Dell Inspiron M5030 intermittent short

[kschaffner]

Greetings, I should state that I have been a technician for 6 years now and have a good knowledge base for repair. Onto the issue! I have a Dell Inspiron M5030 laptop that has an odd intermittent short. Some history, last week the computer would not draw power from the ac adapter (ac adapter tests fine and tried others) but would power on and run just fine from battery. I disassembled the computer and busted out the multimeter. I traced the power from the dc jack all the way through the battery circuit and pretty much the entire board and everything checked out. I unplugged the ac adapter and hooked up the battery and traced it as well nothing seemed wrong. Upon plugging the AC adapter back into the unit it began to start charging and working as it should. I assumed (bad idea, I know

) that there was just a residual charge in a chip that I cleared with the multimeter. Now 1 week later it is doing the same thing. Traced the power and voila started charging again. There is a grey chip near the DC jack that I was getting the 19.58v on one side and not the other and the chips on the other side were getting the ~12v from the battery. Upon moving my multimeter to the other side of the chip I got a small spark and then the unit started to charge again. Do you think that this is my culprit? I have posted an image to show you where the chip in question is.

http://imgur.com/GHu0d

Thanks for your time!

 

[starhawk]

Some knowledge of electronic circuitry and schematic symbols (or labels, anyhow) is handy here, although there is one thing that's throwing me off a little.

"L####" means that the component is an inductor, but I'm not sure if "PL" means something different. Probably, as there are other "P"-prefixed standard symbols there, what is going on is that they've implemented a nonstandard prefix and it is indeed an inductor of some sort.

What you're describing is more the behavior of a capacitor, though: charge and discharge. That's also puzzling me -- although inductors do have some capacitance, that's not what they're used for.

I hope I'm helping and not just being generally confusing.

 

[kschaffner]

Would a bad capacity allow the unit to run off of battery power and not switch to the DC when it is plugged in. From what I've kinda gathered at this point is that the inductor didn't seem to be passing current through it until I touched the multimeter to it. Not sure how that makes it work though. Once a connection has been established it seems to last a long time. 24 hours as of right now with no issue.

 

[starhawk]

My knowledge of circuitry is not nearly that grand; I'm honestly not sure at this point. My best recommendation is to replace the board rather than mess around with identifying and then soldering in a new SMT component -- both of which are excruciatingly difficult tasks.

TBH, if I knew that the laptop was under warranty still (check the service tag on the bottom, google will tell you where to go to type it in), I'd put it back together, call Dell, and act stupid. Unless it's obvious that you cracked the case, they should fix it for you, for free.

Your best alternative, if it's out of warranty, or if dealing with Dell is too much (I don't blame you!) is to get the part on eBay. The two part number forms I've found are:
(1) Two-digit number, then a letter, then a four-digit number. e.g. 08g8291
(2) A*DA (* usually = M or X), then a three digit number, a letter, and a second three digit number (usually, but not always, three zeros). e.g. AXDA112B000 or AMDA213B002 or even AXDA000M001.

You can easily find the part # from the serial # (DELL S/N: bunch-of-garble-separated-by-dashes) -- it's usually the second group of alphanumeric garble-soup, and it's always in form (1). Form (2) is more common for chassis parts or assemblies (like palmrest plus touchpad and buttons) than it is for the electronics.

That said, you probably know all this stuff. A year ago, I'd never even opened a laptop. Most of what I just said came from inventorying all the laptop parts I have collected since (3/4 of a 58qt. bin ) and am now trying to get rid of.

 

[kschaffner]

The laptop is out of warranty and a new board runs around $230 which is more than I'd be willing to put into it. I have a friend with an oscilloscope and is an electrical engineer that I will be bringing it to to see if he can verify my opinion on what the cause is.