iMac Black Screen No Chime Led 1 Fans Rev

Question

iMac Intel 21.5" EMC 2428

Model A1311 / Mid 2011 / 2.5 & 2.7 GHz Core i5 or 2.8 GHz Core i7 Processor

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tomytom @tomytom

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crwdns2931729:0crwdne2931729:0: Nhl 9, 2022

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iMac Black Screen No Chime Led 1 Fans Rev

Hi There.

I have a problem a back screen issue.

The fans turns on with the hdd and DVD drive.

I checked the onboard diagnostics and LED 2, 3 and 4 are off.

I have replaced the PSU but but still a black screen.

I have replaced the cmos battery but still black screen.

I have baked the gpu but still black screen.

Ask for any info about Imac.

Edit.

I forgot to mention I plugged in a different keyboard when it was working and when 15 min past it crashed and I could turn it on but it would crash less then 10 min in it would crash. The next day it would not turn on I have the issue now.

@danj

This is the gpu

The specs

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score 4 · Answer 1 · 2022-10-09T22:42:59-07:00

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Ben Capehart @beanman56

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crwdns2931729:0crwdne2931729:0: Nhl 9, 2022

crwdns2933897:0crwdne2933897:0

Sounds to me Like A Scary failed logic Board Or CPU!

Take it The board out and look for any corrosion,
And Check The CPU

Guide: iMac Intel 21.5" EMC 2428 Logic Board Replacement iMac Intel 21.5" EMC 2428 CPU Replacement

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iMac Intel 21.5" EMC 2428 CPU Replacement

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3 - 5 hours

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iMac Intel 21.5" EMC 2428 Logic Board Replacement

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1 - 4 hours

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I forgot to mention I plugged in a different keyboard when it was working and when 15 min past it crashed and I could turn it on but it would crash less then 10 min in it would crash. The next day it would not turn on I have the issue now.

crwdns2934271:0Nhl 10, 2022crwdnd2934271:0 tomytom crwdne2934271:0

Hmm... I'd say try reseating the CPU.

crwdns2934271:0Nhl 10, 2022crwdnd2934271:0 Ben Capehart crwdne2934271:0

@beanman56

It didn't work I reseated the CPU. Still doesn't work.

crwdns2934271:0Nhl 13, 2022crwdnd2934271:0 tomytom crwdne2934271:0

@tomytom - Okay sounds like a faulty logic board then...

@oldturkey03 - Any thoughts?

crwdns2934271:0Nhl 13, 2022crwdnd2934271:0 Ben Capehart crwdne2934271:0

@beanman56 - Often I find the GPU power rail is shorted to ground. Inferring a short with in the GPU board likely a burnt cap.

crwdns2934271:0Nhl 14, 2022crwdnd2934271:0 Dan crwdne2934271:0

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iMac Intel 21.5" EMC 2428

iMac Black Screen No Chime Led 1 Fans Rev

Update (01/08/2023)

Update (01/08/2023)

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iMac Intel 21.5" EMC 2428 CPU Replacement

iMac Intel 21.5" EMC 2428 Logic Board Replacement

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