Apple imac 17 inch flat panel User Manual

iMac (17-inch Flat Panel) Troubleshooting - 9
 General Information
Logic Board Battery
Important: Apple highly recommends removing the battery when handling the logic board. Make 
sure to use proper ESD protection when handling modules.
The battery on the logic board controls the stored system settings, such as date and time. It is only 
necessary to test the battery when you can’t power on the computer, or the date and time are reset 
every time the AC power is removed. 
The battery is also used to...

10 - iMac (17-inch Flat Panel) Troubleshooting
 General Information 4. Connect the power cord and power up the system again. 
Warning:
 Whenever the bottom housing is opened for service, you must do two things:
1. You must clean and reapply thermal paste to the thermal pipe surface.
2. You must tighten the four torx bolts on the base unit to a minimum of 17 in.– lbs. Failure to follow 
either of these steps could cause the computer to overheat nd damage internal components. 
Refer to the next topic,...

iMac (17-inch Flat Panel) Troubleshooting - 11
 General Information
Thermal Paste Application
The following instructions explain how to apply thermal paste to the thermal pipe in the iMac (17-inch Flat 
Panel) computer. Failure to follow these instructions could cause the computer to overheat and damage 
internal components.
Tools
This procedure requires the following tools:
• Plastic stylus or plastic spatula to remove the old thermal paste
• Plastic stylus or plastic spatula to spread the thermal...

12 - iMac (17-inch Flat Panel) Troubleshooting
 General Information
Procedure
1. Thoroughly clean the original thermal film from the four mating surfaces circled below. Use a plastic 
stylus to scrape the surfaces clean. Note:  Do not use an abrasive material or liquid cleaner.
2. Squeeze a drop of thermal paste onto the thermal pipe locations circled below. 
3. Close the bottom housing.
 Warning: The bottom housing has four torx screws that must be tightened to at least 17 in.-lbs. If you 
do not have a...

iMac (17-inch Flat Panel) Troubleshooting - 13
 General Information
Thermal Pad Replacement Instructions
Whenever the logic board is separated from the bottom housing, you must install new thermal pads to three 
surfaces on the bottom housing. The thermal pads help cool components on the logic board. Failure to apply 
these pads whenever the logic board is separated from the bottom housing could cause these parts to 
overheat. Short term separation, where the thermal pads are not handled excessively 
(an...

14 - iMac (17-inch Flat Panel) Troubleshooting
 Symptom Charts
Symptom Charts
How to Use the Symptom Charts
The Symptom Charts included in this chapter will help you diagnose specific symptoms related to the 
product. Because cures are listed on the charts in the order of most likely solution, try the cures in the 
order presented. Verify whether or not the product continues to exhibit the symptom. If the symptom 
persists, try the next cure. 
Note:  If you have replaced a module, reinstall the original...

iMac (17-inch Flat Panel) Troubleshooting - 15
No Power Symptom Charts
No Power 
No fan, no hard drive noise, and the screen is black.
1. Verify the power outlet is good. Plug a different device into the socket to ensure there is power, or plug 
computer into another outlet.
2. Check the power cord. Use a known good power cord.
3. Check connection of the power cord on both ends. Verify that the plug is securely plugged into both the 
A/C outlet and back of the computer.
4. Remove keyboard, mouse, and...

16 - iMac (17-inch Flat Panel) Troubleshooting
No Power Symptom Charts 11. Remove the bottom housing. Warning:  Whenever the bottom housing is opened for service, you must 
do two things:
• You must clean the original thermal film from the surfaces joining the thermal interface layer and 
reapply thermal paste to the thermal pipe.
• The bottom housing has four torx screws that must be tightened to at least 17 in.-lbs. If you do not 
have a torque driver, you will have to make sure these screws are...

iMac (17-inch Flat Panel) Troubleshooting - 17
No Power Symptom Charts 15. Check power supply output. Disconnect the diagnostic power cable from the power supply connector, 
and measure power at the power supply connector by touching the black probe to the ground pin, and 
using the red probe to measure power at the pins indicated in the graphic below. Did you measure +12v 
at each point? If yes, replace the logic board. If no, replace the power supply.
16. Replace the inverter board.
17. Replace the...

18 - iMac (17-inch Flat Panel) Troubleshooting
No Video Symptom Charts
No Video 
Screen is dark, fan is running and the hard drive is spinning. You may hear the startup 
chime as well.
1. Reset parameter RAM. Press Command-Option-P-R during startup before “Welcome to Macintosh” 
appears.
2. The system software could be damaged. Start up from the system CD that came with the computer.
3. Remove the user access panel. With the unit powered on, check if a red LED (shown below) is visible 
in the access...