Troubleshooting Symptom/Cure Tables:Startup Problems Before the Finder Appears
No Power In a “No Power” situation, the system is completely dead. There is no LED, no hard
drive power, and the screen is completely black. (Refer to “Testing for Power” ear-
lier in this chapter for instructions on how to test for power at each component refer-
enced in this procedure.)
Possible Cause Possible Fix
Bad power cord, connec-
tion, or outlet.
- Verify the power outlet is good.
- Try a known-good power cord to determine if the
existing power cord could be the problem. Make sure
the power cord is connected securely at both ends.
Improperly aligned front
power-on button
-If the front power-on LED is not centered properly
within the inner button, the inner power button can
become stuck between the LED and the inner bezel
resulting in a no power, intermittent shut down, or
sleep situation. Refer the LED Alignment procedure in
the Adjustments chapter or to TIL article 58622 for
steps to resolve the LED alignment issue.
Bad USB keyboard. - Verify the keyboard cable is connected properly to the
computer.
- Disconnect the keyboard and power on the system via
the button on the front of the computer. Do you have
power to the system now?
Yes: The keyboard is bad. Replace the keyboard.
No: Go to next step.
The PMU chip needs to be
reset.
- Press the PMU chip on the logic board with the AC
power cord disconnected. (See “The PMU Chip” and
“Resetting the PMU on the Logic Board” mentioned
earlier in this chapter.)
- Connect the power cord and power on the system again.
Do you have power to the system now?
Yes: Test the unit with MacTest Pro and return the
computer to the customer.
No: With the AC power cord connected, reset the PMU
chip again. Do you have power to the system now?
Yes: The battery is likely bad, check the battery.
No: Go to the next step.