 release the two hooks from the adf cover and remove the pressure roller assy 7 release the two hooks from the adf cover and remove the pressure roller assy p.83
6 remove the two pins and remove the adf cover p.83
5 close the adf unit and scanner unit p.83
14 remove the four cup b m3x10 taptite screws p.85
13 remove the separate roller shaft assy and bushing from the adf unit p.85
12 close the adf unit p.85
15 release the three hooks a to remove the upper document chute p.85
17 remove the separation rubber from the adf plate spring p.86
16 remove the separation rubber assy from the upper document chute p.86
Note when re connecting the connectors put them through the holes on the adf unit before connectin p.87
20 release the hook on the adf unit and remove the ejection roller assy p.87
19 release the two hooks to remove the lower document chute p.87
18 remove the two cup b m3x10 taptite screws from the lower document chute p.87
22 remove the adf unit ejection spring from the adf unit 22 remove the adf unit ejection spring from the adf unit p.88
21 remove the two ejection rollers from the pressure roller shaft p.88
Confidential 5 18 p.89
26 release the two hooks b and remove the ejection roller bearing from the ejection roller assy p.89
25 release the two hooks a and remove the the ejection roller assy from the lower 25 release the two hooks a and remove the the ejection roller assy from the lower document chute p.89
24 remove the lf roller assy from the lower document chute p.89
23 release the two hooks and remove the resin bearing p.89
28 remove the drive frame assy from the lower document chute p.90
27 remove the two cup b m3x10 taptite screws and one cup s m3x6 taptite screw from the lower document chute p.90
30 remove the adf motor harness from the adf motor p.90
29 remove the one bind s m3x6 taptite screw from the drive frame assy to remove the adf motor p.90
Note when re assembling drive frame assy assemble it so that the arm assy is at the top p.91
31 remove the document rear actuator from the lower document chute p.91
34 remove the adf sensor harness assy p.92
33 release the two hooks a on the lower document chute to remove the adf sensor pcb assy p.92
32 remove the document front actuator from the lower document chute p.92
40 release the hook to remove the document cover assy p.93
39 remove the one bind b m4x12 taptite screw from the document cover sub assy p.93
38 open the adf unit p.93
37 remove the document spring from the lower document chute p.93
36 remove the pins and remove the document hold p.93
35 turn the lower document chute upside down p.93
43 remove the two pressure rollers from the pressure roller shaft p.94
42 remove the pressure roller assy p.94
41 remove the two springs p.94
46 remove the one bind b m4x12 taptite screw to remove the hinge arm p.95
45 remove the hinge from the hinge arm p.95
44 remove the three cup b m3x10 taptite screws to remove the hinge assy l p.95
Pull arm pull arm guide lock claw pull arm spring p.96
Confidential 5 25 p.96
3 remove the pull arm springs and remove the pull arms r l from the pull arm guides p.96
2 release the hook to remove the scanner unit side of the pull arms r l p.96
1 open the scanner unit p.96
Scanner unit p.97
Confidential 5 26 p.97
2 remove the scanner unit from the machine p.97
2 release the four hooks p.97
1 remove the four cup b m3x10 taptite screws from the scanner unit p.97
1 disconnect the flat cable from the main pcb p.97
4 release the three hooks to remove the panel unit from the scanner unit p.98
3 disconnect the connector from the panel pcb assy p.98
6 release the three hooks a to remove the panel pcb from the panel cover p.98
5 remove the lcd harness from the panel pcb p.98
Note when re assembling the rubber key make sure that the key works correctly p.99
Confidential 5 28 p.99
8 release the two hooks a to remove the backlight guide p.99
7 remove the rubber key p.99
Confidential 5 29 p.100
9 remove the diffusion film p.100
10 release the two hooks a to remove the lcd p.100
2 remove the one pan s p washer m3 x6 screw from the ncu shield cover to remove the ncu shield plate p.101
1 remove the two bind b m4x12 taptite screws and one pan s p washer m3 x6 screw from the ncu unit p.101
