3.

Press power button while

Yes

Power supply functioning and

 

 

monitoring diagnostic LEDs.

 

logic board detects supply

 

 

Verify if LED #2 turns ON and

 

voltages. Go to Won’t Start

 

 

remains ON after pressing

 

Up symptom flow.

 

 

the power button. You may

 

 

 

 

alternately check for a power

 

 

 

 

No

Go to step 5.

 

 

request signal between pin 12

 

 

 

 

 

 

and pin 1 of logic board.

 

 

 

 

 

 

 

 

4.

Disconnect AC cable. Remove

Yes

Reseat misconnected cable(s),

P16

 

glass and LCD panel, and

 

or replace damaged one(s).

 

 

carefully inspect the connectors

 

 

 

 

between AC inlet and power

 

 

 

 

supply, then DC connectors and

No

Replace DC power cable

X03

 

cables between power supply

 

harness.. Go to step 8.

 

 

and logic board, for damage or

 

 

 

 

poor connections.

 

 

 

 

 

 

 

 

5.

Inspect power button and

Yes

Go to step 6.

 

 

verify if it is properly connected

 

 

 

 

No

Reconnect power button.

 

 

to the logic board.

 

 

 

 

 

 

6.

Disconnect power button from

Yes

Power button is functioning

 

 

logic board. Inspect cable and

 

correctly. Reconnect power

 

 

connector for damage. Using a

 

button to logic board and

 

 

multimeter (set as ohmmeter),

 

go to step 7.

 

 

verify continuity between the

 

 

 

 

No

Power button faulty. Replace

X14

 

two pins of the power button

 

when it is pressed.

 

rear housing (which includes

 

 

 

 

power button).

 

 

 

 

 

 

7.

Press power button and Verify

Yes

Power supply functioning. If

 

 

if system turns ON. You may

 

system still won’t boot, go

 

 

alternately check for presence

 

to Won’t Start Up symptom

 

 

of a 12V DC signal between

 

flow.

 

 

pin 11 and pin 1 of logic board

 

 

 

 

No

Replace DC power cable

X03

 

when power button is pressed.

 

 

harness. Go to step 8.

 

 

 

 

 

 

 

 

 

 

8.

Press power button and verify if

Yes

Issue solved with replaced DC

 

 

system turns ON.

 

power cable harness.

 

 

 

 

 

 

 

 

No

Replace power supply.

P01

 

 

 

Go to step 9.

 

 

 

 

 

 

9.

Press power button and verify if

Yes

Issue solved with replaced

 

 

system turns ON.

 

power supply.

 

 

 

 

 

 

 

 

No

Reinstall power supply and

M01

 

 

 

replace logic board.

 

 

 

 

 

 

Note: If No Power symptom persists after all steps have been followed use minimum configuration troubleshooting to proceed. Try disconnecting hard drive(s), optical drive, AirPort, Bluetooth, and SD card modules to determine if one of them is preventing the power supply from functioning.

2010-09-09

iMac (27-inch, Mid 2010) Symptom Charts — Startup and Power  36

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Image 36
Apple MD094LL/A manual To Won’t Start Up symptom