Intermittent Laptop Power Prob
March 31, 2007 12:29 PM   Subscribe

OK it is well known that one of the weak links in the power system of a laptop is the AC adapter cord, BUT. . . .

A couple years ago, this slowly went out, on my Inspiron 2650. It shows up with indications that the battery does not get charged when the cord is plugged in and when the cord is jiggled, it connects, etc. Then is progressively unresponsive to cord jiggling, until ceases to charge, altogether.

So two years ago, got a new cord, problem fixed. Well it started happening again, got progressively worse, until the computer was unusable (this teamed with a worn out battery). Ordered a new cord, and now it works better but not completely. It still phases back and forth between charging and running off the battery when plugged in.

I have read that sometimes the problem is IN the computer in the connection to the motherboard, and the fix for this is a new motherboard, aka, new computer.

But on further inspection of the connection, I noticed that one of the three "male" pins on the computer side of the connection is discolored, possibly with corrosion. I am wondering if I got some contact cleaner and put it on there, if this might help the connection.

What I cannot explain is the fact that this brand new part seems to only make it a little better, but not fix, the problem. If it was the motherboard connection, it seems that a new cord would make no difference at all. If it was the cord, it seems that the new cord fixes it. My only guess left is the physical connection of the pins to the sockets inside the cord plug.

Any other guesses? Has anyone else dealt with this?
posted by Danf to Computers & Internet (6 answers total) 1 user marked this as a favorite
 
Best answer: Generally the failure point in laptop cords is that they are coaxial. Over time the outer sheath of wire gets bent this way and that and eventually starts cracking. This is usually where you get the 'wiggle the cord and it works' phenomena from.

The other thing that could be wrong could indeed be the connector in the computer having come loose from the motherboard.

Is there any you can pin the connector in the laptop in place? I'm thinking a thin gap whereby you could introduce something small, like a shim to keep the connector from having any kind of play? The less it can wiggle the less it will be able to work itself free from it's connection on the motherboard.

And this doesn't solve your problem, but one thing I've learned from having to replace many laptop cords, is that now as soon as I get a new one, I reinforce the ends with electric tape. Basically, I just make the last length (3" or so) a bit more rigid so that the outer sheath of wire doesn't get stressed in the same way.
posted by quin at 1:05 PM on March 31, 2007


...any way you can pin the connector in place...
posted by quin at 1:06 PM on March 31, 2007


FWIW, I had this same problem (3 times none the less), and since the laptop was under warranty, it fell under Dell's lemon replacement, and my 5150 was replaced with a 9400, free of charge. I simply insisted to Dell that if the same thing keeps happening, then the product itself is defective. Bam. Brand new laptop.
posted by potch at 1:10 PM on March 31, 2007


I expect the problem is a look or broken connection.

It may be worth rubbing the discolored connector with a pencil eraser.
posted by bottlebrushtree at 1:40 PM on March 31, 2007


Best answer: Don't replace the motherboard (unless you’re still under warranty). Give it someone handy and they can replace just the female socket. Or even better, as in the case of my own laptop:
Solder a cable to the old motherboard and attach the cable firmly to the case (not the motherboard) and then put the female socket on that cable instead and I'll bet it will last as long as the laptop. That way the wiggle factor will not destroy the plug or socket, since a tug will just release it. This will mean the laptop got a small “tail” though -- an endearing side effect of a near-permanent fix to a problem or a horrendous appendix, your call.
posted by JeNeSaisQuoi at 2:38 PM on March 31, 2007


My guess: the discolouration is more likely from heat or micro-arcing than corrosion (in which case cleaning/polishing in situ will probably be impossible). I'd bet either (a) the connection between pins of the female plug on the cord and male socket on the laptop are actually looser than normal (though tighter than your old faulty cord), or (b) that pin has a fractured joint (either solder or mechanical, I've seen both) where it connects to the motherboard.

If it's (a), then you may be able to crimp the connectors a bit tighter. I'm not at all familiar with the exact connector in question, though, so I'll make no suggestions as to how.

If it's (b), then there's nothing you can do short of having someone open it up and resolder the connection / replace the socket.

FWIW, being coaxial or not has nothing very little to do with laptop cords failing like this. It's mostly to do with the fact they're expected to be extremely light and extremely flexible - two contradictory aims. They're expected to put up with being flexed mostly at a single point (where the cable meets the connector or brick, regardless of any strain relief moulding) and hauled on by clotheads who pull the cable rather than the connector. You see exactly the same failure modes in coaxial power & signal cables as you do in figure-8, ribbon, and multicore cables, with about the same rates of occurrence.

What can you do to prevent cables breaking like that? Don't haul on the cable - grab the connector & pull. Don't wrap them tightly around the power brick - leave a loop where it exits the brick, then wrap them loosely. Don't let the brick hang in mid-air. Don't force the cord to make a sharp bend anywhere - exiting the brick, exiting the plug, or over the edge of the desk. Don't coil them starting at the plug end - start at the heavy end, and don't coil too tightly.
posted by Pinback at 4:22 PM on March 31, 2007


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