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Ricoh FW780 Service Manual - Page 66

Overheat Protection, and cuts the +24 volt supply to ac drive board. The fusing lamp then turns off.

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8.3.2 Overheat Protection The overheat protection circuit on the main board turns off the fusing lamp if the temperature goes too high. The input from TH1 (Hot Roller Thermistor) goes to pin 3 of IC17 as well as to the CPU. As the temperature of TH1 increases, its resistance decreases and therefore the voltage at pin 3 of IC17 increases. If this voltage becomes greater than the voltage at pin 2, the output at pin 1 becomes HIGH. Q1 then turns off and cuts the +24 volt supply to ac drive board. The fusing lamp then turns off. The overheat protection circuit becomes effective at about 215°C. TF1 provides overheat protection in case a short bypasses the control and drive circuits. This fuse will open if it reaches approximately 192°C. SM 2-30 A163

Section	Page
A163 SERVICE MANUAL	5
Legend/Documentation History	11
Important Safety Notices	13
Table of Contents	15
Overall Machine Information	23
Specifications	25
Paper Path	27
Drum Processes	28
Mechanical Component Layout	30
Drive Layout	31
Electrical Component Layout	32
Detailed Section Descriptions	35
Drum	37
Drum Characteristics	37
Drum Drive	38
Charge	39
Overview	39
Charge Corona Circuit	40
Corona Unit Ventilation	41
Exposure	42
Overview	42
Paper and Original Feed	43
FL Regulator Control	47
Manual ID Control	48
Development	49
Overview	49
Drive Mechanism	50
Crossing-Mixing	51
Toner Density Control	52
Development Bias	55
Toner Supply	56
Image Transfer and Paper Separation	57
Pre-Transfer Lamp (PTL)	57
Image Transfer	57
Paper Separation	57
Pick-Off Mechanism	58
T/S Corona Circuit	59
Cleaning	60
Overview	60
Collection of Used Toner	61
Quenching	62
Fusing and Paper Exit	63
Overview	63
Drive Mechanism	64
Fusing Temperature Control	65
Temperature Control	67
Energy Saver Function	70
Fusing Entrance Guide Height	71
Roll Cutting Rail	72
Roll Cutting Rail	72
Installation	73
Environment	75
Minimum space requirements	76
Machine level	76
Power source	77
Installation procedure - copier	78
Installation procedure - table	86
Installation procedure - roll cutting rail	88
Service Tables	91
Preventive Maintenance Schedule	93
PM table	93
Regular PM procedure	96
Service Tables	99
Test points	99
Variable resistors	99
Service Tools	100
Service program mode	100
Input/output check mode	119
Power on initial setting mode	122
Jam Code List	123
Access procedure	123
Jam code table	123
Special Tools and Lubricants	125
Service Remarks	126
Drum unit	126
Charge corona	127
Optics	128
Development	128
Transfer and separation	129
Cleaning unit	129
Fusing unit	130
Original feed	130
Paper feed	130
Roll feeder	131
Others	131
Replacement and Adjustment	133
Exterior Covers	135
Optics	136
Original feed unit removal	136
Exposure glass removal	137
Exposure lamp removal	137
Fiber optics array removal	138
Light sensor replacement	139
Development	140
Development unit removal	140
Developer removal	142
Toner density sensor replacement	143
