Recliners are like big scissors you sit on

January 15, 2009 10:43 AM

My recliner sheared through the magsafe power cord attached to my Macbook. Is it safe to attempt to repair it? If so, what do I need and how should I go about making a clean repair?

Just to be specific, it's a fairly clean cut in the cord about 2 feet from where the magsafe connector plugs into the computer (1st gen vanilla macbook). So there's plenty of wire to work with and I'm willing to pick up a few things from Radio Shack if they'll help make a nice job of the repair.

I'm quite gentle with the cord when my sofa recliner isn't hungry, so it doesn't need to bear weight after the repair – just not melt or spark.

DIY salvage or drop $60 on a replacement?

posted by cowbellemoo to computers & internet (20 answers total)

Do you have a soldering iron and know how to solder? If so, it's a pretty easy repair. Get some white heat shrink tubing to cover it up and it will look pretty good, if not perfect. If you don't know how to solder easiest thing is to find a buddy that does and have him (or her!) walk you through it.
posted by 6550 at 10:55 AM on January 15, 2009

Looks possible. All my info on what's in the cable comes from this mod info, so who knows if it applies to your cable.

What I would do:

1) Strip 2-3" of sheathing from both sides. Pull back the ground/shield wrapping on one side and cut it shorter than the inner wire; do the reverse on the other side. You should have two ends of the cable that now look like:

XXXXX          XXXXXXXXXX
----------          -----

(X = braided sheathing, --- = inner conductor)

2) Slip heat shrink tubing over one inner conductor, and another piece over one side of the entire Magsafe cable.

3) Strip the inner conductor, lay the two ends parallel to each other, solder together. Gather the braid into two "wires" and do the same. The idea of the staggered lengths above is that your splices shouldn't be directly on top of each other. Careful not to shrink the heat-shrink tubing prematurely w/ the soldering iron.

4) Slide the inner heat shrink over that splice & apply heat; slide larger tubing over the whole shebang and heat that.

5) You're done.

I'd keep an eye out for excess heat when you start using it (my guess is that these cables are just barely rated for the current they carry, so your first warning of a bad splice may come in the way of melting sheathing). You'll need to be careful not to bend the cable where the splices are, as the solder joints present a good hard edge to fatigue & break the wire over. I might glob on a pile of hot glue to make a half-assed strain relief over the spliced section (make a football of hot glue, thick where the splices are and tapered to the undamaged section of the cable).
posted by range at 11:06 AM on January 15, 2009

Previously
posted by Xurando at 11:06 AM on January 15, 2009

One of my lovely dogs chewed up mine. I couldn't find the magsafe end immediately so I ended up buying another power supply.

If you have a soldering iron, solder, heatshrink, a reasonably decent wire stripping tool, and the experience, it's a 20 minute job. If you need to buy those things, you're going to be pretty close to $60.

That said, the wires are individually colored. Strip back the outer sheath about 1" on each side. On the longer side, slide a 3" piece of heatshrink tubing on the wire. Strip each individual wire, exposing about 1/4" to 3/8" of bare wire. For each wire, slip on an appropriately sized piece of heatshrink, then twist the wires together and solder. Fold the wire over, slide the heatshrink up, and shrink it (I use a lighter). Once you have all four (I think) wires connected, slide your outer cover up and shrink it.
posted by jdfan at 11:10 AM on January 15, 2009

I don't have soldering experience, but I think this is a fine time to learn. Unfortunately, I'm king nerd around here and don't have a buddy to walk me through it. I'm not pressed for time and I'm willing to spend money on equipment I can use with confidence down the road – so I'll watch some solder how-to videos and get to it at my leisure.

xurando: oops! I'm usually pretty good trying to find dupes first, but this time I only did a few google searches with poor results. Sorry for that.

Thanks all. Seems like a pretty standard splice if jdfan and range are describing essentially the same procedure. It doesn't look so scary now.
posted by cowbellemoo at 11:49 AM on January 15, 2009

If you have AppleCare, and you're friendly when you call, they may actually replace it free of charge. No guarantees though, since AppleCare pretty explicitly doesn't cover accidental damage.
posted by Asymptote at 11:50 AM on January 15, 2009

If you are going to solder it (it really isn't necessary as a good twisting should suffice) get one of those little third hand jigs with some clips which hold the work leaving your hands free to hold the soldering iron and the solder. Remember to heat the wire with the iron and then apply the solder to the heated wire not to the iron. A tiny drop of solder on the iron before you touch the wire will speed heat transfer to the wire. Of course you will practice on some scrap before soldering your Apple wires. Soldering wire is really, really easy so this should work out great for you.
posted by caddis at 12:05 PM on January 15, 2009