4 remove the two cup s m3x6 taptite screws from the ncu shield cover to remove the ncu pcb assy p.102
3 remove the ncu harness assy p.102
1 disconnect the connector of the speaker from the main pcb p.102
3 release the one hook to remove the speaker hold spring p.103
2 release the three hooks to remove the speaker cover p.103
Confidential 5 32 p.103
Confidential 5 33 p.104
4 remove the speaker assy p.104
1 remove the bind b m4x12 taptite screw and then remove the rear cover stopper p.104
Note re assemble the inner chute while pushing onto the pinch roller of the inner chute with the eject roller of the joint cover assy p.105
Confidential 5 34 p.105
3 remove the inner chute p.105
2 remove the two bind b m4x12 taptite screws and the rear chute cover spring p.105
Confidential 5 35 p.106
Caution there is a danger of explosion if the battery is incorrectly replaced do not replace the battery do not disassemble recharge or dispose of in fire used battery should be disposed of according to local regulations 5 remove the four bind b m4x12 taptite screws and then remove the joint cover assy p.106
4 remove the battery assy and disconnect the connector p.106
Front cover 5 5 front cover p.107
Confidential 5 36 p.107
3 slide the front cover assy to the direction of the arrow shown in the figure below to remove it p.107
2 release the hook a on the front cover assy from the chute p.107
1 release the hook of the drive release cam from the front cover assy p.107
5 remove the paper stopper s from the paper stopper l p.108
4 remove the paper stopper l p.108
Note note when re assembling the chute base check that the bind b m4x12 taptite screws a and b shown in the figure above are secured correctly p.109
2 remove the six bind b m4x12 taptite screws and then remove the chute base p.109
1 turn the printer upside down p.109
Take the drum toner unit out from the printer check that the distance between the floor and the separation roller collar of the pickup roller holder assy is 45 to 47 mm by using the plate jig if not re assemble the chute base p.110
Confidential 5 40 p.111
6 remove the f r roller shaft assy p.111
5 remove the bush f r p.111
4 release the hook and remove the gear 52 p r p.111
3 remove the spring extension p r from the gear 52 p r p.111
7 remove the link lever from the hook of the pickup roller holder assy p.112
Note the pickup roller holder spring is assembled on the bottom of the pickup roller holder assy be careful not to lose the spring p.112
8 remove the pickup roller holder assy p.112
2 remove the two cup b m4x12 taptite screws and then remove fixing unit p.113
1 disconnect the heater harness connector and thermistor harness connector p.113
Note be sure not to touch the pressure roller 3 remove the two pr spring p.113
4 remove the pressure roller assy pressure roller pr arm assy pr bush from the fuser frame p.113
Note be careful not to damage the heat roller when removing the separate claw assy p.114
6 release each hook of the springs from the fuser frame and remove the four separate claw assys p.114
5 remove the two pr arm assy and two pr bush from the pressure roller p.114
9 remove the halogen heater p.115
8 remove the heat roller p.115
7 remove the two pan s p washer m3x8 screws p.115
Note when re assembling the heat roller assemble the hr bush onto the fuser frame referring to the figure below p.116
Note when re assembling the halogen heater put the halogen heater onto the fuser frame so that the terminal of the heater harness is at the top and secure the screws in the order shown in the figure below p.116
12 remove the thermistor assy harness from the four hooks p.117
13 remove the cup b m3x12 taptite screw and then remove the thermistor assy p.117
11 remove the two hr bush p.117
10 remove the hr gear p.117
Note when re assembling the thermistor assy to the fuser frame ensure the direction of the thermistor assy is correct referring to the figure below p.118
1 disconnect the three connectors from the high voltage ps pcb assy p.119
High voltage ps pcb assy p.119
Confidential 5 48 p.119
4 remove the high voltage ps pcb from main frame l p.119
3 remove the two bind b m4x12 taptite screws and the two cup s m3x6 taptite screws p.119
2 disconnect the high voltage ps pcb harness from the main pcb p.119