PTL replacement	144
Development bias voltag adjustment	145
Drum	147
Drum unit removal	147
Drum replacement	148
Cleaning blade replacement	149
Charge corona unit removal	150
Charge corona wire replacement	151
Pick-off pawl unit removal	152
Grid voltage adjustment	153
Drum current adjustment	154
Fusing	160
Fusing unit removal	160
Hot roller replacement	162
Pressure roller replacement	163
Pressure roller thermistor replacement	164
Pressure roller stripper unit replacement	164
Hot roller stripper unit replacement	164
Hot roller thermistor replacement	165
Fusing thermofuse replacement	165
Fusing temperature adjustment	166
T&S Corona Unit	167
T&S corona unit removal	167
Transfer and separation corona wire replacement	168
Others	170
Ozone filter replacement	170
Anti-condensation heater installation	171
Copy Quality Adjustment	172
Light sensor adjustment	173
Image bias adjustment	174
Toner density adjustment	175
Registration adjustment	175
Troubleshooting	177
Copy Quality Troubleshooting	179
Low image density	179
Uneven copy image	180
Dirty background	181
Black line or band	182
Entirely blank copy	183
Paper creasing	184
Service Call Condition	185
SC code E-1: exposure lamp abnormal	185
SC code E-2: fusing thermofuse open	185
SC code E-3: hot roller thermistor open	186
SC code E-4: hot roller thermistor short	186
SC code E-5: pressure roller thermistor open	186
SC code E-6: pressure roller thermistor short	187
SC code E-7: fusing overheat	187
SC code E-8: fusing warm-up error	188
SC code E-9: toner density sensor abnormal	188
SC code E-10: main motor abnormal	189
SC code E-11: toner density sensor adjustment	189
Blown Fuse Table	190
Power supply unit	190
Roll Feeder	191
Specifications	193
Mechanical Component and Drive Layout	194
Electrical Component Descriptions	195
Mechanical Operation	197
Basic operation	197
Cutter unit opening and closing mechanism	199
Cutter operation	200
Service Tables	201
Test points	201
Blown fuse condition	201
Installation Procedure	202
Replacement and Adjustment	209
Exterior cover removal	209
Cutter unit removal	210
Paper feed roller replacement	211
Paper feed motor timing belt tension adjustment	212
Cut length adjustment	213
Roll feed paper skew adjustment	214
A251/A252 SERVICE MANUAL	215
TABLE OF CONTENTS	217
IMPORTANT SAFETY NOTICES	219
A163, A251, A252, A174 COMPARISON CHART	223
OVERALL INFORMATION	225
OVERALL MACHINE INFORMATION	227
SPECIFICATIONS	227
PAPER PATH	229
MECHANICAL COMPONENT	230
DRIVE LAYOUT	232
ELECTRICAL COMPONENT DESCRIPTIONS	233
DETAILED DESCRIPTIONS	235
DETAILED SECTION DESCRIPTIONS	237
DRUM	237
EXPOSURE	238
DEVELOPMENT	240
FUSING AND PAPER EXIT	241
INSTALLATION	243
INSTALLATION	245
INSTALLATION REQUIREMENTS	245
INSTALLATION PROCEDURE	248
SERVICE TABLES	269
SERVICE TABLES	271
SERVICE TOOLS	271
JAM CODE LIST	281
SERVICE REMARKS	285
REPLACEMENT AND ADJUSTMENT	287
REPLACEMENT AND ADJUSTMENT	289
OPTICS	289
DRUM UNIT	294
FUSING	295
T & S CORONA UNIT	297
COPY QUALITY ADJUSTMENT	299
TROUBLESHOOTING	301
TROUBLESHOOTING	303
SERVICE CALL CONDITION	303
BLOWN FUSE TABLE	304
B047/B048 SERVICE MANUAL	305
LEGEND/DOCUMENTATION HISTORY	309
