HomeLet’s say your laptop does not start at all. You plug in the power adapter and press on the power button, but the laptop will not react. It’s dead and the power or battery charge LED will not light up.
What could be wrong? Is it bad power jack or the motherboard is dead?
By the way, the power jack aka DC-IN jack is the power socket on the side or back of your laptop where you plug the AC/DC power adapter.
I’ll explain how to perform basic troubleshooting and find out what is wrong. This is only for experienced people, who know how to disassemble laptops.
First of all, test the AC/DC power adapter with a multimeter. It’s very likely that there is noting wrong with the laptop and your problem is related to the power adapter.
If the adapter tests fine and output correct voltage, disassemble the laptop and remove the top cover.
As you see on the first picture, in my laptop the power adapter plugs into the DC-IN power jack which is connected to the motherboard via a harness.
In some models the DC-IN power jack is soldered directly to the motherboard.
Plug in the power adapter and measure voltage at the point where the DC-IN jack or DC harness (like in my case) connected to the motherboard.
If you are reading the same voltage as on the AC adapter, it means the power jack or harness works properly and the problem is related to the motherboard.
If there is no voltage, most likely there is a problem with the jack or hardness and it has to be replaced.
By the way, in some case the problem could be related to the fuse which is usually located somewhere very close to the power jack/harness connector. You can test the fuse with a multimeter.
If the fuse is bad, the motherboard will appear to be dead even if there is nothing wrong with the power jack and AC/DC adapter. If that’s the case, replacing the bad fuse should fix the problem.
December 7th, 2011 at 10:19 pm
Hi , i have a HP g62t core i5 laptop. it suddenly stoped working (it would not switch on) i plugged it in the charger but no LED light indicating charging. after playing around with it (opening and closing it) i plugged it in and surprisingly the charging light was on and the battery was recharging. but still it would not turn on although the battery was charging ( it was a bit warm). what could be the problem? motherboard or power board maybe? or could it be that fuse earlier talked about?
I appreciate your help.
November 29th, 2011 at 5:05 am
The fuses are usually, but not always, near to the power socket. But luckily most fuses do look just the same – white rectangles with power rating printed on top.
It is still possible for a laptop charger to show its normal voltage but to break down instantly or after a certain time, when under load running the mainboard, so just checking with a meter for 19v or whatever it may be rated as is not a guarantee its 100% a good/bad one. I find it’s mostly DELL and SONY chargers that do strange things when faulty.
A few here have asked if it’s there fuse? If charger & battery do work, and you still get no charging-up light, its 50% certain a fuse has gone…..but……
some laptops have 2 fuses, one for powering up, and another for the charging circuit, though on most modern laptops, they are so cheaply made now, the 2nd fuse is no longer bothered with.
Out of all the faults on laptops, the mainboard fuse is about the last thing to go though. Even direct burn-out short on a DC socket will rarely blow the fuse – a fuse is supposed to be a ‘weak point’ in a circuit to avoid further damage, yet I fix many many boards with major blown chips & components, yet only 5 have had blown fuses in the past 7 years I can remember of.
I’m currently working on an external battery charger to power up dead boards that cannot get charge – should allow for far faster diagnosis, well, that’s the theory anyway
*** Nathan, the rating should be written on top of the fuse, usually just giving an AMP rating 5 or 5A as an example, and a letter to indicate if fast blow or one of the several other kinds. Tracking down a fuse rating with no markings is far more complicated though
and often easier to find another board of the same and take it off that.
November 29th, 2011 at 2:30 am
sir my laptop compaq presario c700, has no power, ive check the power adaptor ok, ive check the power jack ok. ive check the continuity of the button flex it fine. then i keep on looking the fuse but i did not find any. now my laptop totally dead, please help. thanks
November 13th, 2011 at 5:43 am
sir what is the compatible fuse if idont have one of that….
November 13th, 2011 at 5:35 am
what the same can replace it…
November 7th, 2011 at 5:42 pm
@ joe,
How can I show? If you know where the fuse is located and know how to solder, you just desolder the failed fuse and solder a new one.
November 7th, 2011 at 5:36 pm
can you show us how to replace the power fuse please? because looks like is soldered directly to the motherboard.
November 7th, 2011 at 3:42 pm
@ Thamer,
Sounds like motherboard related failure to me.
November 7th, 2011 at 2:45 pm
I have a Dell laptop (XPS M1330). It will not turn on even though the battery is fully charged! When I do plug in the charger, the light on the charger turns off and stops working. Just flicking the switch at the wall turns it on again, but as soon as I put it back in the computer it turns off again. I tried to turn it on while it was plugged in but no battery and it didn’t work.
October 16th, 2011 at 8:08 pm
Hi
I can’t find the fuse on my DELL D600 motherboard .
Does existe absolutly a fuse near the power jack/harness connector ?
Thanks