Laptop's AC adapter turns off when connected, corrosion on power-related components

[fireaza]

Hi guys,

I picked up a used Alienware 15 which the seller described as not working. It didn't come with an AC adapter, so I wasn't able to get hands on with it until today. Anyway, I plugged in the AC adapter and the laptop wouldn't power on. I also tried disconnecting the battery to force the laptop to use AC power in case the battery was bad. Same problem.

I then noticed that when the AC adapter was plugged in, the LED light on it would turn off. Seems like there's a short or something that's triggering the AC adapter to cut power. I disassembled the laptop and tried connecting the AC adapter to the AC jack after disconnecting it from the motherboard. No problems, the LED stays on.

I read up on this issue a bit, and it seems like static discharges are a common problem with Dell laptops that are the cause of the AC adapter LED turning off problem. It seems there's a few components on the motherboard that can fry when this happens and to fix the problem, they need to be replaced.

And on that topic, here's a photo of the area of the motherboard, where the power components are suppose to live, see anything useful?

https://i.imgur.com/AmTBgZQ.jpg

Anyway, I had a bit of a poke around with a multi meter, testing continuity between the solder points of various components to check if they might be busted. They all seemed OK, but when I tested the MOSFET at PQ707, I was able to get continuity (in either the form of a beep or numbers appearing on the multi meter's screen) on all the legs except for the one on the bottom right (as seen in the photo above). I was unable to find continuity from this leg to any of the other legs of the chip. This MOSFET seems to get brought up a bit with Dells that have power problems, so have I found the cause of my problem?

You can also see that a number of components (and even a solder bridge) have visible corrosion. Have these parts gone bad?

Any thoughts on this problem guys?

[kodox]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

Try testing continuity to ground on PJP100 & PJP102, if there was a beep remove the solder bridges and test for continuity again on the positive side of electrolyte capacitor if there's still a beep you found the short-to-ground area on the mosfet, try removing the mosfet and test for continuity again

[fireaza]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

Thanks for you reply! Just a heads up, while I've been soldering for many years, I actually don't know a whole lot about electronics, aside from what I've picked up though experience! Sorry if I can't grasp something that's obvious to you!

OK, I probed PJP100 and PJP102 with my multi meter to ground. I am sometimes getting the VERY briefest hint of a beep when I complete the connection and I am getting a number on on the display (around 500). Any of this info helpful?

[kodox]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

OK, i think those PJP line is normal. If you have bench power supply use it to power the mainboard, set the voltage to 12v on the power supply, after plugging it to mainboard your power supply will indicate shorts and the amperage meter will jump high ignore it for now, while the amperage still indicating high (more than 3A) search using your hand for component that getting hot, that will decrease time for searching short-to-ground component. Be carefull while touching, sometime it's get extremely hot!!!!

[fireaza]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

I don't have a bench power supply unfortunately, just the AC adapter I mentioned before. Can this be used for this? The power cuts out when it's connected, so I'm guessing not...

[kodox]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

you can't use that kind of adapter because when it detect shorts on load (the mainboard) it will protect it self and that what you see on the LED as you said at first, without using bench power supply you will extend the search time searching & figuring which components is making the shorts

[fireaza]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

Damn, using a bench power supply is the best way is it? Hmmm, would something like one of these be what I need?

http://amzn.asia/d/8GadOK9
http://amzn.asia/d/4OrTRel
http://amzn.asia/d/iKvV1Wl

I have a say, I wouldn't be too keen to buy a bench power supply if it's something that I'm only going to use once... Especially if it turns out that the mainboard of this laptop is toast or something. Are my chances of getting it working good, do you think?

[mcplslg123]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

I don't have a bench power supply unfortunately, just the AC adapter I mentioned before. Can this be used for this? The power cuts out when it's connected, so I'm guessing not...

Bench psu would have helped but thats not the end of road. Model number of alienware?? Do you have schematics?? REmove PQ701 and see if there is short on mb.

Report back with your tests.

[mcplslg123]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

Remove both pq701/707 from mb and test them out of circuit.

[fireaza]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

That would be good if the bench PSU isn't necessary!

It's an Alienware 15, 2014 model (an R1 I think). Here's a link to to it's configuration on Dell's website, I used it's service tag, so it should be pretty precise, but it doesn't seem to have schematics.

https://www.dell.com/support/home/us...fds32/diagnose

OK, I'll remove the pq701/707 chips! When you say "see if there is short on mb" do you mean use a multi meter to see if there's continuity between the solder pads that the chips sat on? Sorry again for my lack of electronics knowledge!

[Mazorca]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

On a side note, are you using the correct power supply? In my view, Dell Alienware will sometimes not charge/turn on if they do not have the correct amperage. Right now I have a 17 that uses a 240W (19.5v x 12.3a). I also had a Dell AIO that needed a 150W, using a 140W or lower wouln't make it turn on. I used a power supply set to max of 10A, worked flawlessly but gave an error that the "charger" was not original.
The original for your Dell should be 180W.

[kodox]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

Bench psu would have helped but thats not the end of road. Model number of alienware?? Do you have schematics?? REmove PQ701 and see if there is short on mb.

Report back with your tests.

Agree....
There's always another path and i hope your path is not the same like what i've been through before i had bench power supply, test-remove-test-reinstal-test-remove-test-reinstal possibly shorted components one-by-one on mainboard.