I've done this twice with the double-heatshrink technique range described, and I regrettably have to tell you that it was just a matter of time before both repairs broke when the cord was bent near the join, because it's a much more brittle connection than the original flexible cable, the cabling is thin and therefore so is the solder connection, and any bending travels up and down the cord to a certain extent. It was a free (re-)fix for me because I already have the equipment, but it's tedious and then only semi-reliable after the fact. I think it would be a good approach with a more robust form of strain relief, but I don't know the best practices in that area.
posted by Your Time Machine Sucks at 12:18 PM on January 15, 2009

Yeah, twisting might (ironically) hold up better because you aren't solely relying on the brittle solder joint, and you can use the heatshrink to keep the twist in place.
posted by Your Time Machine Sucks at 12:20 PM on January 15, 2009

I see the drawback, but now I have a hankering to do a nice solder job. I think I'll just make a loop in the cord after soldering and ziptie the ends tight so the brittle part can just hang off to the side. Think that's acceptable?
posted by cowbellemoo at 12:44 PM on January 15, 2009

Yeah, I'm guessing some version of strain relief is going to be needed. You can do the hot glue blob I described above, or alternatively try to make the same shape by wrapping electrical tape thickly around the joint and then tapering to the sides (might as well use it for something, it's pretty useless for actually insulating wires after all).

You're trying to keep the bend radius large. What happens is that the wire will form a sharp L right at the solder joint (because the wire's flexible and the joint is stiff), which fatigues the wire right at the corner, at the edge of the joint. If you can coerce it into bending more like a C, the fatigue goes way down and you don't have as much risk. If you look at every electric cord you've ever used, you'll see something like this molded into the plug to accomplish the same thing.

If you want this as a good excuse to buy a tool, I'd recommend a Weller WLC100 -- it's by far the cheapest decent soldering iron around (I buy about 30-50/year for a couple of labs I teach in). For lead soldering, set the knob a touch above 3 and don't mess with it. Good technique and clean tips work a lot better than high heat.
posted by range at 1:14 PM on January 15, 2009

Oh right, one more thing -- the trouble with twisting the wires together is that with these current levels, you'll need to worry about making a gas-tight joint to prevent oxidation, and a joint that tight is going to create virtually the same kind of stress concentration (and risk of fatigue & breaking) as a solder splice anyway.
posted by range at 1:17 PM on January 15, 2009

Double up on the heatshrink. It'll make the whole section stiffer. Flex is the enemy of solder joints. If you can reduce the opportunity for flex, you'll reduce the chance it'll fail again.

I wouldn't recommend just twisting the wires together in this case. The additional mechanical strength of the solder trumps the potential for breakdown. Just treat it carefully.
posted by jdfan at 1:24 PM on January 15, 2009

What range said.
posted by jdfan at 1:25 PM on January 15, 2009

range (and jdfan): thanks very much for talking it through, I'm also going to give mine another shot according to your suggestions.
posted by Your Time Machine Sucks at 1:56 PM on January 15, 2009

Uh, you may burn your house down if you don't do it right. Not a good way to learn soldering.
posted by Happy Dave at 2:00 PM on January 15, 2009

Burn your house down? I doubt it, as long as the soldering iron is turned off after use. ;)

It would be hard to screw this up and anyway this part of the cord has low voltage DC. People have put their tongues on the connectors.
posted by caddis at 2:12 PM on January 15, 2009

caddis, brand new magsafe connectors have melted, a hand-fix cable that gets lots of flex definitely has potential for fire issues.
posted by nomisxid at 2:35 PM on January 15, 2009

I don't know about the repair, but if you do, move the cord away from the recliner! My boyfriend had a similar situation, only the cord wasn't cut all the way through. Instead, the metal in the recliner touched both the power and ground wires on the cable, and all of a sudden it looked like a Fourth of July fireworks show under his ass. Luckily, he walked away unscathed, but if fireworks are illegal where you are, just remember, you can always use a power adapter instead.
posted by hatsforbats at 3:04 PM on January 15, 2009

Kinda tangent to the topic here, but I just picked up a pretty spiffy cordless soldering iron at the blue-themed big box store. it's a weller, and it was like $12.

haven't used it yet, but it seems more convenient than the standard 23watt corded one. if it gets hot enough, anyway.

hopefully it's as good as the isotip i remember from college/radio days.
posted by KenManiac at 5:24 PM on January 15, 2009