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A2115 / 2019 / Processors from 3.0 GHz 6-core i5, up to 3.6 GHz 8-core i9. Released March 19, 2019.

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Hi iMac 27( 2019 A2115) - does not turn on!

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hi imac 27( 2019 A2115) - does not turn on! LED 2-3 is on

Please help - what does this mean?

diagnostic LEDs

1- of . 2-on. 3-on 4-of 5 -of

the fan sometimes spins slowly sometimes very quickly - the screen is black. There was a power surge

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what should I do? what exactly is my situation? change power supply?

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What are the 5 diagnostic LEDs?

This is from the Apple service manual:

Diagnostic LEDs

LED 1 - Indicates that the trickle voltage from the power supply has been detected by the main logic board. This LED will turn on when you connect the iMac to a working AC power source. The

LED will remain on as long as the computer is on or asleep. When the computer has been shut down correctly, LED 1 behavior may differ:

If a startup event is scheduled in System Preferences/Energy Saver, then LED 1 will stay on after a correct shutdown.

If no startup event is scheduled in System Preferences/Energy Saver, then LED 1 will turn off and will stay off as long as the power cord is kept connected and an AC power source is present. Disconnecting the power cord and plugging it back in will turn this LED back on, even if the computer is still off.

After disconnecting and reconnecting the AC power source, this LED could remain off:

If the AC power source is missing or disconnected.

If the logic board is disconnected from the power supply or the AC receptacle.

If the power supply board is faulty.

LED 2 - Indicates that the computer is turned on. This LED will be on as long as the computer is turned on (but is not asleep) and the power supply and voltage regulators are working correctly.

LED 3 - Indicates that the logic board and GPU are communicating. This LED will be on when the CPU is communicating properly with the GPU. If LEDs 1 and 2 are on and LED 3 is off, then the backup battery (on the back of the logic board) may need to be reseated or the

logic board may need replacement.

LED 4 - Indicates that the logic board and LCD panel are communicating. This LED will be on when the computer is turned on and a video signal is being generated. If LED 4 is on and there is no image on the display, then the LCD panel or the cables between the LCD and logic board might be installed incorrectly or need replacement.

LED 5 - Indicates that the logic board and LCD panel are communicating. This LED is on when the computer is turned on, a video signal is being generated, and the LCD Panel is signaling to turn on the backlight. If LED 5 is ON and there is no image on the display, then the LCD backlight or circuitry on the logic board may be malfunctioning. The LCD panel or the cables or the logic board may need replacement.

—————-

LED Startup Sequence

LED 1 = Power is available. If no LED is visible:

Disconnect the power cord from the computer and wait 15 seconds to reset the power supply and LED status.

Reconnect the power cord and check the LED status again.

Verify the AC source.

Verify that a known-good power cord is connected. Verify the cable connection between the AC inlet and the power supply.

Verify the cable connection between the power supply and the logic board.

Verify the power supply.

LED 1 + LED 2 = Power is available and the system is turned on.

If the second LED is not visible when the power button is pressed:

Verify that the power button is connected to the power supply.

Verify power button functionality.

Verify the cable connection between the power supply and the logic board.

Verify the power supply. Verify the logic board.

LED 1 + LED 2 + LED 3 = Power is available, the system is turned on, and the GPU was found.

If the third LED is not visible after the system is turned on:

Verify whether the fan is running when turned on (reset SMC

and NVRAM, verify backup battery voltage for proper startup). If the fan is not heard, go to the "No Startup" troubleshooting flow.

LED 1 + LED 2 + LED 3 + LED 4 = Power is available, the system is turned on, the logic board is communicating with the GPU, and the internal LCD was found.

If the fourth LED is not visible after the system is turned on:

Verify the embedded DisplayPort cable (eDP) connections between the LCD panel and the logic board. Inspect the LCD display cables for cable damage.

Verify external video functionality and proceed according to the result:

If an external display works, verify/replace the LCD panel. If an external display does not work, verify/replace the logic board.

LED 1 + LED 2 + LED 3 + LED 4 + LED 5 = Power is available, system is turned on, GPU is working, logic board is communicating with the LCD panel, and the LCD panel has turned on the LCD backlight.

If the fifth LED is not visible after the computer is turned on:

Verify the eDP cable and backlight cable connections between the LCD panel and the logic board.

Inspect the LCD display cables for cable damage.

Using a flashlight, check the following areas on the panel:

  1. Look in the top left corner of the panel to see if there is a dim Apple logo (the Apple menu logo).
  2. Look in the center of the panel to see if there is a login screen.
  3. Look at the bottom of the panel to see if there is a Dock visible.
  4. If the following items are visible, there maybe something wrong with the display cables or the logic board. Proceed to the next step.
  5. Replace the LCD panel, check that all the LED’s are visible, and that the backlight functions. If the computer does not function after replacing the LCD panel, replace the logic board.

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What should I do? what exactly is my situation? change power supply? I have such an article - but I can not understand my diagnosis

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If the fourth LED is not visible after the system is turned on:

Verify the embedded DisplayPort cable (eDP) connections between the LCD panel and the logic board. Inspect the LCD display cables for cable damage.

Verify external video functionality and proceed according to the result:

If an external display works, verify/replace the LCD panel. If an external display does not work, verify/replace the logic board

Do you heard tone?

Why do you open your iMac?

Do you see a backlight?

What fan go fast, in iMac you can have up to 3 fans

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no sound ! The main big fan spins slowly or in another way - very quickly! There are two options after switching on! The backlight doesn't light up! if the problem is in the motherboard - I'll hang myself in the service they asked for a lot of money and did not tell me what was the matter! they said a huge amount for repairs I want to understand exactly what is the reason

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