I’ve got a 21.5-inch Mid 2011 Apple iMac here for a hard drive replacement, so I thought I’d record the process while I’m at it. This particular job is being done for a charity, and it’s a good opportunity to show what goes on inside one of these machines.

I’m replacing the original 3.5-inch Seagate hard drive with a smaller 2.5-inch drive fitted into an Icy Dock adapter. I’ve also got an OWC temperature-sensor cable, which is rather important on these iMacs unless you particularly enjoy listening to the fans running at full speed.

The glass front panel is held in place magnetically, so a suction cup makes getting it off considerably easier. Behind that is the LCD itself, secured with a collection of Torx screws. Naturally, the magnets are more than happy to grab hold of those screws while you’re trying to remove them.

These machines also have an exposed power supply inside, so this isn’t something to tackle casually. Even with the iMac unplugged, stored electrical charge is a concern, and the display connections are particularly easy to damage if you’re not careful. I’ve seen some rather unfortunate results from people attempting these repairs!

With the LCD carefully moved out of the way and its cables disconnected, we can finally see the original hard drive. It’s mounted towards the middle of the machine, with a bracket holding everything in place. Getting the old drive out is actually one of the less troublesome parts of the whole adventure.

The replacement drive goes into the Icy Dock adapter, and then it’s a matter of getting the mounting hardware arranged correctly. Sounds simple enough! Unfortunately, I managed to put the bracket on the wrong way around and had to redo things. More than once, naturally.

There’s also the temperature sensor to fit and route neatly inside the case. After a bit of fiddling, I found somewhere suitable for it, although the cables and brackets seemed determined to make this take longer than necessary.

Once that’s done, the LCD can go back into position and the various display connections can be reattached. A little care is needed around the lower edge of the screen, since there are fans and other bits tucked away inside that don’t particularly appreciate being squashed.

Finally, the screws go back in and the magnetic glass panel snaps into place. Lovely! Of course, there’s still the software side to deal with, whether that’s installing an operating system or transferring an existing installation using something like Carbon Copy Cloner.

So that’s the physical hard drive replacement completed. It took a bit of mucking around, particularly with that drive bracket, but it’s all back together. Now, where did that screwdriver go?