Please help trooubleshooting 27" iMac power supply

[Frankentronics]

...my Mac laptop, like me, are so old we basically are still living in the past.

You're not alone. I still sometimes boot my old Mac PowerBook G4 laptop, as it has some applications that never got updated and are the only applications that can open certain files that I occasionally have to open.

To answer your question, yes I do periodically reset PRAM. I'll do it again now.

I'll look more for the service docs and I'll save the old logs.

For now the computer is working, although it is not fixed. But it takes some pressure off as we have time to think.

Again, thank you all for taking the time to help me out.

[cdev]

Computers are binary so, you're much better off with a 1 than a 0

Dust or vacuum out the inside (in a non static producing way) so it can stay cool..

[cdev]

Do you have children? If not you should turn off the parental protection.

[kripton2035]

you won't find a lot of informations in the 27" service manual except the leds meaning I gave you earlier.
these service manuals, I quite never use them. you have 5 boards in the computer, it's all simple logic to find the faulty one.

in your case, it's certainly the graphic card faulty.
there was an exchange program for these, but it is discontinued now.
we have an internal program for the apple technicians, that tells us if the graphic card is considered as defective from this exchange program.

go to an apple service center, ask them ho much they charge you for launching this program on your imac
if the program says "failed" then you can claim apple to change it free of charge.
these 2011 imacs will become vintage in the coming months (may be even in december), so don't loose time.
after that it will be impossible to change them, you will get only loosy cards from ebay, or heat the graphic chip for some months of use.

[kripton2035]

You're not alone. I still sometimes boot my old Mac PowerBook G4 laptop, as it has some applications that never got updated and are the only applications that can open certain files that I occasionally have to open.

you can use a free program called "sheepshaver" that will let you have a mac os 9 virtual machine in your actuel mac
plus if you have an ssd drive, it will be blazing fast compared to these olg powerbooks.

[a.ekholm]

I had a imac 27" which I did a reflow with a heatgun on the gpu. Worked fine. I did use a software that increased the fanspeed after wards

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[kripton2035]

how long ago did you heat your graphic card ?

[a.ekholm]

Don't remember followed a guide on YouTube. Had a ir-thermometer to monitor temp. But think it was 2minutes

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[kripton2035]

not how much time you heated the card, but when did you do it ? 6 months ago, more ?

[a.ekholm]

Sorry!
I had it a couple of months (bought it broken) and did some stress tests. And with software the temp was lowered allot. Then I sold it and bought a rigol 1054z oscilloscope for the money. So without the imac I shouldn't be here

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