Asus N71JQ no power - dodgy repair?

I've got an Asus N71JQ laptop which I bought second hand when I was in the states (think it was about 2 months old). I've used it for around a year now, and it's been totally trouble free, apart from last week when it suddenly failed to turn on.
I've tried different chargers, but still no luck - the battery doesn't even charge: nothing at all happens.
It's still covered by asus' warranty, but before I sent it off I decided to open it up and see what, if anything was causing the problem.
The first thing I noticed was the warranty sticker covering the heatsink screws had been broken, but strangely there was two rather than one, although both were damaged. Curiously, the only reason why you would undo the screws would be to access the CPU/GPU, both of which look fine. However, now I obviously can't send it back to asus. Here's a pic of what it looked like if you're interested:
http://img841.imageshack.us/img841/5608/pa200005v.jpg
I decided to check out the DC jack, as that seemed the most likely culprit as no power was getting to the laptop at all. Having taken a close look at the solder joints, I believe I may be right, but I'm not sure. To me at least it seems like it's been repaired in the past - the solder looks like it was applied by a human rather than a machine, but what do you think? Here's the pictures:
http://img163.imageshack.us/img163/4845/pa200004.jpg
http://img405.imageshack.us/img405/3157/pa200003.jpg
http://img834.imageshack.us/img834/7317/pa200002.jpg
http://img196.imageshack.us/img196/58/pa200001q.jpg
Even if that was the case, the repair looks pretty good to me. Is it possible that it's the issue anyway? Is it worth paying someone £70 to solder a new DC jack on?

TL;DR: What is causing my laptop to not get any power. If it's the DC jack, is the soldering dodgy?

Thanks

 

That is definitely what a repaired dc jack looks like.

It's possible that it was repaired by an asus repair center though. They don't usually replace warranty stickers once they open the machine.

Have you tried a new charger?

BTW, your images need to be under 500px if you want them in the post ( forum rules )... I changed them to links.

 

Sorry Many thanks for sorting it out for me.
I called asus and they confirmed that the laptop has never been in for repair, so if it has indeed been repaired, it wasn't by an asus repair centre. This is all so confusing....
As for a new charger, I've tried others of the same plug size. Although they're not strictly speaking meant for that laptop, I would have thought that they would have at least charged the battery? With every charger I tried, there wasn't a single light on the machine, and I'm reluctant to spend £25 for a new charger on a dead laptop.

 

Compare the amps and voltage rating on the adapters, if the numbers are less on the other adapter it may not work at all.

If you have a multimeter you can test both the jack and the ac adapter plug for continuity.

 

Okay, well the original one is 120W 6.3A and the ones I've tried are 90W 4.74A, so they're definitely underpowered. Even so, I'd have thought it would have done something - I could run my old Dell XPS which required a 120w charger on a 40w as long as I wasn't doing anything intensive!
As far as the multimeter goes, I do actually have one but have no clue how to use it.

 

If you have a multimeter with a continuity setting, use that. Otherwise set it to the lowest Ohm value. Touch the tip of the DC jack and then with the other probe touch one of the solder points for the posts.

I'm not sure exactly which is which on your jack but you should not see an infinite reading if it's not shorted.

My *guess* is that in this pic, the two pins at the bottom are grounds and the back two are positive and negative: http://img405.imageshack.us/img405/3157/pa200003.jpg

 

Okay, thanks once again. I'll get the multimeter out as soon as I can (probably sunday because I'm super-busy right now) and see what I get. If it reads zero, I can safely assume it needs a new DC jack right?

 

Be careful with that meter if your not sure how to use it, The internal batteries must be good to use the OHM scale as suggested. To check for DC voltage, no problem, you want to check for 19VDC on the tip of your charger plug. If this is good then check to see if you have a power LED on your brick and it is lit. If yes to both then I would then check your power jack for OHMS after you remove battery.

