iMac doesn’t power on, probably the power supply

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iMac Intel 20" EMC 2105 and 2118

Model A1174 with 2 GHz Core Duo or Model A1207 with 2.16 or 2.33 GHz Core 2 Duo

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visintainerelia @visintainerelia

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发帖于: 2020年2月26日

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iMac doesn’t power on, probably the power supply

When pressing the power button the Mac won’t power on.

The 3 “status led” are permanently off.

I checked the power supply, the 220/230V arrives correctly to the board but out I have like 0V and 0.5V.

I replaced one condenser which seems to be blown but nothing changed.

Do you think it could be another component of the power supply? The board looks fine

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Are you saying that the diagnostic LED are good on #1 & #2 but not #3?

由 mayer 完成的 2020年2月26日

No, 1,2,3 are off when I plug the power cable.

由 visintainerelia 完成的 2020年2月26日

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mayer @mayer

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Go for the power supply first

LED 1 - Indicates that the trickle voltage from the power supply is detected by the main logic board. This LED will remain ON while the iMac is connected to the AC power. The LED will remain on even when the computer has been shut down or put to sleep. The LED will turn off only if the AC power is disconnected or the power supply is faulty.

LED 2 - Indicates that the main logic board has detected proper power from the power supply when the computer is turned on. This LED will be ON when the computer is turned on and the power supply is working correctly.
LED 3 - Indicates that the computer and the video card are communicating. This LED will be ON when the computer is communicating properly with the video card. If LEDs 1 and 2 are ON and you heard the startup sound, but LED 3 is OFF, then the video card might be installed incorrectly or need replacement.
LED 4 - Indicates that the computer and the LCD display panel are communicating. This LED will be ON when the computer is turned on and video signal is being generated. If the LED is ON and there is no image on the LCD display panel, the LCD display panel or inverter might be installed incorrectly or need replacement.

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Yes it is the power supply for sure? But which component??

由 visintainerelia 完成的 2020年2月26日

Usually it's the capacitors. During this period there were a lot of counterfeit caps installed in lots of electronics, including Macs.

由 mayer 完成的 2020年2月26日

FYI: Capacitor plague

由 Dan 完成的 2020年2月26日

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Are you saying that the diagnostic LED are good on #1 & #2 but not #3? — mayer
Usually it's the capacitors. During this period there were a lot of counterfeit caps installed in lots of electronics, including Macs. — mayer

iMac Intel 20" EMC 2105 and 2118

iMac doesn’t power on, probably the power supply

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