Note when replacing the main pcb refer to adjustments and updating of settings required after parts replacement in chapter 6 p.120
4 remove the main pcb from main frame l p.120
3 remove the two flat s m3x8 taptite screws p.120
2 remove the five cup s m3x6 taptite screws and fg harness assy 6 p.120
1 disconnect the thirteen connectors from the main pcb p.120
Note when replacing the main pcb refer to adjustments and updating of settings required after parts replacement in chapter 6 p.121
4 remove the main pcb from main frame l p.121
3 remove the two flat s m3x8 taptite screws p.121
2 remove the five cup s m3x6 taptite screws and fg harness assy 6 p.121
1 disconnect the thirteen connectors from the main pcb p.121
1 remove the duct film p.122
Ps pcb unit p.122
Confidential 5 51 p.122
7 remove the lv insulation sheet p.122
6 remove the lv shield plate cover from the main frame r p.122
5 remove the two cup s m3x6 taptite screws p.122
4 remove the pan s p washer m3 x 6 screws and ncu fg harness p.122
3 remove the pan s p washer m3 x 6 screws and fg harness assy 5 p.122
2 remove the pan s p washer m3 x 6 screw and fg harness assy 1 p.122
9 remove the bind b m4x12 taptite screw and then remove the lv shield plate p.123
8 remove the pan s p washer m3 x6 screw and then remove the ground wire p.123
10 remove the two flat s m3x8 taptite screws and then remove the inlet harness assy p.123
Note when disconnecting the connectors disconnect the regist sensor pcb connector and toner led pcb unit assy connector first lift up the ps pcb unit from the lv shield plate and disconnect the main pcb connector p.124
12 disconnect the three connectors from the ps pcb unit and then remove the ps pcb unit p.124
11 remove the two cup s m3x6 taptite screws p.124
2 remove the four cup s m3x6 taptite screws b p.125
1 remove the cup s m3x6 taptite screw a and fg harness assy 6 p.125
Laser unit p.125
Confidential 5 54 p.125
3 remove the laser unit p.125
Note when replacing the laser unit replace the barcode label attached on the gear plate calking assy with a new one supplied with a new unit p.126
Another barcode label supplied with a new unit is spare make sure to throw it out p.126
5 remove the two cup s m3x6 taptite screws and then remove the air duct p.126
4 remove the filter assy from the air duct p.126
1 remove the two bind b m4x12 taptite screws and then remove the sub chute assy p.127
Note when re assembling the link lever insert the end of the link lever into the main frame l referring to the figure below p.128
2 pull the a section outwards and remove the link lever p.128
1 turn the printer body upside down p.128
2 remove the tail edge spring from the tail edge actuator p.129
2 remove the regist front spring from the regist front actuator p.129
1 remove the tail edge actuator with the tail edge spring p.129
1 remove the regist front actuator with the regist front spring p.129
1 remove the bind b m3x6 taptite screw p.130
Regist sensor pcb assy p.130
Confidential 5 59 p.130
2 remove the regist rear actuator p.130
2 release the harness from the hook and remove the regist sensor pcb assy p.130
1 remove the regist rear spring p.130
3 release the harness from the hook and then remove the fan motor 60 unit from the main frame r p.131
2 remove the base plate p.131
1 remove the three bind b m4x12 taptite screws and three fg harness assy 1 4 5 p.131
2 remove the led holder from the toner led pcb assy p.132
1 remove the toner led pcb assy from the main frame r p.132
New toner sensor p.133
2 release the hook and remove the new toner actuator from the main frame l p.133
1 remove the new toner actuator spring p.133
1 release the two hooks and remove the new toner sensor from the main frame l p.133
1 remove the cup b m3x6 taptite screw and then remove the toner sensor pcb assy p.134
1 release the two hooks and remove the cover sensor from the main frame l p.134
Main motor assy p.135
Confidential 5 64 p.135
3 remove the three cup s m3x6 taptite screws and then remove the main motor assy p.135
2 remove the five bind b m4x12 taptite screws and then remove the gear plate calking assy p.135
1 remove the hvps insulation sheet p.135
2 remove the p r solenoid assy the p r solenoid lever and the solenoid release spring p r p.136
1 remove the develop joint from the gear plate calking assy p.136
