Dell XPS 12 charging problem

[dakeeper]

I have a problem with my xps 12 ultrabook.

One week ago my computer was charging like normal, when I unplugged and shut the screen (sleep) and went back to my room to study some more. After an hour, I plugged in my charger and it wasn't working.

My charger has an led indicator right at the head, where it connects to the port. The led light was on, but I checked the voltage anyways and it was correct (outside/pin are 0/ground, inside is ~19.8v)

I managed to check the bios before my battery completely died, and with my ac adapter plugged in the bios indicated that it wasn't detecting an ac adapter (AD ADAPTER: NONE)

Naturally, I thought this was a dc port problem so I ordered a new one and even with the new one, it won't charge. My battery is completely dead at this point.

That's a good summary of what happened. If it's not an issue with the dc port or charger, and my bios doesn't detect the ac adapter, then it might be a motherboard problem and I don't even want to think about that. It seems as if everything points in that direction.

Upon further inspection, it seems like the charging ports aren't 100% the same, so here they are side by side:
http/m.imgur.com/uD7RuST
The top one is the one I ordered, the bottom is original. I can't seem to find any information as to the internal structure of the ports, so it may still be a dc port problem.

Later on I'm going to test to see if the DC ports are the same (voltage), try a CMOS reset by pressing the power switch for 15 seconds (or so I was told), and see if I can try out a different charger at the laptop distributor.

So my questions are, what does the bios indication of no ac adapter detected mean? Is it possible that it's a battery problem, not a motherboard problem? What other options do I have at this point?

 

[SchizTech]

Dell laptops are particular in this way: the adapter has a middle pin which is used as a power adapter ID signal. Only a Dell charger is recognized and charges the battery, where that middle pin is used to identify the charger. There is a possibility the charger isn't sending the proper signal anymore, or it's possible the motherboard isn't reading the signal. If the system runs off the charger but just doesn't charge the battery, that isn't a problem with the jack itself. Some Dell models have a separate power board which can be replaced independently of the main board (I'm not sure how that particular model is built).

 

[dakeeper]

Plugging in the adapter without/with a battery doesn't work. Sorry, that was probably an important piece of information I've omitted.

 

[SchizTech]

Ah, I see. So the laptop only ran from the battery (until it died), the charger has power but the laptop won't run from it and replacing the jack didn't help? If I have all that correct my suspicions immediately turn to the board I'm afraid.

 

[dakeeper]

It is possible that a malfunctioning pin on the charger causes the motherboard to not detect the charger at all? That, and finding something screwy with my DC ports are the only hopes I've got.

 

[SchizTech]

Well there are only three functional areas of the charger tip: the outer surface of the barrel conveys the ground signal, the inner surface the +19.8V signal and the center pin carries an identification signal. Since you seem to have a meter (having used it to measure the power from the adapter tip) you can use it to measure power at points on the board. First, verify power coming out of the DC jack: there are solder points where the jack is connected, and you should measure the same 19.8V that the charger provides when you find the right combination of pins. If there's power there but the board won't start, that's a bad omen (no power there would indicate a bad jack).

The next step would be exposed circuits on the board. If there's no significant current anywhere else on the board, there's a power issue on the board which results in a failure to deliver power to the chips that run the system. Replacing the board is the only repair option then.

 

[dakeeper]

Okay, well that was a hectic week, but heres an update

Both the DC ports have the same output, so I'm returning one of them. I went to a distributor and checked one of the chargers, that didn't work.

Figure 1: http/i.imgur.com/xNCIcSg.png

The measurements for the output for the DC port interface to the motherboard is something like ~88 mv, 19.8v, 19.8v, 0v, and 0v. These voltages are whats coming out of the black portion that the red arrow is pointing to.

The measurements for the soldered connections from the jack to the motherboard (silver in picture) is something like .8mv, 19.8v, 19.8v, 0v, and 0v.

So, is the jack supposed to modulate the input in any way, or is the problem not there?

Also, I tried to measure some voltage drops across the motherboard but I didn't get anything conclusive. I'll check it again if the above is supposed to happen.

 

[SchizTech]

The jack isn't meant to modify the current in any way (the observed voltages are normal, and it seems like the board is getting power, but not starting). With that result it sounds like you have a bad motherboard.

 

[Devon_1]

Did you ever figure this out? I'm having a similar issue. When I plug my cord in, I can actually hear a static sound, but the computer won't turn on (the battery is dead). The indicator light on the adapter is on, so the cord is getting power, but for some reason it isn't going to the computer. That, or I have a bigger issue to deal with.

 

[Daniel_127]

I ran into exactly the same problem as dakeeper:
- Laptop wasn't charging
- Power Adapter was okay: Indicator LED was on and the Voltage was fine.

My solution was to disconent the Poweradapter and the Battery cable then to startup the Laptop to drain the remaning power in the system. It worked fine, after pluging the Battery cable back, the charging worked without a problem.

 

[Jay_68]

I myself was having the same issue. My husband bought this for me as a birthday present 3-13-13. Didn't even last 5 years. After reading your post I then remembered several times in the past on the bottom screen it would say something like this "doesn't recognize power port" or "need to plug in your power thing" somewhere on that line. Just the other day I plugged it in when battery got low and it wouldn't charge. We don't have kids around and its only me that uses it so I know that it hasn't been damaged because of rough people using it. I babied it if anything. But just called dell to tell them because I was hoping there would be some kind of warranty on it but he said no and that its the mother board and its going to cost $200.69 to fix it. I would recommend any one thinking about buying this brand to "stay away" this isn't the first of my problems w/this. It also says "connection limited" I told this to the man when I was on the phone and he said you should have said something sooner" I was so upset I just hung up and told him I wouldn't put any more money into that piece of junk.... P.S. I did get a new power adapter and still the same problem so that's how I ruled the adapter out before calling dell with the issue.

 

[mf]

I had the same problem with Dell XPS 12, it was powering the laptop but not charging the battery, "Connected but not charging" and a message showing that the laptop could not identify the adapter. I thought it was Bios or the battery has run out of life, tried most of the searched solutions on Dell community and general. Changing the adapter resolved it.