But, it's your choice though...

[fireaza]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

On a side note, are you using the correct power supply? In my view, Dell Alienware will sometimes not charge/turn on if they do not have the correct amperage. Right now I have a 17 that uses a 240W (19.5v x 12.3a). I also had a Dell AIO that needed a 150W, using a 140W or lower wouln't make it turn on. I used a power supply set to max of 10A, worked flawlessly but gave an error that the "charger" was not original.
The original for your Dell should be 180W.

I *think* it's the correct one. It's a model DA180PM111, 19.5V 9.23A 180W. Everything I read indicated this was the correct AC adapter for my laptop, but can anyone confirm? I'd feel really stupid if it turns out I was using the wrong AC adapter, though I would have expected it to boot, but give me an error about the charger like you said.

Then again, maybe I am stupid, since when I Googled the part number for the AC adapter that my laptop came with (DW5G3) I was linked to this website (https://www.parts-people.com/index.p...=item&id=16691) and the sticker on this AC adapter has a plug diagram that has the positive and negative on the opposite sides to the sticker on mine!

Agree....
There's always another path and i hope your path is not the same like what i've been through before i had bench power supply, test-remove-test-reinstal-test-remove-test-reinstal possibly shorted components one-by-one on mainboard.

But, it's your choice though...

Do you think it it would be worth it? I don't mind buying one of the ones I linked to before if you think I can use it to fix this laptop (i.e nothing so far indicates that the board is toast, but rather there's one or two faulty components that's causing my problem). If it helps, here's a photo of the entire board:

https://i.imgur.com/OhSmXsF.jpg

[Mazorca]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

According to the system configuration: 450-AAGU : 電源ﾕﾆｯﾄ : Alienware 180W AC ｱﾀﾞﾌﾟﾀ
so you do have the correct one. Invest in a bench PSU, 0-30v, 0-10a is what I use. I personally use MaxPro Freeze Spray to look for shorts, but some swear by alcohol spray, heck, I used to touch board with lower lip. (Definitely NOT a recommendation.)

[kodox]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

Do you think it it would be worth it? I don't mind buying one of the ones I linked to before if you think I can use it to fix this laptop (i.e nothing so far indicates that the board is toast, but rather there's one or two faulty components that's causing my problem). If it helps, here's a photo of the entire board:

https://i.imgur.com/OhSmXsF.jpg

Can't see clear the image with heatsink installed, if you just used bench psu just to fix this mainboard from my point of view it's just a waste

You should try other method, if 19v line has a PJP try removing the solder bridges. 85% case of shorts like this caused by small capacitor or mosfet, when mosfet is the case of shorting you should consider replacing chip that controls the mosfet too

[fireaza]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

According to the system configuration: 450-AAGU : 電源ﾕﾆｯﾄ : Alienware 180W AC ｱﾀﾞﾌﾟﾀ
so you do have the correct one. Invest in a bench PSU, 0-30v, 0-10a is what I use. I personally use MaxPro Freeze Spray to look for shorts, but some swear by alcohol spray, heck, I used to touch board with lower lip. (Definitely NOT a recommendation.)

I'm not sure if you caught my edit, but it looks like the AC adapter I bought has the polarity reversed!

https://i.imgur.com/nTVkBW5.jpg
Have I found the source of my problems?

Can't see clear the image with heatsink installed, if you just used bench psu just to fix this mainboard from my point of view it's just a waste

You should try other method, if 19v line has a PJP try removing the solder bridges. 85% case of shorts like this caused by small capacitor or mosfet, when mosfet is the case of shorting you should consider replacing chip that controls the mosfet too

The two solder bridges? I should remove them and try plugging in the AC adapter again?

[kodox]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

The two solder bridges? I should remove them and try plugging in the AC adapter again?

Yes, the solder bridges. But you shouldn't plug the AC adapter, test using the continuity again

[fireaza]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

Before I start de-soldering things, I'd like to confirm I'm actually using the right AC adapter. As I said before, it looks like the AC adapter I've used has the opposite polarity from the AC adapter intended for my laptop (model DW5G3), based on a photo of said AC adapter. If I have used an AC adapter with the wrong polarity, does that help clarify the cause of the issue I'm having with this laptop?

[mcplslg123]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

Agree....
There's always another path and i hope your path is not the same like what i've been through before i had bench power supply, test-remove-test-reinstal-test-remove-test-reinstal possibly shorted components one-by-one on mainboard.

But, it's your choice though...

Kodox, I do use a bench power supply but what i meant is not having one is not the end of road. This guy has already said so-he dont want to invest in it for just one off case. Thats why i said so.

Lets not bother much about the adapter polarity now, we can check that later before applying power again. First, we need to clear the mb of shorts. So lets focus on that. Have you removed the two fets and tested them??

[fireaza]

Re: Laptop's AC adapter turns off when connected, corrosion on power-related componen

No, not yet. I was thinking that if I used the wrong polarity AC adapter that I might have blown a fuse or something, which might have been the cause of my problems the whole time. In that case, it seemed pretty crazy to be de-soldering components if all it needed was a fuse to be replaced.

But if you're saying that I should be continuing the search for faulty components, then I'm going to take you at your word and assume that this is still the correct choice!