1 remove the bind b m3x10 taptite screw p.136
Note the gear assy contains the small gears be careful not to lose them by disassembling the gear assy p.137
F r solenoid assy p.137
Confidential 5 66 p.137
1 remove the gear assy from the main frame l p.137
Confidential 5 67 p.138
3 remove the f r solenoid assy the f r solenoid lever and the solenoid release spring f r p.138
2 remove the bind b m3x10 taptite screw p.138
1 remove the two bind b m4x12 taptite screws and then remove the main frame l p.139
Main frame r p.140
Confidential 5 69 p.140
1 remove the three bind b m4x12 taptite screws and then remove the main frame r p.140
Laser unit p.141
Harness routing p.141
Fg harness assy 1 fg harness assy 5 p.141
Confidential 5 70 p.141
Regist sensor pcb assy p.142
Fg harness assy 6 p.142
Confidential 5 71 p.142
Toner led pcb assy p.143
Fan motor 60 unit p.143
Confidential 5 72 p.143
Toner sensor pcb assy p.144
P r solenoid assy f r solenoid assy p.144
Confidential 5 73 p.144
Panel unit p.145
New toner sensor cover sensor battery harness p.145
Confidential 5 74 p.145
Document scanner p.146
Confidential 5 75 p.146
Adf unit p.146
Ncu pcb p.147
Ncu fg harness p.147
Confidential 5 76 p.147
Speaker assy p.148
Confidential 5 77 p.148
Pg2 pg 661 2 mm dia ball p.149
Lubrication p.149
Bg4 kanto kasei bg mu 4 mm dia ball p.149
Contents p.151
Chapter 6 adjustments and updating of settings required after parts replacement p.151
This chapter details adjustments and updating of settings which are required if main pcb and some other parts have been replaced p.151
If you replace the main pcb p.152
If you replace the laser scanner unit assy p.153
If you replace the document scanner unit p.153
For the cleaning procedures of the drum unit and toner cartridge refer to the user s guide p.155
Chapter 7 cleaning p.155
This chapter describes the maintenance mode which is exclusively designed for the purpose of checks settings and adjustments using the keys on the control panel you can customize the eeprom according to the shipment destination of the machine concerned in addition you can perform operational checks of the lcd control panel pcb or sensors perform a print test display the log information or error codes and modify firmware switches wsw p.157
Contents p.157
Chapter 8 maintenance mode p.157
Entry into the maintenance mode p.158
List of maintenance mode functions p.159
User access to the maintenance mode p.160
Detailed description of maintenance mode functions p.162
Scanning compensation data list p.164
7 confidential p.164
Cover page sample p.178
End page sample end page sample p.178
23 confidential p.180
This chapter details error messages and codes that the incorporated self diagnostic functions display if any error or malfunction occurs if any error message appears refer to this chapter to find which components should be checked or replaced the latter half of this chapter provides sample problems that could occur in the main sections of the machine and related troubleshooting procedures this will help service personnel pinpoint and repair defective components p.188
Contents p.188
Chapter 9 error indication and troubleshooting p.188
Error indication p.189
Troubleshooting p.203
Image defects p.215
Confidential 9 27 p.215
6 black vertical streaks 1 6 black vertical streaks 1 7 black horizontal stripes 1 8 black vertical streaks 1 9 white vertical streaks p.215
20 downward fogging of solid black 1 21 horizontal lines 1 22 light rain 1 23 ghost 1 24 toner specks p.215
15 white spots 1 16 black spots 1 17 black band 1 18 gray background 1 19 hollow print p.215
10 white horizontal streaks 1 11 faulty registration 1 12 poor fixing 1 13 image distortion 1 14 faint print p.215
1 light 1 2 dark 1 3 completely blank 1 4 all black 1 5 dirt on the back of paper p.215
I 2 dark p.217
I 3 completely blank p.218
Laser scanner unit assy p.218
Interlock lever p.218
I 5 dirt on the back of paper p.220
I 6 black and blurred vertical streaks p.221
I 7 black and blurred horizontal stripes p.222
Yes clean the electrodes at both sides 4 p.223
User check 1 check the paper used meets the recommended paper specifications a rough surfaced paper damp paper or thick media can cause the problem 2 check that the appropriate media type is selected in the printer driver 3 the problem may disappear by itself try printing multiple pages to clear this problem especially if the printer has not been used for a long time 4 the drum unit may be damaged install a new drum unit p.223
