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HP 5100 Service Manual - Page 75

Overcurrent overvoltage protection

UPC - 808736092500

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If a short circuit or other problems on the load side cause an excessive current flow from the +24 Vdc or +3.4 Vdc power supplies or generate abnormal voltage, the excess-current protection system and excess-voltage protection system automatically shut off the output voltage to protect the power supplies. If an excess-current or excess-voltage protection system is activated and the power supply circuit does not output dc voltage, it is necessary to turn the power off, correct the problem in the faulty load, then turn the printer on again. The circuit has two fuses that break and cut off the output voltage if excess-current flows through the ac line. Overcurrent overvoltage protection This circuit, located on the dc controller PCA, always monitors an abnormal rise in the fusing roller temperature. If an error occurs, this circuit puts out a signal to turn the relay (RL1) off and interrupt the power to the fusing roller heater. The circuit operates as follows. When the fusing roller heater temperature rises and the output voltage of the thermistor exceeds about 0.5 V (230° C), pin 7 of the comparator (IC304) goes "L." IC304 pin 1 goes "L," Q4 turns off, and then the relay (RL1) turns off. The printer has the following three protection functions to prevent incorrect activation of the fusing-roller heater. The central processing unit (CPU) monitors the thermistor voltage. If it is abnormal, the CPU identifies the fusing-roller heater error, turns the relay (RL1) off, and reports it to the formatter. If the fusing-roller heater temperature rises abnormally and the thermistor voltage falls below about 0.6 V (220° C), the safety circuit in the fusing-roller heater interrupts the power to the fusing heater regardless of the CPU output. If the fusing-roller heater temperature rises abnormally and the thermal fuse temperature exceeds 240° C, the thermal switch turns off and interrupts the power to the fusing-roller heater. Q1860-90918 Chapter 5 Functional information 73

