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HP 2500 Service Manual - Page 77

Developing stage, Step 3: developing

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Note Developing stage The developing cylinder comes in contact with the photosensitive drum to deposit toner onto the electrostatic latent image. The charges on the exposed area on the drum are shown as positive in figure 27. The charges are actually negative, but they are more positive than the charges on the developing cylinder. Figure 27. Developing block Step 3: developing Toner acquires a negative charge through friction from the developing cylinder and the blade. When the negatively charged toner comes in contact with the drum, the toner adheres to the electrostatic latent image. The image on the drum becomes visible because of the toner. Figure 28. Step 3: developing EN 4 Theory of operation 75

Section	Page
Contents	5
Figures	11
Tables	15
Product Information	17
Chapter contents	17
Introduction	18
Product configurations	18
Product specifications	19
Media specifications	22
Model and serial numbers	23
Printer overview	24
Front and left-side view	24
Back and right-side view	24
Warranty statements	25
Hewlett-Packard limited warranty statement	25
Limited warranty for the print cartridges and imaging drum	26
Regulatory statements	27
Declaration of Conformity	27
Laser safety statement	28
Canadian DOC statement	28
VCCI statement (Japan)	28
Korean EMI statement	28
Finnish laser statement	29
Installation and operation	31
Operating environment	32
Interface ports	33
Control panel features	34
Understanding supplies status	35
Understanding printer status	36
Selecting media	37
Input trays	37
Supported print media	38
Printer output paths	39
Top output bin	39
Rear output door	39
Loading media	40
Loading tray1	40
Loading optional tray2	41
Loading optional tray3	42
Using the embedded Web server	43
Information tab	44
Settings tab	44
Networking tab	44
Other links	45
Using printer status and alerts	46
Maintenance	47
Life expectancies of supplies	48
User-replaceable parts	49
Replacing the pickup roller and separation pad	49
Replacing the separation pad in tray 2 or in optional tray 3	53
Cleaning the printer	55
Cleaning the engine	55
Calibrating the printer	56
Managing supplies	57
Supplies life	57
Checking and ordering supplies	57
Storing supplies	58
Replacing and recycling supplies	58
HP policy on non-HP supplies	59
HP fraud hotline	59
Theory of operation	61
Chapter contents	61
Introduction	62
Engine control system	63
Basic sequence of operation	64
Power-on sequence	65
Motors and fans	66
Laser/scanner system	67
Pickup and feed system	68
Paper trays	69
Jam detection	70
Photosensors and switches	71
Solenoid and clutches	72
Printed circuit assemblies	73
Image formation system	74
Image formation process	75
Latent image formation stage	76
Developing stage	77
Transfer stage	78
Fusing stage	80
Print cartridge	84
Imaging-drum E-label	85
Removal and replacement	87
Introduction	89
Removal and replacement strategy	89
Electrostatic discharge	89
User-replaceable parts	89
Required tools	89
Before performing service	90
Pre-service procedures	90
Parts removal order	91
Removal and replacement	92
Imaging drum	92
Print cartridges	93
Jetdirect card	93
Fuser cover (and fuser)	94
Right- and left-side covers	95
Control panel	97
On-off switch	99
Interface cover	100
Formatter cage	101
Formatter	103
Fuser motor (J702)	105
Dc controller	106
Optional tray 2 (250-sheet tray)	108
Carousel motor (J704)	110
Front lower cover	111
Back cover	112
Top cover	113
Top door	115
Air duct and fan	117
Laser/scanner assembly	118
Front cover	120
Density sensor and top-of-page sensor	121
E-label reader (for imaging-drum E-labels)	122
Tray 1 (multipurpose tray)	124
Tray 1 separation pad assembly	126
Gear assembly	127
Waste-toner sensor	129
Rotary-drive assembly	130
Top plate	133
Print-cartridge carousel	136
Registration-roller assembly	141
Toner-catch tray	142
Transfer-roller plate	143
Transfer roller	144
Feed-drive shaft	145
ECU pan	146
Sub-high-voltage transformer PCA	149
High-voltage transformer PCA	150
Low-voltage PCA	151
Paper-top sensor	153
Fuser-wrap sensor	154
250-sheet feeder pickup roller	155
250-sheet feeder cover	156
250-sheet feeder PCA	157
500-sheet feeder pickup roller	158
500-sheet feeder cover	160
500-sheet feeder motor	161
Troubleshooting	163
Chapter contents	163
Basic troubleshooting	164
Clearing jams	166
Control panel light messages	171
Supplies Status lights	172
Printer Status lights	176
Attention with Ability to Continue secondary messages	179
Accessory error secondary messages	181
Service error secondary messages	183
Solving image-quality problems	185
Solving image-quality problems (all print jobs)	186
Solving image-quality problems (color print jobs)	193
Resolving problems that generated messages	196
Resolving problems that did not generate messages	197
Solving general printing problems	199
Solving PostScript (PS) errors	203
Solving common Macintosh problems	204
Rotating the print-cartridge carousel	206
Functional checks	207
Engine test	207
Half self-test functional check	208
Drum-rotation functional check	208
Heating element check	209
High-voltage power-supply check	209
Paper-path check	210
Service mode functions	211
Cold reset	211
NVRAM initializer	211
Troubleshooting tools	212
Demo page	212
Configuration page	212
Supplies Status page	213
General timing charts	214
Locations of connectors	217
Dc controller connections	220
Main wiring diagram	221
Repetitive image defect ruler	223
HPColor LaserJet 2500 Series Toolbox	224
Parts and diagrams	227
Chapter contents	227
Ordering parts and supplies	228
Parts	228
Related documentation and software	228
Supplies	228
Accessories	229
How to use the parts lists and diagrams	230
Assembly locations	231
Printer (without optional trays)	231
Covers	232
Internal assemblies	234
Front frame assembly	234
Internal Components (1 of 2)	236
Internal components (2 of 2)	238
Main drive assembly	240
Rear frame assembly	242
Middle frame assembly	244
Rotary (carousel) assembly	246
Power-supply base assembly	248
Fuser assembly	250
Rotary-drive assembly	252
PCA assemblies	253
Optional tray 2	254
Covers for optional tray 2	254
Center frame assembly—optional tray 2	256
Media tray—optional tray 2	258
Right cover assembly—optional tray 2	259
Optional tray 3	260
Covers for optional tray 3	260
Internal components—optional tray 3	262
Feed drive assembly—optional tray 3	264
Media tray—optional tray 3	266
Alphabetical parts list	268
Numerical parts list	275
Index	283
Numerics	283
A	283
B	283
C	283
D	284
E	284
F	284
G	285
H	285
I	285
J	285
K	285
L	286
M	286
N	286
O	286
P	287
Q	288
R	288
S	288
T	289
U	290
V	290
W	290

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4 Theory of operation

Developing stage

The developing cylinder comes in contact with the photosensitive drum to deposit toner onto the

electrostatic latent image.

Note

The charges on the exposed area on the drum are shown as positive in figure 27. The charges

are actually negative, but they are more positive than the charges on the developing cylinder.

Figure 27.

Developing block

Step 3: developing

Toner acquires a negative charge through friction from the developing cylinder and the blade.

When the negatively charged toner comes in contact with the drum, the toner adheres to the

electrostatic latent image. The image on the drum becomes visible because of the toner.

Figure 28.

Step 3: developing