My gut feeling, by your post wording, is that you have a board problem. You said that "it suddenly failed to turn on". If so, NOT good. If your power brick was bad then your battery would continue to run laptop with the no AC power led lit; then eventually your laptop would shut down due to low battery. Makes sense?

BTW, yes agree, your laptop has been worked on. You can also read the 18-19VDC at the solder joint and wiggle jack to see if power makes and breaks if you cant get the ohm scale to work..good luck!

 

Thanks for that - I see what you mean and it makes sense. I'm about to break out the multimeter and will see how I get on.

 

Okay, so I tested it with a multimeter and was getting a 19v reading on the charger. When I tried plugging into the charger and testing the pins on the PCB the highest result I got was 4.5v. Does that mean there's definitely a problem? I tried pressing the power button on the laptop and there was no change in the reading. Here's the settings I used on the multimeter, I assume they're correct?

 

The one at 6 o'clock is a continuity setting (just next to 200Ohm and 8Cyl). Use that on your power jack.

 

Okay, I just tried that. The multimeter made a kind of squeaking noise as I moved the points around the solder on the jack. The reading was all over the place depending on what part of the solder I touched - anything from 400 to 1885. Does that mean there's nothing wrong with the jack, as power appears to be getting to the laptop?

 

Yeah the squeak means it's making a circuit.

Another possibility is that the jack itself is OK, but somewhere on the board there is a problem.

 

Yeah I guess there could be another issue It only squeaks when I touch certain parts of the solder.

 

When you plug in your ac adapter, does the light on it stay on? Is there any indicator LED on the laptop itself?

When your computer died, was your battery also dead?

 

The light stays on, but none of the indicator lights on the laptop come on, not even the battery charging one. To be honest, I can't remember if there was any charge in the battery when it died.

 

If you hit the power button, do you get even a flicker on any of the LEDs?

Have you tried powering it on without the battery plugged in?

 

Yes, I have tried that. I get no sign of life whatsoever from anything

 

Hrmmm..

Well if your DC jack is making a circuit, and your ac adapter isn't at fault... I'm going to guess your battery wasn't totally dead, because you would have remembered the computer powering itself off and warning you about low battery.

Normally I would say pull the CMOS battery for 10 seconds to clear the settings, but I think you should just send it in to ASUS. You should be getting *some* sign of life from the LEDs, either through the battery or through the AC adapter. If the AC adapter light isn't going off it means the DC jack isn't shorting it out.

I looked at the disassembly guide, and it would involve everything from P.9 to P.13 minus step 4 on P.13.

You can see the CMOS battery on P.19 at the very bottom, circled at the lower left.

That's an awful lot of work for a shot in the dark.

At this point I would send it in for an RMA since it's still under warranty.

 

Unfortunately it isn't still under warranty, as the sticker was damaged by the previous owner, something I only found out when I pulled the motherboard out. The laptop is now totally disassembled so I can try any form of repair, although I've already tried resetting the CMOS. By the way, the tips of the leads coming from the multimeter sparked occasionally when touching certain parts of the solder, specifically the parts on the top side of the board. Is this normal?

 

Just because warranty seals are broken doesn't mean it's not under warranty. I would try my luck in your situation. No doubt. I read a lot of experiences on these forums, and it's luck of the draw for whomever services your laptop.

Did you leave the battery plugged in when you tested the dc jack?

 

Hmm, thanks for the advice I think that's exactly what I'll do, but I'll make sure there's no other ways of sorting it out first. And no, I didn't leave the battery plugged in.

 

Since you have it totally disassembled, do you see any telltale signs of toasted components, discolored segments of the PCB, exploded caps, melted resistors, etc?

 

I've had a look over it with an ultra-bright torch and I can't see anything suspect at all. I may see if I can take some high res photos tomorrow if you'd be prepared to have a look?

 

Sure, I'll take a look. I'll subscribe to this thread so I remember to check.

 

Brilliant, thanks for all your help. If you can't see any obvious problems then I'll send it to asus and hope they don't check too closely.

