Apple IMAC Service Source - Page 147

3. Whenever the17-inch LCD display (661-2715) is replaced, a display shield/gasket kit (076-0958) must be installed on the new panel. Instructions for installing the shield/gasket kit are included with the new LCD panel. 4. The LED and microphone are part of the 17-inch display bezel (922-5297); they cannot be ordered separately. 5. The LED functions differently on the iMac (17-inch Flat Panel). The LED does not light up when the power is on; however, the LED should pulse when the computer is in Sleep mode.Important: If you are replacing the display, be sure to install the new display shield and EMI gaskets that come with the new LCD panel. Installation instructions are included with the new display panel. Additional display shields/ gasket kits are also available separately as a kit, part number 076-0958. 6. Important: Whenever the logic board is separated from the bottom housing, you must install new thermal pads to two 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 exception would be if you are simply testing the logic board and only detach it for a few minutes), does not require replacement. Refer to "Thermal Pad Installation" in this chapter for detailed information. Refer to the Take Apart chapter, "Thermal Pad Installation." 7. Whenever the bottom housing is opened for service, you must do two things: 1.You must clean the original thermal film from the surfaces joining the thermal interface layer and reapply thermal paste to the thermal pipe. 2. You must tighten the four torx screws on the bottom housing to a minimum of 17 in.-lbs. If you do not have a torque driver, you will have to make sure these screws are tightened by hand FIRMLY, BUT NOT FORCIBLY. Or, purchase the service tool (076-0899) in order to ensure the thermal pipe is firmly mated with the top base. If the bottom housing is not securely attached to the base in this fashion, the CPU may overheat and become damaged. Failure to follow either of these steps could cause the computer to overheat and damage internal components. Refer to the topic, "Thermal Paste Application" for detailed information. 8. A service stand, 076-0898, is available from Apple Service to hold the unit while you service the computer. 2 - iMac (USB 2.0) Troubleshooting General Information