Specifications

iMac (Early 2006 17-inch) Troubleshooting — Symptom Charts 140
should hear the fans go quiet.
While the computer is o, with your left hand, hold down the Apple key, the Option key
next to it, and the letter “R” key on the keyboard. When you have these keys all pressed
down, push the power button with your right hand and then quickly move that hand
to hold down the letter “P” on the keyboard. Keep these four keys pressed while the
computer starts up.
Make sure you hold down the four keys (P - R - Apple - Option) while the computer is
starting up. When you hear the computer’s start up chime for the second time, you can
let go of the keys on the keyboard.
If you didn’t hear at least two startup chimes, go to the top of this section and begin
again. It’s important that you hear two startup chimes when performing this procedure.
This indicates that you have successfully reset the computer’s PRAM (Parameter RAM).
3. Does the computer display video after successfully resetting the computer’s PRAM?
Yes: Restart the computer from the Apple menu and make sure the computer is now
working correctly.
No: Continue to next step.
4. Make sure the machine is powered o; power o the machine by holding in the Power Button
on the rear of the machine. Turn on the machine. Observe the white LED on the front bezel
during startup; it should go out after a few moments. Did the LED go o?
Yes: If the LED went o, this indicates that the main logic board has communicated with the
LCD display for video signal and your main logic board should be good. You can conrm by
connecting an external monitor and checking to see that you have video out. Go to Step 8.
No: Continue with the next step to reset system power management (SMC).
5. Reset the SMC (Formerly SMU).
Turn o the computer by choosing Shut Down from the Apple menu, or by holding the
power button until the computer turns o.
Unplug all cables from the computer, including the power cord.
Wait 15 seconds.
Plug in the power cord while simultaneously pressing and holding the power button on
the back of the computer.
Let go of the power button.
Press the power button once more to start up your iMac.
Does the computer display video after successfully resetting the SMC?
Yes: Press and hold the power button until the computer powers o. Start the computer
again and conrm that front LED is reliably going o. If the computer still has no video but
the LED is reliably going o, continue with step 8.
No: Go to the next step.
6. Unplug the iMac and remove the SDRAM. Replace with known good SDRAM. Plug the iMac
back in and power the unit on. Does the front LED go o after a few moments now?
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