 

Hi Guys I'm Alex from France and I have exactly the same problem as WoodPigeon4.
I've let my computer on and left; when I came back, there had no way to turn it on again.
I've been to a shop to make some tests and made the following tests:
*I've tested with a new charger... nothing happened
*I've tested with another battery (charged one) and the computer works
...So I've changed the Jack conector but it still doesn't charge.

If you see any solution I would be more than grateful.

I tell you if I have some news.

 

Is your computer an asus N71JQ as well?

 

Hi Woodpigeon,

Yes I indeed have the same computer as you.
The ASUS N71JQ

Tell me if you have news.

Cheers

 

I definitely will do. Do you know if the battery you used has any charge left? If so, is there any chance at all that I could try it in my laptop and see if it works like yours? It's not possible to buy batteries for my laptop in england.
Also, someone on another forum told me that I was using the wrong setting on the multimeter - I had it at 20v ac when doing the readings and needed to have it at 20v dc. When I repeated the test with DC I got a reading of 19v at the jack pins (before they connect to the motherboard) but no reading whatsoever on the solder. Did you try using a multimeter at 20v dc?

 

Unfortunately it's the guy at the shop I've been who has tested it in front of me with a brand new battery.
Just go to a shop where they sell 17,1 unches labtops and just ask to test with their battery
you have nothing to lose.
I've tried with a multimeter even at the battery pins (where the battery is plugged on the motherboard) I get 19v.

I really don't know what's going on :s

 

Okay, thanks for the info. Have you been testing it with the 20v dc setting on the multimeter?

 

Yes I have.

 

Okay, looks like you have the same problem as me: here's an update of what's happened since I last posted
Another forum member very kindly gave up his time to solder on a brand new DC jack for me. When I got home I put the laptop back together and unfortunately the problem remained. Whilst I was there, he also took a look over the board for me for any other possible suspect areas and identified a particular area near the battery charging pins as a potential problem.
I've taken some photos of it, and I would greatly appreciate any opinions on whether it's the problem or not. Higher res photos are available if required
http://img252.imageshack.us/img252/9787/pa280004w.jpg
http://img841.imageshack.us/img841/6719/pa280003.jpg
http://img526.imageshack.us/img526/1107/pa280002n.jpg
http://img714.imageshack.us/img714/8594/pa280001t.jpg

 

Hi sorry for my late answer but I was in Germany for the weekend.

I've just had a look to the pics and nothing differs from my motherboard.

I don't know if you are in the same case as me but when I plug the charger in the battery I can hear a "clic" sound and I can't find where the sound comes from :s

It could be a condensator maybe.

I've also changed the DC jack and nothing more.

We stay in touch anyways.

ALex

 

I don't hear a click sound, but if you're saying the board looks the same as mine then maybe you have the same problem as me? Either way, I've just phoned asus and they granted me an RMA (I explained that a professional had taken a look at the laptop and found issues on the circuit and I could send them photos if they required them). However, what they will say when they get it I have no idea - I'm not very hopeful of getting a replacement.

 

Hi,

I've tried again to find the cause of the problem and found nothing.
do you have some news on your side?

I'm really wondering if I shouldn't buy a new motherboard.

Cheers

Alex

 

Hey guys. Not sure if this thread is still alive but I wanted to throw my experience in there. I have also had a similar problem (same laptop). My charger port had broken about 5 or 6 months ago so I put in a new one. However I could not get the old pins to come out correctly (and also wanted the port to be away from the heat sinc anyways) so I put my new charger port on the end of some extra power cable from a broken charger I had lying around. This worked up until about a few weeks ago.

Now I am in the same position as you guys. I press power and get nothing. I have unsoldered and resoldered the charger port with no luck. I have a bit of a background in electronics so I was able to test all of the connections and have not been able to find a faulty connection either. I am probably to the point of buying a new motherboard. Any idea of what a "good" price range for one would be? I mean I can look at ebay, but if anyone knows what they should run it would be a huge help while I hunt around.