iMac 27" a1312 PS problems. Need Service Manuals

[SweetDoug]

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Came across a 27" 2011 a1312 iMac, that won't start. Opened it up and poked around, and it appears it needs a PS at first blush.

Does anyone have, or can point me to the Tech Manuals, service manuals on how to test the PS, or any tips.

I don't even know where the LEDs are!

I get power into the PS but only 25.8 volts on the 4th pin on the output, if that helps.

Anyway, any suggestions would be great.

Thanks,

SweetDoug

 

[chscag]

You may be able to find a bootleg copy of an Apple service manual. Check on eBay. I might warn you that if you do find a genuine Apple service manual for your iMac, it's probably going to be a photocopy and expensive.

Apple keeps a close hold on all their service manuals. Only genius bars and AASPs have them.

 

[pigoo3]

Anyway, any suggestions would be great.

If you were to determine that this iMac's power supply is bad...what will you do then? If you are capable of repairing the PS...great. If replacing the PS is the plan if it is bad...save yourself some time...and order a replacement now.

- Nick

 

[SweetDoug]

Repair/Replace PS

I just want to make sure it is the problem.

I can't even find the Diagnostic LEDs!

I might take it to an electronics guy I know, who could work on it.

But I'll probably just take a flyer and order one from ebay.

 

[SweetDoug]

I wonder what the reasoning is behind this?

SD

 

[chscag]

I wonder what the reasoning is behind this? SD

Reasoning behind what? If you're referring to the availability of service manuals for Macs, think proprietary, think trade secrets, think Apple. ;D

 

[jasongoldworthy]

the diagnostic leds are located on the front of the logic board once you remove the screen

 

[harryb2448]

Power Supply problems are pretty usual stuff for a 7 year old computer. Have a look at this from ifiixit.com on changing the Power Supply and familiarise yourself with the procedure. They also sell the Power Supply for $139.00. If in doubt and you are close to an Apple Store, ring and ask if they would diagnose the problem for you. Your imac is on the cusp of Apple declaring it obsolete and will not work on it at an Apple Store. A Reseller will probably charge for a diagnosis.


https://www.ifixit.com/Answers/View...nostic+LEDs+on+the+iMac+mid-2011+27"+EMC+2429


https://www.ifixit.com/Guide/iMac+Intel+27-Inch+EMC+2429+Power+Supply+Replacement/7571

 

[SweetDoug]

Yeahp, you're right.

I'm one of those open source libertarian types who likes to at least, try things on their own, maybe learn a bit.

 

[SweetDoug]

I actually used to be a mac IS guy back in the 90's, and don't mind watch a Youtube viddy and getting my hands dirty.

I've got the thing torn apart right now.

I've got power coming into/from the pigtail from the Mac into the board, but nothing on the board.

If the PS circuit board back side is facing you--solder connections on the back facing you, on the top right where the plug for the output is, top right, I'm only getting some power at 08, 25.6 volts I think.

Is this dead?



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SD

 

[SweetDoug]

I'm sitting in the dark, with the power into the mac, PS hooked up, and I can't find'em!

Any way to be more specific? I've looked for a pict somewhere, but can't find anything.

Power into the machine, blah-blah-blah… I should have the first LED somewhere.

SD

 

[harryb2448]

There is a pic in my first ifixit link.

 

[SweetDoug]

deleted

 

[SweetDoug]

This is odd.

Thanks for the links, and I found those, but here's the problem: My board doesn't have the LEDs where this picture says they are??

I have tripled check, it is the a1312 27".

Suggestions? What I think are the LEDS...


General Background Shot of the iMac



What I Think Are The LEDs


Another Shot of the LEDs


Hope this helps,

SD

 

[pm-r]

I don't know if it will help, but I found a link to the iMac (27-inch, Mid 2010) Apple Service Manual:
http://tim.id.au/laptops/apple/imac/imac_27_mid10.pdf

No sign of anything later that I could find but some other models listed in the mother directory.

Close but no cigar!!



EDIT:

iMac (21.5-inch, Mid 2011) Service Manual is here:
http://docshare01.docshare.tips/files/23542/235427388.pdf

CAUTION: Watch out for phony add-on etc. and phony Flash updater it looks like.




- Patrick
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[SweetDoug]

Good stuff pm-r!

I will peruse it and see what I can suss out. Big help in the right direction. I've located a PS close to home for about $40!

Now, if I can find a cheap hard drive caddy for the thing--Somebody thought they'd take the drive out and took the caddy with them!--I could be up and running for under a hun!

SD

 

[pm-r]

Maybe this will help for the Diagnostic LEDs:

The iMac (27-inch, Mid 2010) computer has four built-in diagnostic LEDs on the main logic board that can help you to troubleshoot the computer. The LEDs are located on the bottomleft edge of the logic board (under a piece of black mylar tape) and can only be seen whenlooking through the lower vents of the enclosure. Refer to the next page for a close up graphicof the troubleshooting LEDs.Location of Diagnostic LEDsThe LEDs are located under the mylar tape, on the bottom, left corner of the logic board. They can only be seen when looking through lower vents of rear housing:

https://www.manualslib.com/manual/624075/Apple-Imac.html#manual
https://www.manualslib.com/manual/624075/Apple-Imac.html?page=29#manual

More on the LEDs on the following pages.

Hope this helps.




- Patrick
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[pm-r]

Somebody thought they'd take the drive out and took the caddy with them!

There's always good quality HD double sided foam mounting tape you can use. :Blushing:
But a lot of SSD drives if you go that route often include a bracket if that would work by itself.



- Patrick
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[SweetDoug]

Ya ought'a be ashamed of yerselfs...

DS Tape! What's next!? Juz' duc'tape'er tagether!

My buddy who's got a mac shop said the same thing! No pride. I'd already figured it wouldn't work.

Not that a piece of 16 steel angle cleverly scissored out, with 4 holes by your's truly, isn't worth $25 on eBay!

DS

 

[pm-r]

Ya ought'a be ashamed of yerselfs...

DS Tape! What's next!? Juz' duc'tape'er tagether!

My buddy who's got a mac shop said the same thing! No pride. I'd already figured it wouldn't work

Heck, why not.

I've had Macs with their PRAM battery and drives held in with super strong velcro and gee, Apple seems content using just glue or sticky tape to hold sone of their batteries in and/or their whole products held together. ;D




- Patrick
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