Remedy p.223
Possible cause p.223
I 9 white vertical streaks p.223
Developing bias contact failure p.223
Are the developing bias contacts between the printer body and toner cartridge dirty p.223
I 11 faulty registration p.224
I 12 poor fixing p.225
I 14 faint print p.226
I 13 image distortion p.226
Yes remove and carefully shake the toner cartridge horizontally p.226
Toner cartridge 2 does the problem happen immediately after replacing the toner cartridge with a new one p.226
Scanner window dirty 3 is the scanner window dirty yes clean the scanner window with a soft dry cloth p.226
Scanner ld emission failure scanner motor rotation failure p.226
Scanner connection failure p.226
Remedy p.226
Printer installation 1 is the printer placed horizontally no place the printer on a flat surface p.226
Possible cause p.226
No secure the unit correctly and tighten the screws p.226
No connect the harness correctly p.226
Laser unit installation 1 is the laser unit secured to the frame incorrectly check if there is any play p.226
Laser unit failure 4 is the problem solved by replacing the laser unit yes replace the laser unit p.226
Is the scanner harness connected properly check if it is coming loose p.226
Is the laser diode or the scanner motor defective no replace the laser unit p.226
I 15 white spots p.227
1 remove the toner cartridge from the drum unit place the printing samples in front of the drum unit and find the exact position of the image defect p.228
Note clean the drum unit as follows p.228
I 16 black spots p.229
I 17 black band p.230
I 18 gray background p.231
I 19 hollow print p.232
I 23 ghost p.234
Printer body paper tray p.235
Location of grounding contacts p.235
Drum unit p.235
Confidential 9 47 p.235
Serial numbering system p.249
Location location p.249
Individual machines have a serial number label for the machine itself and a property label for the head carriage unit this section lists the coding information for those serial numbers and property codes p.249
1 serial number label for the machine itself p.249
App 1 2 confidential p.250
2 laser unit serial label p.250
Regarding x delay and y delay it indicates required delay amount for writing in each of main x and sub y scanning direction p.250
Location location p.250
If you use parallel interface p.252
A2 installing the update data to the machine p.252
If you use usb cable p.254
A2 setting id codes to machines p.260
Eeprom customizing codes p.262
Mfc7420 7820n dcp7010 7020 7025 p.263
Appendix 4 firmware switches wsw p.263
These selectors allow you to limit the transmission speed range in v 4 mode by masking the desired symbol rate s transmission speeds assigned to the symbol rates are listed on the next page the setting made by these selectors will limit the setting made by selectors 1 through 4 on wsw39 if selector 3 is set to 1 to mask the 3429 symbols second when the first transmission speed choice is 33600 bps specified by selectors 1 through 4 of wsw39 for example then the allowable maximum transmission speed will be limited to 31200 bps if selector 8 is set to 1 to mask the 2400 symbols second when the first transmission speed choice is 33600 bps then the allowable maximum transmission speed remains 33600 bps if selector 8 is set to 1 to mask the 2400 symbols second when the first transmission speed choice is 21600 bps specified by selectors 1 through 4 on wsw39 then the allowable maximum transmission speed remains 21600 bps but the minimum transmission speed will be limited to 4800 bps p.307
Selector no function setting and specifications p.307
Note wsw40 takes effect only when the v 4 mode is permitted wsw19 selector 7 in models supporting v 4 mode p.307
8 masking of symbol rate s p.307
2 not used p.307
Confidential p.319
Appendix 6 circuit diagrams p.320
Mfc7420 7820n dcp7010 7020 7025 p.320
Confidential p.321
A ncu pcb mfc742 p.321
Confidential p.324
A ncu pcb mfc7820 p.324
Confidential p.325
B power supply pcb 100 p.325

Brother MFC-7420R [178/327] End page sample end page sample

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