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Apple IMAC User Manual - Page 86

Testing for Power, At the AC Outlet, At the Logic Board, General/ Testing for Power - 4

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Troubleshooting General/ Testing for Power - 4 Testing for Power The iMac requires trickle voltage (+5 TRKL) in order to poweron. If you are experiencing power problems in the iMac unit, you will want to test for trickle power at various points in the system to pinpoint the location of the problem and to determine whether or not the power supply is functioning normally. If you have trickle power in the system, the odds are your power supply is OK. In general, you should test for power at the AC outlet first. Next, it is best to start at the end (in this case, the logic board) and trace power backwards through the system. In this way, you will be able to immediately pinpoint which component is failing. Note: It is highly unlikely that the power filter board will fail; therefore, you need not test for power at this component. Following is the order in which you should test for power in the system: At the 1) AC outlet, 2) logic board, 3) power filter cable, 4) power supply board, and 5) power supply fuse. Testing for power requires that you remove certain parts from the computer. Refer to the Take-Apart chapter for instructions on removing parts. At the AC Outlet First, unplug the keyboard from the computer. Then, using a known-good power cord, power-on the system using the power button on the front of the computer. If the system powers on, you can assume the AC outlet is good and the problem is with the keyboard. If the system still won't power on, try connecting to a different AC outlet. If the unit powers on this time, you most likely have a problem with the AC outlet. If you still have no power, you will need to test for power at internal points inside the iMac. At the Logic Board With the iMac placed with the CRT face down on a soft surface, remove the bottom access cover and then remove the logic board/ mass storage chassis to access the logic board. Note: You will need a volt meter to test for power on the logic board. Refer to the picture on the next page to locate the necessary test point referenced in the following procedure.

