Samsung NP-N150 burned component

[lezsimply]

Hi guys! Need help in identifying burned component of this laptop.

When laptop arrived I've tested power adapter and it has no output. After fixing the adapter I plugged it and laptop still has no power. tested adapter output voltage is ok. so I ruled out adapter as the problem.

I decided to disassemble laptop and saw burnt marks along dc jack line. I have obtain a diagram but not sure if it is the correct one since there are no markings on the motherboard. replaced the burned component an smd capacitor valued 10nf 25v C502. When I pressed power button it immedidately burned the component again.

Just wanna know if I was right thinking that the part is valued 10nf 25v on C502 or might have read the schem wrong. I uploaded the diagram and image. please check it out. Thanks a lot!

[lezsimply]

Re: Samsung NP-N150 burned component

oh sorry I uploaded only part of the schematic. This is the pdf version.

[whaldsz]

Re: Samsung NP-N150 burned component

yes you are right, it's 10nF.

[lezsimply]

Re: Samsung NP-N150 burned component

Thanks sir whaldsz. If I replaced it with the correct value, there maybe other component causing it to spark and burn.

I removed those two capacitors and yet when I plugged the adapter it still spark. I also tried changing b500 with working one it still spark. Is there a possibility that AO4807L (Q501) is causing the short? Usually when I fix sparks like this I looked at the components connected before the burn one not after.

I have already tested the adapter, if it is faulty it would have burned right away. But adapter still outputs 19.4v

thanks again

[khaahk]

Re: Samsung NP-N150 burned component

Part of the pcb (between copper layers) might have turned into coal, which is causing the sparks.

[whaldsz]

Re: Samsung NP-N150 burned component

Could you check the resistance between the coil b500 to ground?

[lezsimply]

Re: Samsung NP-N150 burned component

meters says 031

[whaldsz]

Re: Samsung NP-N150 burned component

Try to remove the coil b500 and test the resistance both of the pads to ground.

If q501 is not overheating, it's obvious that the short is prior to q501. You may also remove it to be sure.

[lezsimply]

Re: Samsung NP-N150 burned component

ground to top pad =1. ground to bottom pad =004. Cannot check q501 if hot because as soon as I plugged the adapter it sparks. I'm going to try and remove q501 if it still sparks. thanks

[whaldsz]

Re: Samsung NP-N150 burned component

if that's the case, probably the dc jack is shorted.

[lezsimply]

Re: Samsung NP-N150 burned component

have you guys encountered laptop adapter that shows correct output voltage but shorts the laptop when plugged?

[whaldsz]

Re: Samsung NP-N150 burned component

yes of course. it's a short circuit protection of the AC adapter kicking in. does your laptop works on battery?

[lezsimply]

Re: Samsung NP-N150 burned component

I didn't manage to try the battery because its drained. before this laptop came, the owner told me she forgot to charge it because her son took it off 3 days before this happened.

just removed q501 same thing happens. and also removed power jack from motherboard but haven't found any replacement. Is it ok to direct the voltage on the motherboard without using power jack? this is the first time I'm going to try this.

does capacitor like 100nf 25v cause a short on a series? thanks very much sir!

[whaldsz]

Re: Samsung NP-N150 burned component

yes it's ok, but take note of the polarity. is the dc jack the cause of the short?

before you do this, you can try and test the coil to ground resistance to verify that the short is gone.

[lezsimply]

Re: Samsung NP-N150 burned component

tested coil b500 =002 in meter. dc jack has no short. I think short is coming from adapter. If spark still present I'm gonna recheck usb ports. thanks for your patience.

[lezsimply]

Re: Samsung NP-N150 burned component

replaced dc jack same problem. used different adapter same effect. I also directed the voltage without using power jack spark/smoke is still there.

I noticed that smoke/spark is coming from the second layer of the pcb just below the b500 coil. it seems that components are not the ones burning, its underneath them.

no short on usb port. dc jack position is right next to lan. Could lan port cause short like that? I'll post an image of the dc jack area later. thanks!

[lezsimply]

Re: Samsung NP-N150 burned component

Removed lan port but smoke still present. I'm running out of ideas. I have attached an image of all the components I removed to isolate the problem. And also what do you call the component circled in orange. thanks!

[khaahk]

Re: Samsung NP-N150 burned component

Good macro picture not available? If you have a microscope, then take a closer look. I think
that the pcb has burned inside the board, turning into coal, which is conducting material. You have to open the pcb by removing the first layer and clean the coal out of there. If needed resotre the top layer to add the components. Then if all ok, close the place with some non conducting varnish. Hopefully there aren't any traces in the internal layers of the board.