Service Cables

Three extension cables 076-0897 are required when troubleshooting the iMac with the bottom housing open, as shown below. Important Diagnostic service cables allow the unit to run while the bottom housing is open as shown above . However, the computer cannot run for more than five minutes with the bottom housing open. If it is open longer, the CPU may overheat and become damaged. A power cable B drive data cable C blind mate connector The PMU Power Management Unit is a microcontroller chip that...

Procedure

Gently remove the I O port covers from the logic board. Warning 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....

Apple Hardware Test

Apple Hardware Test is a diagnostic tool for detecting problems with Apple internal hardware components such as logic board, memory, modem, video RAM, and Apple AirPort Card. The test does not check externally connected hardware components such as USB or FireWire devices it also does not check nonApple devices such as third-party PCI cards. Note The most recent Apple Hardware Test software can be downloaded from the CD Images page on AppleCare Service Source go to the Service Source home page...

Thermal Paste Application

The following instructions explain how to apply thermal paste to the thermal pipe in the iMac Flat Panel computer. Failure to follow these instructions could cause the computer to overheat and damage internal components. This procedure requires the following tools Plastic stylus or nylon probe tool 922-5065 to remove the old thermal paste Thermal paste 922-4757 , each tube contains 4-5 applications 1. Thoroughly clean the thermal film from the mating surfaces circled below . Use a plastic...

Preliminary Steps

Internal Video Cable Imac Lamp

Before you begin, do the following Position the computer in the service stand. Before you begin, do the following Position the computer in the service stand. 1. Remove the plastic cable retainer and turn it over. Gently peel the fan gasket off the back of the cable retainer. Warning 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...