COMPARISON OF MAJOR SPECIFICATIONS	319
OVERALL INFORMATON	321
OVERALL MACHINE INFORMATION	323
SPECIFICATIONS	323
PAPER PATH	325
MECHANICAL COMPONENTS	326
ELECTRICAL COMPONENTS	328
DETAILED DESCRIPTIONS	331
DETAILED SECTION DESCRIPTIONS	333
EXPOSURE	333
PAPER AND ORIGINAL FEED (B048 ONLY)	333
DEVELOPMENT	336
TONER DENSITY CONTROL	336
CLEANING	338
USED TONER COLLECTION	338
FUSING AND PAPER EXIT	339
OVERVIEW	339
TEMPERATURE CONTROL	340
ENERGY STAR COMPLIANT MACHINES (ALL THE DESTINATION)	341
INSTALLATION	343
INSTALLATION	345
INSTALLATION REQUIREMENTS	345
ENVIRONMENT	345
MINIMUM SPACE REQUIREMENTS	346
MACHINE LEVEL	346
POWER SOURCE	347
INSTALLATION PROCEDURE	348
COPIER	348
TABLE (B439)	357
COPY TRAY (B440)	359
ROLL FEEDER1 AND 2 (B435/B436)	363
ROLL CUTTING RAIL (B437)	372
SERVICE TABLES	373
SERVICE TABLES	375
SERVICE TOOLS	375
SERVICE PROGRAM MODE	375
INPUT/OUTPUT CHECK MODE	397
JAM CODE LIST	399
JAM CODE TABLE	399
SERVICE REMARKS	403
AC DRIVE BOARD	403
REPLACEMENT AND ADJUSTMENT	405
REPLACEMENT AND ADJUSTMENT	407
DRUM UNIT	407
DRUM REPLACEMENT	407
FUSING	408
HOT ROLLER THERMISTOR REPLACEMENT	408
FUSING THERMOFUSE REPLACEMENT	408
FUSING TEMPERATURE ADJUSTMENT	409
COPY QUALITY ADJUSTMENT	410
REGISTRATION ADJUSTMENT	410
TROUBLESHOOTING	411
TROUBLESHOOTING	413
SERVICE CALL CONDITIONS	413
SC CODE DESCRIPTIONS	413
BLOWN FUSE TABLE	417
POWER SUPPLY UNIT	417
ROLL FEED UNIT B435/B436	419
OVERALL MACHINE INFORMATION	421
SPECIFICATIONS	421
ELECTRICAL COMPONENT DESCRIPTIONS	422
DETAILED SECTION DESCRIPTIONS	423
MECHANICAL OPERATION	423
BASIC OPERATION	423
ROLL EDITION DETECTION	425
DRIVE MECHANISM	425
CUTTER OPERATION	426
REPLACEMENT AND ADJUSTMENT	427
CUTTER UNIT REPLACEMENT	427
ROLL FEED LEADING EDGE SENSOR REPLACEMENT	428
ROLL FEED UNIT REMOVAL	429
ROLL FEED CLUTCH REPLACEMENT	430
ROLL FEED MOTOR REPLACEMENT	431
ROLL END SENSOR REPLACEMENT	432
CUT LENGTH ADJUSTMENT	433
SIDE REGISTRATION ADJUSTMENT	434
TECHNICAL SERVICE BULLETINS	435
Ricoh TSBs	437
-001 - Parts Catalog Updates	437
-002 - Grounding Plate Spring and Bushings	438
-003 - Field Service Manual Insert	439
-004 - Energy Star Modification (Details)	440
-005 - Parts Catalog Updates	444
-005r -Parts Catalog Updates	445
-006 - Field Service Manual Insert	446
-007 - Parts Catalog Updates	447
-008 - Original Stoppers	449
-009 - Parts Catalog Additions	450
-010 - Fusing Temperature Adjustment Procedure	451
-011 - Pressure Roller Evaluation Procedure	453
-012 - PhotoInterruptor	454
-013 - Parts Catalog Updates	455
-014 - T/S Corona Unit	457
-015 - Blank Copies	458
RGC Technical Service Bulletins	459
A163	459
-001 - Spring Replacement - Charge Corona Unit	459
-002 - Updated Energy Star Requirements	461
-003 - Small Cap	462
-004 - Installation Check - Grounding Wires	463
-005 - Overtoning	464
-006 - Original Jam	465
-007 - Service Manual - Insert	466
-008 - Power Pack (C.G.B.)	469
-009 - Spacer	470
-011 - Left and Right Paper Guide	471
A571	473
-001 - Small Cap	473
A836	474
-001 - Rear Copy Tray	474
B047	475
-001 - Original Feed Right Plate and Fiber Optics	475
-002 - Service Manual Insert	476
-003 - Toner Hopper Joint Shaft	478
-004 - Receiving Tray Cover	480