Dead Motherboard: Total Power Loss
Laptop does not start. Is it bad power jack or power fuse?
Let’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?
![Laptop top cover removed]( "pdiag1.jpg")
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.
Let’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.
No power Problem
Diagnosis, Cause and Remedy:The first thing I did was testing the power adapter with a multimeter in order to verify whether the power adapter is the one that's causing the no power problem or not. The supply voltage indicated on the power adapter is 19v, when I tested it, the supply voltage is just normal. Since the power adapter is just okay, our concentration now is on the laptop itself. In order to ascertain whether the motherboard of the laptop or other peripheral devices which is connected to the laptop causes the no power problem, we have to disassemble the laptop piece by piece. After unscrewing all the laptop parts, I individually pull out each peripheral devices. After completely taking out all devices which is connected to the laptop. I now separated the motherboard in order to be tested. But first I clean out all the dust from the motherboard for this is also a one factor which causes the motherboard electronic components to be shorted. Because when dust gets thick it will become a conductor.
So you need to be aware of this, every time you disassemble a laptop motherboard you need to free the motherboard from all dust, to be sure not the dust is the element causing the motherboard's electronic component parts to be shorted. After cleaning all the dust from the motherboard, I scan all the components to see whether there are any dry joints or not. Dry joints means loose or poor solder connections. Poor solder connections on a laptop motherboard usually occur when your laptop is already well-advanced in years. I did not find any poor solder connections on any part of the motherboard, but for contentment I just carefully resoldered all the SMD components especially on the power section.
Note: All laptop nowadays is designed on a Surface Mounted Device or SMD mode, and this is rarely have dry joints. But for satisfaction I cautiously resoldered all the SMD components particularly the SMD components near the dc power jack.
After resoldering all the sections that needs to be resoldered, I inserted the dc power plug adapter to the dc power jack and see whether the power comes up. Unfortunately, the condition of the problem remains the same. I now tested all the electronic parts on the motherboard to find out whether there are any shorted electronic element parts which causes the no power problem. After testing all the components that could be tested merely with a multimeter, I could not find any shorted parts. The only parts that I still not checked was the dc power jack and the fuse.
The final step that I did was testing power jack from input to ground for short. When I tested it, voila! the problem found because it is really shorted. I used x1 range of my multimeter to see the fault and either way there's a deflection. When I go on testing the fuse, I found that the fuse was also open, the rate of the fuse is 5.5 amperes and upon further inspection I found a shorted diode.
The reason why the power jack terminals were shorted is because of the shorted diode that is connected to the power jack. Replacing the diode and the fuse brings the laptop to life.
So you need to be aware of this, every time you disassemble a laptop motherboard you need to free the motherboard from all dust, to be sure not the dust is the element causing the motherboard's electronic component parts to be shorted. After cleaning all the dust from the motherboard, I scan all the components to see whether there are any dry joints or not. Dry joints means loose or poor solder connections. Poor solder connections on a laptop motherboard usually occur when your laptop is already well-advanced in years. I did not find any poor solder connections on any part of the motherboard, but for contentment I just carefully resoldered all the SMD components especially on the power section.
Note: All laptop nowadays is designed on a Surface Mounted Device or SMD mode, and this is rarely have dry joints. But for satisfaction I cautiously resoldered all the SMD components particularly the SMD components near the dc power jack.
After resoldering all the sections that needs to be resoldered, I inserted the dc power plug adapter to the dc power jack and see whether the power comes up. Unfortunately, the condition of the problem remains the same. I now tested all the electronic parts on the motherboard to find out whether there are any shorted electronic element parts which causes the no power problem. After testing all the components that could be tested merely with a multimeter, I could not find any shorted parts. The only parts that I still not checked was the dc power jack and the fuse.
The final step that I did was testing power jack from input to ground for short. When I tested it, voila! the problem found because it is really shorted. I used x1 range of my multimeter to see the fault and either way there's a deflection. When I go on testing the fuse, I found that the fuse was also open, the rate of the fuse is 5.5 amperes and upon further inspection I found a shorted diode.
The reason why the power jack terminals were shorted is because of the shorted diode that is connected to the power jack. Replacing the diode and the fuse brings the laptop to life.
