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Repair guides and support for 21.5" Intel iMacs by Apple.

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Is there an internal fuse in the iMac?

My mac quit working (it won't turn on) after the power in our house flickered the other day. Is there an internal fuse that might have tripped or should I check the power supply module?

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Yep. No power getting to the computer. The outlet is okay, so I am going to assume I have a faulty power module. Hopefully nothing else. Thanks.

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There is a T6.3A 250v fuse on euro imacs in a black casing , (the PSU's look universal) . you can trace it from the power input lines it's the first component in line.

the tel tale sign it blew for me was no arcing plugging in a live power cable to the mac. also if you have it open as pointed out elsewhere no LEDs lit up on the mother board.

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I would add if his blows there is likely an issue with the PSU

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Chosen Solution

SMC RESET

Shut down the computer.

Unplug the computer's power cord from both the wall and computer.

Wait 15 seconds.

Attach the computers power cable.

Wait another 5 seconds and press the power button to turn on the computer.

UPDATE

The LED's are on the logic board to the right of the RAM slots and between the RAM slot and the HDD sata connector

LED #1

Indicates that the trickle voltage from the power supply has been detected by the main logic board. This LED will remain ON whenever the iMac is connected to a working AC power source. 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 source 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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Already did that. Several times. I even let it sit overnight unplugged and then tried again. no luck.

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That part worked. I have 2 mac Minis on a KVM. #1 works, but #2 is the problem. The arrow cursor freezes on #2, but there is no problem with on #1. I get a blue screen. I’d like to have itr running, because when I went from 10.6.8 to 10.7.5 on #1, there was software that can’t be used. This box was refurbished and tested, but you never know what you’re going to get with a rebuilt. Will it last years or 15 minutes? I shut down and zapped the P ram on startup to no avail. C’esspool la vie.

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