I have a 2009 DELL STUDIOXPS 16 laptop with most of its original parts (the HD failed and I had to change it).
Preamble: previous supply problems on this laptop
A couple of years ago, the battery stopped working properly. It only charges up to about 6%, it quickly falls to "warning, the battery is low" levels (including the white power leds by the screen hinges flashing yellow) but I still keep it mounted because it protects me from accidental power jack removal and it allows me to (quickly) move the laptop to another room.
I decided not to order a new battery because the laptop is old and it would sadden me if I had to trash it shortly after a new battery arrives.
Note that the diagnostic LEDs on the battery clearly tell me it needs replacing, so I'm sure that that problem was in the battery.
Some weeks ago, new problems started happening.
First, I had some power downs while the laptop was running and I was in another room. I got worried, but it only happened twice and then the problem vanished as mysteriously as it came.
Around a month later, I noticed that the laptop went into low battery mode while I was working on it. I quickly saved all my data and shut down the laptop before it failed. It occurred to me that this happened (several times) while I was playing a specific (recent) videogame; I lowered the game resolution and this stopped happening - the laptop is old, the game is new, maybe it's too heavy on my GPU, I thought.
A couple of weeks later, the laptop started giving me a message at startup: "unable to recognize power adapter, press F1 to continue anyway". Maybe the data pin in the middle of the jack got unsoldered? Who knows? The laptop kept working but a series of other problems quickly added up over time:
If the battery is on, there's a weird electrical noise (and the blue LED on the jack flutters like an end-of-life neon lamp) when plugging in the powered charger to the laptop. At the same time, the "low battery" yellow LED blinks. Everything goes back to normal after I get to the "press F1" screen and I actually press F1. If the battery is off, everything looks fine and I can slot the battery in later and it still works.
As soon as I plug the jack into the laptop, the jack LED dies. When removing the wall plug it stays lit for a while instead - maybe there's a capacitor in the adapter. I guess there's a thermal fuse inside the charger because the LED lights up again only if I remove the wall plug and plug it in again after a few seconds.
A co-worker checked the DC output of the adapter and it works fine (without anything connected but the tester), providing the stated voltage.
I decide to try plugging in the jack before the wall plug and it works. Sure, there's still the small noise and blinking lights, but it works.
Next day, dead again. I investigate the jack and its socket, clean the inside of the male, try to look if the pins inside the female are sticking out properly (I'm not sure they are). I also clean the vents. Anyway I manage to turn it on after several attempts. I take note of the position of the jack (even if turning the jack around after pressing F1 does not create problems).
Next time it works. Next time it doesn't work anymore. The jack LED dies even if I plug the jack in first, now. Plugging the jack first, removing the battery, then wall plugging (blinks and noise ensue until F1) seems to work pretty consistently. I can plug the battery back and it keeps working.
Now while playing a game the charger overheated and the blue LED on the jack shut off. This time I had to plug/unplug it and use my hands as a heat sink to have it work again (but the laptop didn't die on me).
What might be happening here? What am I dealing with? I'd like to repair the thing myself but I don't want to touch the wrong part.