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HP 2420 Service Manual - Page 86

Step 1: Primary charging, Step 2: Laser beam exposure,

UPC - 829160289205

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Step 1: Primary charging Dc and ac biases are applied to the primary charging roller, which transfers a uniform negative potential to the photosensitive drum. Figure 5-9. Primary charging Step 2: Laser beam exposure The laser beam scans the photosensitive drum to neutralize negative charges on parts of the drum. An electrostatic latent image is formed on the drum where negative charges were neutralized. 72 Chapter 5 Theory of operation ENWW

Section	Page
Product Information	15
Chapter contents	15
Printer configurations	16
HP LaserJet 2400 Series printer base models	16
Features	18
Specifications	22
Physical specifications	22
Electrical specifications	23
Acoustic emissions	24
Operating environment	24
Media specifications	25
Supported types and sizes of print media	25
Paper and print media	26
Printing and paper storage environment	27
Envelopes	28
Envelopes with double side seams	28
Envelopes with adhesive strips or flaps	28
Envelope margins	29
Envelope storage	29
Labels	29
Transparencies	29
Hewlett-Packard limited warranty statement	30
Print Cartridge Limited Warranty Statement	31
HP LaserJet printing supplies	32
Declaration of conformity	33
Country-/region-specific safety statements	34
Laser safety statement	34
Canadian DOC statement	34
Japanese VCCI statement	34
Korean EMI statement	34
Finnish laser statement	35
Installation	37
Chapter contents	37
Operating environment	38
Interface ports	38
Software	39
Operating systems and printer components	39
Printer drivers	40
Software for Macintosh computers	41
Operation	43
Chapter contents	43
Control panel	45
Control-panel layout	45
Control-panel buttons	46
Control-panel lights	47
Control-panel language	48
Printing control-panel menus	48
Selecting which tray is used for printing	49
Understanding tray order	49
Customizing tray 1 operation	50
Printing by type and size of media (locking trays)	51
Feeding media from tray 1 manually	52
Selecting the correct fuser mode	53
Using the embedded Web server	54
Opening the embedded Web server	54
Information tab	55
Settings tab	55
Networking tab	56
Other links	56
Using HP Web Jetadmin software	57
Using the HP Toolbox	58
Supported operating systems	58
Supported browsers	58
To view the HP Toolbox	59
Status tab	59
Troubleshooting tab	60
Alerts tab	60
Documentation tab	61
Device Settings window	61
Toolbox links	61
Other links	61
Uninstalling the HP Toolbox	62
To uninstall the HP Toolbox by using the Windows desktop shortcut	62
Checking the printer configuration	62
Menu map	62
Configuration page	63
Supplies status page	65
PS or PCL font list	66
Managing the print cartridge	67
HP print cartridges	67
Non-HP print cartridges	67
Print-cartridge authentication	67
Print-cartridge storage	67
Print-cartridge life expectancy	68
Checking the supply level	68
Cartridge-low and cartridge-out conditions	69
Maintenance	71
Chapter contents	71
Cleaning the printer	72
Cleaning the outside	72
Cleaning the paper path and print-cartridge areas	72
Cleaning the fuser	74
Theory of operation	75
Chapter contents	75
Introduction	76
Internal components	77
Timing	78
Engine control system	80
Laser/scanner system	82
Pickup/feed/delivery system	83
Image-formation system	85
Step 1: Primary charging	86
Step 2: Laser beam exposure	86
Step 3: Developing	87
Step 4: Transfer	87
Step 5: Separation	88
Step 6: Fusing	88
Step 7: Drum cleaning	89
Print cartridge memory system	90
Removal and replacement	91
Chapter contents	91
Introduction	92
Removal and replacement strategy	92
Electrostatic discharge	92
User-replaceable parts	92
Required tools	92
Before performing service	93
Pre-service procedures	93
Parts removal order	94
Covers	95
Right-side cover	95
Back cover	96
I/O cover	99
Left-side cover	100
Top, right cover	102
Top cover	103
Front, right cover	104
Control panel	106
Formatter	108
Fuser	112
Laser/scanner	117
Right-side handle	120
ECU	122
Access plate	128
Power supply	129
Gear assembly	134
Tray 1 solenoid	138
Tray 2 solenoid	139
E-label reader (memory tag)	140
Face-down-roller shaft	142
Cartridge door	144
Transfer roller	147
Registration assembly	148
Tray 1 pickup roller	151
Tray 2 pickup roller	152
Separation pad	154
Troubleshooting	155
Chapter contents	155
Troubleshooting tree	157
Troubleshooting flowchart	158
1. Does the control-panel display show READY?	158
2. Can you print a configuration page?	159
3. Can you print from a program?	160
4. Does the job print as expected?	161
5. Does the printer select the correct trays?	162
Troubleshooting tools	163
Information pages	163
Embedded Web server	168
Gaining access to the embedded Web server	168
Printer Status and Alerts software	170
Control-panel menus	172
Using control-panel menus	172
Resets submenu	173
Diagnostics menu	173
Service menu (service PIN codes)	175
Printer resets and power-on modes	177
Cold reset	177
NVRAM initialization	178
Hard-disk initialization	178
Power-on bypass	179
Save + Restore	179
Test pages	180
Engine-test page	180
Formatter test page	180
Interface troubleshooting	181
Communications checks	181
EIO troubleshooting	181
Solving general printing problems	183
Clearing jams	187
Avoiding jams	187
Typical jam locations	188
Media handling problems	195
Multiple pages feed	195
Pages are wrinkled or folded	196
Pages are skewed	196
Understanding printer messages	197
Using the printer online Help system	197
Resolving persistent messages	197
Correcting print-quality problems	215
Print-quality checklist	215
Image-defect examples	215
Light print (partial page)	217
Light print (entire page)	217
Specks	218
Dropouts	218
Lines	219
Gray background	219
Toner smear	220
Loose toner	220
Repeating defects	221
Repeating image	221
Misformed characters	222
Page skew	222
Curl or wave	223
Wrinkles or creases	223
Vertical white lines	224
Tire tracks	224
White spots on black	225
Scattered lines	225
Blurred print	226
Random image repetition	226
Troubleshooting common Windows problems	227
Troubleshooting common Macintosh problems	228
Troubleshooting common PostScript problems	234
General problems	234
Specific errors	234
Printer component locations	236
Main assemblies	236
Main parts	237
Sensors and switches	238
Motors, fans, and solenoids	239
PCAs	240
500-Sheet paper feeder	241
Wiring diagrams	242
General timing diagrams	245
Parts and diagrams	247
Chapter contents	247
Ordering parts and supplies	248
Parts	248
Related documentation and software	248
Supplies	248
Accessories	249
Covers	252
Internal components	254
Tray 2 pickup assembly	268
Alphabetical parts list	270
Numerical parts list	276