Repairing a Macbook Charger… With a Pistachio Nut

Laptop chargers face a hard life. They’re repeatedly plugged and unplugged, coiled up, stuffed into bags, thrown around, and just generally treated fairly poorly. Combine this with fairly lightweight design and it’s not uncommon for a laptop charger to fail after a few years. It’s usually the connector that goes first. Such was the case when I found myself face to face with a failed Macbook charger, and figured it’d be a simple fix. Alas, I was wrong.

Unlike most PC manufacturers, who rely on the humble barrel jack and its readily available variants, Apple liked to use the Magsafe connector on its Macbook line. This connector has many benefits, such as quick release in the event someone trips over the cable, and the fact that it can be plugged in without regard to orientation. However, it’s not the easiest to fix. When the charger began failing, I noticed two symptoms. The first was that the charger would only function if the cable was held just so, in exactly the right orientation. The other, was that even when it would charge, the connector would become very hot. This led me to suspect an intermittent connection was the culprit, and it was quite a poor one at that; the high resistance leading to the heat issue.

Charger cable worn out near connector
Cutting magsafe enclosure with side cutters

It’s at this point with any other charger that you get out your trusty sidecutters, lop the end off, and tap away at Digikey to get a replacement part on the way. With Magsafe? No dice. Replacement parts simply aren’t available — a common problem with proprietary connectors. I endeavoured to fix the problem anyway. I began to strip away the metal shell around the back of the connector with my sidecutters, and eventually an angle grinder. A Dremel would have been the perfect tool for the job, actually, but I persevered regardless. After much consternation, I had the connector peeled back and was able to identify the problem.

The cable of the Macbook charger consisted of a centre conductor sheathed in Teflon, which was then surrounded by two layers of shield wound in opposite directions. The center conductor is soldered to one tab which connects to the V+ pins of the Magsafe connector, and the shield connected to the other tab, leading to GND. The issue was that after many years of use, the continual flexing of the cable had caused the shielding strands to break over time, eventually making poor or no contact. This explained the symptoms we were seeing, so I was confident that I’d found the root cause. After cleaning up the solder tabs of the connector, I freshly stripped the charger wiring and soldered everything back into place. A few checks with the multimeter against the pinout indicated everything was connected correctly, and plugging the charger back into the Macbook indicated the repair was successful.

Aw, Nuts!

Filling the shell with epoxy is a delicate process. Be sure to avoid getting any glue on the spring contacts; this is an easy way to ruin the connector permanently.

There was now just one small problem to fix. While the charger was functional, it was difficult to insert and remove since the aluminium casing had been removed. This, combined with the now-exposed wires, meant something had to be done. I decided to fashion a new protective cover for the connector, and as luck would have it, I had the perfect parts to hand.

Have you ever tried to open a pistachio nut that isn’t yawning open along the seams? It impossible for mere mortals to do without tools. A pistachio shell would serve quite well as the protective outer case for the connector. The Magsafe was placed inside and the shell was filled with epoxy to hold everything together and insulate the wires.

It was difficult to hold the connector in position within the shell; if I were to attack this problem again, I’d have tacked the connector in place with superglue before filling the shell with epoxy. Regardless, I persisted. After a longer wait then expected due to the fact I’d accidentally purchased the 24-hour, not 5 minute, epoxy, it was cured.  A quick tidy up with a file and all was good to go.

I was glad to have the charger repaired. The pistachio nut encasement proved to be a worthwhile solution, giving the connector much needed robustness after being stripped down and rebuilt. It gets the odd stare here and there, because at the end of the day, there’s a pistachio sticking out of the charge port.

Is it perfect? No. Does it work? Yes.

But hey, sometimes that’s the price you pay for progress.

Fundamentally, working with proprietary connectors can be a real pain. They’re hard to source, and can completely disable a piece of equipment if they can’t be repaired. However, with a little perseverance and creativity, it is sometimes possible to save the day, if you’ve got the nuts to try.

Filed under: Hackaday Columns, Repair Hacks, Skills

Lewin Day
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