Section	Page
iMac	1
Hot Issues	2
Introduction	3
Mixed Memory Types	4
HFS Plus Formatted Drives	6
Forcing a Restart	7
External Displays Not Supported	8
iMac Updates	9
CD-ROM Door Not Latching Closed	11
Revision vs. Version Part Numbers	12
Version 2 Service Parts	13
New CD-ROM Drive Released (7/99)	14
Basics	16
Overview	17
Features	46
Views	66
Repair Strategy/Warranty	74
Specifications	80
Introduction	81
Spec Database at Service Source Online	81
Spec Database on Service Source CD	81
Troubleshooting	82
General	83
Block Diagram	84
Power Flow	85
Power Supply Board Fuse	85
Testing for Power	86
At the AC Outlet	86
At the Logic Board	86
At the Power Supply to Power Filter Cable	88
At the Power Supply Board	89
At the Power Supply Board Fuse	91
The Cuda Chip	92
Resetting the Logic Board	93
Power-On Self Test	94
Video Flow	95
Sound In Flow	95
Sound Out Flow	96
Processor Module	96
Logic Board Battery	96
HFS Plus Formatted Drives	97
Testing the Modem	98
Symptom Charts	99
How to Use the Symptom Charts	99
No Power	99
Video Problems	100
Error Beeps	104
Memory Error Dialog Box	105
Flashing Question Mark	105
Can’t Wake From Sleep	106
System Hangs/Freezes During Boot	107
Networking Problem	108
CD-ROM Not Showing on Desktop/Can’t Open CD	109
CD-ROM Vibration	109
CD-ROM Door Not Latching Closed	110
Hard Drive Problems	111
Sound Out Problems	112
Sound In Problems	113
IrDA Problems	114
USB Problems	115
Cursor Problems	117
USB Printer Problems	117
Networked Printer Problems	118
Modem Not Recognized	120
Modem Dialing Problems	120
Modem Not Connecting	122
Modem Dropping Connection	122
Modem Performance Issues	124
Take Apart	125
General	126
Tools	127
Procedures	128
Lower Access Cover	129
Replacing the Lower Access Cover	132
Logic Board/Mass Storage Chassis	133
Replacing the Logic Board/Mass Storage Chassis	135
Logic Board	136
Ethernet Hardware ID Label	141
Reconnecting Logic Board Cables	142
Processor Card	143
Modem	148
I/O Panel	150
SDRAM	153
Processor Shield Frame	155
CD-ROM	157
CD-ROM Part Numbers	159
Replacing the CD-ROM Carrier	161
Removing the CD-ROM Bezel	163
Hard Drive	167
Replacing the Hard Drive Carrier	171
Power Filter Board	172
Fan	174
Audio/Video Interconnect Board	177
Bottom Rear Housing	181
Front Lower Panel	184
Speakers	189
IrDA Board	192
Headphone/Power Board	194
Front Outer Bezel	196
Front Inner Bezel	199
Top Rear Housing	203
EMI Shield	209
Analog/Video Board	211
Analog/Video Board, Ver. 2	217
Power Supply Board	223
Power Supply Board, Ver. 2	230
CRT	237
Microphone	242
I/O Door	244
Serial Number and Ethernet Address	245
CRT Frame	246
Installing a Microphone Gasket	251
Upgrades	255
SDRAM	256
VRAM	262
Adjustments	267
Adjustment Tools	268
Light Meter Setup	269
Model R77	269
Model L-248	273
Model 246	274
Geometry	275
Saving Geometry Settings for Multiple Resolutions	276
Video	277
Cutoff	278
White Balance	287
Focus	292
Exploded View	296
Logic Board/Mass Storage Chassis Exploded View	297
Colored Service Parts Matrix	298
iMac Screw Matrix	299
Wiring Diagram, Analog/Video 661-2080 and Power Supply 661-2081	300
Wiring Diagram, Ver. 2 Analog/Video 661-2166 and Ver. 2 Power Supply 661-2167	301
Additional Procedures	302
Resetting the CD-ROM Eject Mechanism	303
Emergency Handbook Includes troubleshooting, hard disk repair, and software installation information for your iMac	306
Contents	308
1 Problems Starting Up7	308
Problems7	308
Computer won’t start up, restart, or shut down7	308
Single icon appears in middle of screen8	308
Computer beeps8	308
Computer freezes8	308
Message appears9	308
Normal desktop doesn’t appear10	308
Hard disk icon doesn’t appear on desktop10	308
Computer starts up from wrong disk11	308
Solutions11	308
Take notes.11	308
Wake up your computer.11	308
Restart the computer.12	308
Force your computer to restart.12	308
Shut down the computer.12	308
Force your computer to shut down.13	308
Quit open applications.13	308
Make sure your computer is getting power.13	308
Make sure the screen is properly adjusted.13	308
Make sure external devices are properly connected and turned on.14	308
Check RAM disk settings in the Memory control panel.15	308
Increase the memory available for system software.15	308
Reset the window display.16	308
Re-bless the System Folder.16	309
Make sure you’re using the correct disk as a startup disk.16	309
CD disc is jammed.17	309
Resolve system extension conflicts.17	309
Reset the PRAM.19	309
Make sure memory is installed correctly.20	309
Replace the computer’s backup battery.20	309
Test and repair the hard disk directory.21	309
Reinstall system software.21	309
Where to Find Onscreen Help22	309
MacOS Help22	309
MacOS Info Center22	309
2 Problems Using Your Computer23	309
Problems With Applications, Documents, and Memory23	309
Problems With Hard Disks, CDs, and Other Storage Media29	309
Problems With Hard Disks29	309
Problems With CD Drives and Discs30	309
Problems Using ISO 9660 or High Sierra Discs32	309
Problems Using Photo CDs33	309
Problems Playing Audio CDs33	309
Problems With USB Devices33	309
Problems Printing35	309
Performance and Other Problems36	309
Problems With Networks and File Sharing39	309
Problems With Sound and Video41	309
3 Starting Up From a CD45	309
Starting Up From the Software Install CD45	309
4 Testing and Repairing Your HardDiskDirectory47	309
Repairing Corrupted Data on Your Disk47	309
If Disk First Aid Cannot Correct the Problem48	309
Updating the Hard Disk Drivers49	309
Initializing a Hard Disk49	309
MacOS Extended Format50	309
Testing Your Hard Disk for Physical Damage50	310
5 Reinstalling Your Computer’s Software53	310
Reinstalling System Software53	310
Before Installing System Software53	310
Reinstalling Mac OS System Software54	310
Selecting Which Software to Install55	310
Performing a Clean Installation58	310
Reinstalling Your Custom Extensions, Fonts, and Control Panels59	310
If the Clean Installation Didn’t Solve the Problem60	310
Problems During Installation60	310
Responding to Messages About Your Hard Disk62	310
Reinstalling Individual Applications62	310
Restoring All Original Software63	310
Before Restoring Your Software63	310
Restoring In Place63	310
Erasing Your Hard Disk64	310
6 Contacting Apple for Help65	310
Obtaining Information via the World Wide Web65	310
Have This Information Available Before Calling66	310
Using the Apple System Profiler66	310
Index67	310
Problems Starting Up	312
Problems	312
Computer won’t start up, restart, or shut down	312
Single icon appears in middle of screen	313
Computer beeps	313
Computer freezes	313
Message appears	314
Normal desktop doesn’t appear	315
Hard disk icon doesn’t appear on desktop	315
Computer starts up from wrong disk	316
Solutions	316
Take notes.	316
Wake up your computer.	316
Restart the computer.	317
Force your computer to restart.	317
Shut down the computer.	317
Force your computer to shut down.	318
Quit open applications.	318
Make sure your computer is getting power.	318
Make sure the screen is properly adjusted.	318
Make sure external devices are properly connected and turned on.	319
Check RAM disk settings in the Memory control panel.	320
Increase the memory available for system software.	320
Reset the window display.	321
Re-bless the System Folder.	321
Make sure you’re using the correct disk as a startup disk.	321
CD disc is jammed.	322
Resolve system extension conflicts.	322
Reset the PRAM.	324
Make sure memory is installed correctly.	325
Replace the computer’s backup battery.	325
Test and repair the hard disk directory.	326
Reinstall system software.	326
Where to Find Onscreen Help	327
MacOS Help	327
MacOS Info Center	327
Problems Using Your Computer	328
Problems With Applications, Documents, and Memory	328
Problems With Hard Disks, CDs, and Other Storage Media	334
Problems With Hard Disks	334
Problems With CD Drives and Discs	335
Problems Using ISO 9660 or High Sierra Discs	337
Problems Using Photo CDs	338
Problems Playing Audio CDs	338
Problems With USB Devices	338
Problems Printing	340
Performance and Other Problems	341
Problems With Networks and File Sharing	344
Problems With Sound and Video	346
Starting Up From a CD	350
Starting Up From the Software Install CD	350
When You’re Done With the CD	351
Testing and Repairing Your HardDiskDirectory	352
Repairing Corrupted Data on Your Disk	352
If Disk First Aid Cannot Correct the Problem	353
Updating the Hard Disk Drivers	354
Initializing a Hard Disk	354
MacOS Extended Format	355
Testing Your Hard Disk for Physical Damage	355
Reinstalling Your Computer’s Software	358
Reinstalling System Software	358
Before Installing System Software	358
Reinstalling Mac OS System Software	359
Selecting Which Software to Install	360
Standard Installation	361
Custom Installation	361
Performing a Clean Installation	363
Reinstalling Your Custom Extensions, Fonts, and Control Panels	364
If the Clean Installation Didn’t Solve the Problem	365
Problems During Installation	365
Responding to Messages About Your Hard Disk	367
Reinstalling Individual Applications	367
Restoring All Original Software	368
Before Restoring Your Software	368
Restoring In Place	368
Erasing Your Hard Disk	369
Contacting Apple for Help	370
Obtaining Information via the World Wide Web	370
Have This Information Available Before Calling	371
Using the Apple System Profiler	371
Index	372

