Jon Ridley

The symptoms you’ve mentioned are a-typical of the common graphics fault on the 27” 2011 iMac ranges unfortunately. The cause of the common fault on this range is related to the GPU, which is removable on this range. Basically, they used lead free solder for the GPU that made it more environmentally friendly, but with the casing design on these machines holding in so much heat, and the lower melting point of lead free solder, the GPU joints would fracture. The main reason it sounds like its the common problem is because it starts out intermittent, and is most affected when the machine is hot. So the multiple reboots would function the same as leaving it to cool for a while before re-trying. The only other possible cause is LCD panel or logic, but GPU is most likely. You noted having tried a replacement GPU already, but was it a re-balled card, or one with the original lead free solder? as you cannot buy these cards ‘new’, it is likely second hand, and very likely suffering from the same fault. we only ever...

They dont often fail, but here is the AC Mains Input Socket and Filter https://www.thebookyard.com/product.php?...

How frustrating! we’ve seen this a number of times on earlier ranges, but not on this range yet. It is classed as a ‘bonded’ unit, but in reality, the glass surface is bonded to the LCD panel around the edges, but the backlight diffuser sheets are not ‘sealed’ or ‘bonded’. So you can strip it down from behind. (It does frustrate me the way ASP and AASP providers push the ‘bonded’ excuse for dust and marks stating its ‘impossible’, but its just not the case) But in truth, without a clean room environment, you’d risk leaving a lot more behind than just a small bug, as when you open the layers it is much more susceptible to dust and dark patches. We’ve done it before, but its not a fun process… I’d suggest trying to lightly tap the glass to see if it will drop down, as it is likely touching either the glass or LCD surface. Hopefully it will drop out of the viewable area to the edge of the panel.

Hold the power button on the keyboard for 10 seconds when its turned off. you’ll find when you first turn it on the LED flashes slowly. thats searching for current connections. When you hold it longer you’ll see a rapid flash sequence (then release the button) and it will be in active ‘search’ mode. It’ll then pop up as a new device to be connected.

visually in photos, its hard to tell. But the following physical tests can be done: (1) Check EEE codes (serial numbers on Apple’s GSX database). (2) Check if duck head alignment peg is metal or plastic (it should be grounded, so needs to be metal). (3) Check LED delay when plugged in. (the IC should check if charger is genuine when first plugged into a Mac. if the LED isn’t delayed by a second before it goes green, its not got the correct IC chip). (4) Check IC chip ID and serial number (in system information panel of Mac). (5) Check power output and curve with an oscilloscope. (compare with Apple original, as we do. cheap ones will fluctuate a lot and will have a lot of ‘noise’) (6) Crack open the charger (or a few from a batch if ordering in bulk) and inspect build quality, and look for properly grounding. Obviously these tests are not all viable for an individual consumer buying a single charger, although you could do a few of the basic checks. This is the sort of testing that is required of a supplier...

without a thunderbolt controller, it wont work with Mini DisplayPort unfortunately. There is an older version of the 27” display that came with Mini DisplayPort, but they are different to the thunderbolt model

we find that most cases you can clean it from the outside by rolling the ball with a cleaning substance. But while doing this cleaning method does pull out some dirt that stops the ball mechanisms from rolling (there are 4 directional pins inside), the pins eventually get too clogged up to roll. The only way of fixing it after that is to open it and clean it from the inside. it can be done, but will require cracking the lower frame off the mouse, then re-glueing it afterwards

The LCDs are quite common to fail on these unfortunately, so it’s likely the LCD controller board. In cases where we have the same symptoms, we’ve found it to either be main logic board or LCD panel.

were the wrong size batteries fitted at a previous date? or did a battery leak in the battery compartment? it sounds like the metal spring at the bottom of the compartment isn’t making good contact with the battery, so it may be corroded or flattened too much. You can remove the inner frame on these to inspect and clean the contacts, but it’ll likely be one of those two scenarios. I hope this helps

sounds like you might have a faulty battery. Best app you can use to get a reading of the battery health is ‘Coconut Battery’ get a screen grab of the test screen on that app, then email them direct. I’ve seen quite a few replacement (non-apple) batteries have issues like this, and it is nearly always a fault with the battery. In some cases, the battery shows a full charge capacity of over 60,000 (which is physically impossible), and it powers off after a few minutes on without mains plugged in. OWC batteries have this issue from what i’ve seen, as we sell a lot of them.

No, but you do have to remove the airport/bluetooth antenna, which is held in with 0.8mm pentalobe screws.

So, disable auto boot on logic board (through terminal command)

Then remove bottom case

Then disconnect battery

Then remove antenna

Then remove display.

Make sure the display cables fold the correct way, as they are extremely delicate. I’ve seen people break them by twisting or pulling too hard

The 2 clips in the lower side of the photo are broken from being removed. The pick was shoved in too hard and damaged them more than likely.

This may prove helpful. It takes a gentle touch, not shoving the pick in through the side.

This applies for all butterfly clip types. So 2016 and 2017 MacBook Pro ranges, and 12” MacBook ranges from 2015-2016

https://thebookyard.wordpress.com/2018/0...

The 2 clips in the lower side of the photo are broken from being removed. The pick was shoved in too hard and damaged them more than likely.

This may prove helpful. It takes a gentle touch, not shoving the pick in through the side.

https://thebookyard.wordpress.com/2018/0...

I wouldn't recommend using HDDFanControl, because its not really a long term fix... I used it for a while, but it frustrated me that the fans didn't idle until the machine was fully booted, so if you need to do anything in single user mode, safe mode or even a boot camp or separate OSX boot up, you cannot use it. In the 2011 range, i'd recommend using this as a long term hardware solution

http://www.thebookyard.com/product.php?p...

Why has double sided tape been used in this guide instead of the SSD brackets that are designed to be screw mounted under the optical drive? there are 3 screw mounts allocated to the mounting of the SSD. With the heat that is generated by the iMac machines, i'd be worried about it losing its bond and falling down, especially using tape bought from Boots instead of high strength industrial tape...