Bringing a laptop back from death

My responsibilities in this job are exceptionally broad so although I’m the systems administrator with overall responsibility for the company’s IT infrastructure I’m also on occasion called upon to do things such as repair a dead laptop.

I could have delegated it to another staff member but in this case it was important that the issue should be resolved quickly. I thrive under pressure, have a real knack for troubleshooting weird computer problems and generally just enjoy getting my hands dirty when it is something that I’d never encountered before.

It was mid-afternoon when I took the call from one of our consultants that works out of the office with customers on their site and he told me that very weird things were happening with his laptop computer. It was reportedly dead, completely unresponsive and would have a strange effect on any laptop charger that was plugged into it, the LED on the charger would turn off whenever plugged into the laptop and would then not work in any other laptop until the mains power had been turned off and on.

This sounded to me like the laptop was shorting out the laptop power supplies, fortunately not permanently as it might have killed off a swath of power supplies of one of our major customers. I asked my colleague to bring it into the office so I could take a look but I wasn’t holding out much hope that it could be fixed.

I ran through some basic logical checks to see if the laptop was behaving as described and that it wasn’t something stupid like the wrong laptop charger was being used.
The charger was indeed the correct one for that model and hadn’t been swapped or mixed up with someone else’s.
Plugged it into the mains and then the laptop and the LED was the extinguished.
Did the charger work with a different laptop, yes but only after cycling the mains electricity.
Did swapping the battery help. No and the battery appeared good in another laptop.

The problem then must lie with the laptop itself and with the power input socket. If we had a spare laptop I’d have pulled the hard disk and installed it in the replacement laptop and given that to my colleague and then stuck the dead laptop on the junk pile. Unfortunately we have no spares and he needed a working laptop for Monday and couldn’t come via the office so needed me to fix then and there if possible.

No choice then but to completely dismantle the laptop so that’s what I did. About 20 screws later I finally had the case apart and I could see the wiring of the power input and theorising it was a short of some sort I examined the wiring. The wiring from the power input socket appeared to be good to me. However there was a metal bracket that kept the power input socket connected to the chassis and by removing that I could see that there was a metal contact on the socket that would then form an electrical connection to the chassis.

The chassis looked dull and therefore might be corroded and preventing the electrical contact that was required (I’d had a similar issue with the starter motor on my car last year). A bit of abrasion on the chassis at the right point to make it nice and shiny I then reassembled the power input assembly and tested it by plugging in the charger before I completely reassembled the laptop. Moment of truth. I switched the mains electricity on and the LED on the charger stayed lit so it wasn’t being shorted out by the laptop any longer. Unplugged the power. Put the laptop back together again. Plugged the power in once more and hit the on button. Lights up. Dell logo shows on screen briefly and then Windows starts its boot up.

An hour and a bit after being given a mysteriously dead laptop I gave back a working machine and all was right with the world once more.