Match case Limit results 1 per page

Troubleshooting

General/ Testing for Power - 4

Testing for Power

The iMac requires trickle voltage (+5 TRKL) in order to power-

on. If you are experiencing power problems in the iMac unit, you

will want to test for trickle power at various points in the system

to pinpoint the location of the problem and to determine whether

or not the power supply is functioning normally. If you have

trickle power in the system, the odds are your power supply is

OK.

In general, you should test for power at the AC outlet first. Next,

it is best to start at the end (in this case, the logic board) and

trace power backwards through the system. In this way, you will

be able to immediately pinpoint which component is failing.

Note:

It is highly unlikely that the power filter board will fail;

therefore, you need not test for power at this component.

Following is the order in which you should test for power in the

system:

At the 1) AC outlet,

2) logic board,

3) power filter

cable,

4) power supply board, and

5) power supply fuse.

Testing for power requires that you remove certain parts from

the computer. Refer to the Take-Apart chapter for instructions on

removing parts.

At the AC Outlet

First, unplug the keyboard from the computer. Then, using a

known-good power cord, power-on the system using the power

button on the front of the computer. If the system powers on, you

can assume the AC outlet is good and the problem is with the

keyboard. If the system still won’t power on, try connecting to a

different AC outlet. If the unit powers on this time, you most

likely have a problem with the AC outlet. If you still have no

power, you will need to test for power at internal points inside the

iMac.

At the Logic Board

With the iMac placed with the CRT face down on a soft surface,

remove the bottom access cover and then remove the logic board/

mass storage chassis to access the logic board.

Note

: You will need a volt meter to test for power on the logic

board. Refer to the picture on the next page to locate the necessary

test point referenced in the following procedure.