Section	Page
Contents	5
Figures	11
Tables	15
Printer description	17
Overview	17
Printer features	18
Printer information	19
Identification	21
Model and serial numbers	21
Site requirements	22
Environmental and power requirements	22
Space requirements	23
Paper specifications	27
Supported types of paper	28
Guidelines for using paper	29
Labels	31
Transparencies	31
Vellum	31
Envelopes	31
Card stock and heavy paper	33
Safety information	34
Laser safety statement	34
Canadian DOC regulations	34
FCC regulations	34
Laser statement for Finland	35
Luokan 1 laserlaite	35
Material Safety Data Sheet	35
Environmental product stewardship	36
Service approach	37
Overview	37
Regulatory information	38
Service approach	38
Parts and supplies	38
Warranty	38
Limited warranty for the print cartridge	38
Service and support	39
Worldwide service and support offices	40
Printer operation	43
Overview	43
Using the control panel	44
Control panel layout	44
Control panel lights	44
Control panel keys	45
Settings and defaults	46
Control panel menus	47
Private/stored jobs menu	48
Information menu	49
Paper-handling menu	50
Print-quality menu	52
Printing menu	53
Configuration menu	55
I/O menu	57
EIO menu (HP LaserJet 5100tn and 5100dtn printers)	58
Resets menu	60
Service mode	61
Service menu	61
Setting the page count, maintenance count, and serial number	62
Cold reset paper size	64
Diagnostics	64
Clear event log	64
Testing the printer	65
Resetting the printer	65
Cold reset	65
Clearing NVRAM	65
Initializing the hard disk	65
System configuration	66
MS-DOS system configuration	66
Parallel MS-DOS commands	66
Printer I/O configuration	66
Parallel menu	66
Printer maintenance	67
Overview	67
Cleaning the printer and accessories	68
Cleaning spilled toner	69
Preventive maintenance	70
Reset maintenance count	70
Expected life of components	70
Functional information	71
Overview	71
Printer subsystems	73
Power supply system	74
Ac/dc power distribution	74
Overcurrent overvoltage protection	75
High-voltage power distribution	76
Toner-cartridge detection	77
Dc controller system	77
Laser and scanner drive	78
Paper-motion monitoring and control	78
Solenoids, sensors, clutches, and switches	78
Engine test	78
Motors	79
Formatter system	80
PowerSave	80
Resolution Enhancement technology	80
EconoMode	81
Input/output	81
CPU	81
Printer memory	82
Memory Enhancement technology	82
Page protect	83
PJL	83
PML	83
Control panel	83
Image-formation system	84
Toner cartridge	85
Photosensitive drum	86
Writing the image	88
Developing the image	89
Transferring the image	90
Image fusing/variable fusing temperature	91
Paper feed system	93
Clutches and sensors	94
Printing from Tray 1	94
Printing from Tray 2	95
Printing from the optional 500-sheet and 250sheet Trays	97
Paper jam	99
Duplexer	100
Paper jam in the duplexer	102
Basic sequence of operation	103
Removing and replacing parts	107
Overview	107
User-installable accessories	109
Memory upgrade	109
Checking memory installation	111
Installing EIO cards or mass-storage devices	112
Paper-handling accessories	112
Before you begin	113
Replacing printer parts	113
Removing loose toner	113
Required tools	113
Parts removal order	114
Covers	115
Rear door and rear output bin	115
Fuser	116
Top cover	117
Control panel overlay and control panel	119
Toner cartridge door assembly	121
Front cover and Tray 1	122
Front cover pins	123
Face-down cover	124
Left and right side covers	125
Tray 1 inner cover	126
Right and left corner covers	128
Internal assemblies	129
Transfer-roller assembly	130
Paper-handling PCA	133
Main gear assembly	136
Pickup gear assembly	138
Tray 1 pickup solenoid	139
Fan	140
Formatter assembly	141
Tray 1 roller	142
Tray 1 separation pad	143
Tray 2 pickup roller	144
Tray 2 separation pad	145
Paper-feed roller assembly	146
Dc controller and power supply	148
Paper-feed belt assembly	150
Tray 1 shaft	152
Tray 2 shaft	154
Tray 1 lift plate	156
Paper guide	157
Top-of-page sensor	158
Face-down bin-full sensor lever	159
Accessory interface connector	160
Registration assembly	161
Upper delivery assembly	163
Delivery roller	164
Laser/scanner assembly	166
Main motor	167
Toner cartridge guides	168
Power inlet assembly	169
Optional 250-sheet feeder	170
Separation pad	170
Pickup roller	171
Sensing flag	172
Control PCA	173
Paper-size spring assembly	175
Optional 500-sheet feeder	176
Covers and base frame	176
Tray indicator assembly	178
Left front corner cover installation	179
500-sheet feeder feed roller	180
500-sheet feeder pickup roller	181
500-sheet feeder PCAs	182
500-sheet feeder power connector	183
500-sheet feeder separation roller	184
Troubleshooting	185
Overview	185
Troubleshooting process	186
Troubleshooting process flow	187
Troubleshooting the printing system	189
Preliminary operating checks	189
Power on	190
Engine test	192
Display	192
Event log	193
Printer messages	195
General paper-path troubleshooting	204
Information pages	206
Image quality	209
Image system troubleshooting	226
Interface troubleshooting	227
Reference diagrams	229
Locations of components	229
Sensors and signals	238
Dccontroller inputs and outputs	254
Parts and diagrams	259
Overview	259
Ordering parts and supplies, and getting support	261
Related documentation and software	261
Support	261
Ordering parts	261
Ordering consumables	261
Accessories and supplies	262
Common hardware and replacement cables	263
Diagrams and parts lists	264
Alphabetical parts list	292
Numerical parts list	296
Index	301
Numerics	301
A	301
B	302
C	302
D	303
E	303
F	304
G	305
H	305
I	305
J	305
K	306
L	306
M	306
N	307
O	307
P	307
Q	308
R	308
S	309
T	310
U	311
V	311

Match case Limit results 1 per page

Q1860-90918

Chapter 5 Functional information

If a short circuit or other problems on the load side cause an excessive current flow from the

+24

Vdc or +3.4 Vdc power supplies or generate abnormal voltage, the excess-current

protection system and excess-voltage protection system automatically shut off the output voltage

to protect the power supplies.

If an excess-current or excess-voltage protection system is activated and the power supply

circuit does not output dc voltage, it is necessary to turn the power off, correct the problem in the

faulty load, then turn the printer on again.

The circuit has two fuses that break and cut off the output voltage if excess-current flows through

the ac line.

Overcurrent overvoltage protection

This circuit, located on the dc controller PCA, always monitors an abnormal rise in the fusing

roller temperature. If an error occurs, this circuit puts out a signal to turn the relay (RL1) off and

interrupt the power to the fusing roller heater. The circuit operates as follows.

When the fusing roller heater temperature rises and the output voltage of the thermistor exceeds

about 0.5 V (230° C), pin 7 of the comparator (IC304) goes “L.” IC304 pin 1 goes “L,” Q4 turns

off, and then the relay (RL1) turns off.

The printer has the following three protection functions to prevent incorrect activation of the

fusing-roller heater.

The central processing unit (CPU) monitors the thermistor voltage. If it is abnormal, the CPU

identifies the fusing-roller heater error, turns the relay (RL1) off, and reports it to the

formatter.

If the fusing-roller heater temperature rises abnormally and the thermistor voltage falls below

about 0.6 V (220° C), the safety circuit in the fusing-roller heater interrupts the power to the

fusing heater regardless of the CPU output.

If the fusing-roller heater temperature rises abnormally and the thermal fuse temperature

exceeds 240° C, the thermal switch turns off and interrupts the power to the fusing-roller

heater.