Repair AcBel OT8043 614-0444 power supply from Apple iMac A1311

Thread Starter


Joined Aug 18, 2022
Hi all,

I've recently dismantled a friends old Apple iMac A1311 which would no longer turn on. I've removed the hard drive and got the data off.

It's an old machine now, not worth much and she's replaced it, but I wanted to try and fix it anyway. A quick removal of the power supply board showed some scorch marks underneath and black smoke stains in one corner of the device. It's not clear to me even from looking up close as to exactly which component has failed: I don't have the experience yet of knowing the failure characteristics of the various power supply components.

We're in rural New Zealand and the 230V mains power fluctuates wildly. Since moving here I've had a number of electronic items (eg: laptop chargers and other transformers) fail on me after years of faithful service elsewhere.

For those of you more experienced than I, where do you suggest that I start? I'm quite keen to start attempting to test and replace components, with some guidance.

The AcBel model number is: OT8043
The Apple part number is: 614-0444




Joined Jun 22, 2012
It's a switchmode psu, and the orange burnt object is the transformer. There will probably be Mosfets or transistors that have blown causing the burning. There are plenty for sale used on eBay...
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Thread Starter


Joined Aug 18, 2022
Thanks for helping with the correct terminology.

Yes while there aren't any replacement PSUs available for sale here in NZ I can get one shipped from China for around $65 NZD ($40 USD/EUR).

Just out of curiosity, just say I wanted to go ahead and attempt a repair on this switchmode PSU (for the process of learning - not the economics of doing so!), is it still possible to get the parts necessary to start a repair? I can anticipate your response, having seen your advice in another 'PSU repair' thread:

What you have there is a switchmode psu, unless you have the circuit diagram, or experience of repairs, you won't repair it.

Similar advice from another forum to another newbie requesting help with a PSU repair:

If you've not repaired Switch Mode Power Supplies before, it's not something I'd be attempting without a lot of assistance. These beasts can give you a hefty jolt when working, and even when unplugged for quite a while with certain kinds of faults. :eek: