HP Laptop No Power - Troubleshooting Short circuit - Watch component blow on camera

in this video we're gonna be working on an hp specs x360 that came in for no power this one is not the usual usbc charging port it's the one that is circular the blue plug that goes in and customer mailed this over because there's no signs of power anywhere on the board so the first thing i'm going to do is quick physical inspection on the board we'll start with quick physical inspection and then we will move on to thermal camera and then we'll test some components on the board to see what's going on i'm just looking for possibly blown components or discolored components i just want to see if there's anything unusual on the board because a lot of times when there's something wrong on the board it's obvious and other times the fault is not obvious which is more difficult because we have to do a lot of measurements and we do not have any circuit diagrams for this laptop so everything must be done based on experience and physical inspection with the help of the thermal camera of course okay so far the board looks mint i do not see anything obvious on the board this is the ssd drive 256 gigs and this is the bias chip right here firmware everything looks good here oh oh look at this we have a blown component we have a long component see that hole in the middle of the component that's a 10 or 0 10 ohm resistor probably most likely an 805 size smd okay so i think we're going to change that component i do have a 10 ohm 805 resistor in stock and i do not want to use hot air to remove that component because i did not remove the motherboard of the housing so we're gonna use our hot tweezers and we're gonna also test capacitors at random in this area to see if we have a short anywhere on that board but let's go ahead and replace that component add a tiny bit of lux and that way we do not have to remove the board of the laptop the question is how did that component fail i have no idea we do not know what went on with this laptop to cause this filter or this resistor to blow and that's exactly the same resistor exactly the same resistor how did i know that how did i know the size was eight of five [Music] very nice meter in diode mode i'm going to test capacitors at random [Music] just to see if we have a short anywhere no short and it looks like we have a short here meter in resistance mode what's the reading on this guy that short zero ohm zero ohm so it's a short on here that caused the resistor to blow most likely if we touch the gate it's testing good what if we test here we also have a short i look at the way this capacitor looks what happens if we plug the battery in right now and try to power it on i mean i do not like the way the battery looks on the customer's laptop it's wavy we have a battery here that we're going to use and this is a good flat battery it's not wavy like the customer's battery i just want to see what happens if we plug our battery and it's still not powering on even though this battery is charged let me plug the charging cable i'm going to monitor that component while plugging that cable [Music] yeah you see we saw that in real time that's what i wanted to do we saw that in real time like i said that component is not going to blow by itself there's something causing it to blow right now it's obvious that we have a short on the capacitor next to it right now what we can do is we can inject voltage on that capacitor and see what gets hot on the board we're going to use the voltage injection tool and we're going to connect the ground to any of the ground points here on the board maybe i can connect the clip to a screw so ground is connected to a screw right here and now we're going to inject voltage at the mosfet or the capacitor that is shortened to ground look at that four amps being drawn we need to look at the thermal camera we're going to inject voltage 1.2 volts and we're gonna monitor and see what gets hot on the board let's go ahead and inject 1.2 volts at the capacitor that is shorting to ground this is getting hot right here so short is not coming from the mosfet that is next to the cab but rather it's coming from right here a mosfet so i pointed my probe right over here and what got hot is this or the short could be coming from somewhere on bottom of the board maybe the short is not coming from here heat is being generated from this side of the board but maybe the short is coming from somewhere on the bottom here i'm going to inject 1.2 volts again and see what happens i want to monitor those caps the big ones this whole area is getting hot let me increase temperature boundaries i mean this is the inductor the coil okay let me increase the temperature boundaries a bit more inject 1.2 volts and see what happens this whole area is getting hot well i think what i'm going to do is remove that coil just to see if the short is coming from the mosfets or if the short is coming from the lower part of the board here okay the inductor is out meter in diode mode let's see so the short is coming from the bottom here sure it's coming from here and not from the other side of the board because look at this other side of the board is clean and the side of the board is the one that has the short look at the pad follow the pad it's everything inside here it's everything here that has the short okay so we eliminated the lower side of the board being the problem and now we can solder the inductor back okay inductor is back in place and now maybe we can dissolder this then this or vice versa and see if the short is coming from those mosfets those three are not shorting to ground and this one is i mean this cap is short into ground and this cap is actually going to the ic here so it could be that this ic is our problem or any one of those two is causing the problem i think i'm going to ask big boss to remove the board i do not want to work on the board while it's still inside the laptop i do not want to burn anything on this laptop i'll be back okay so i asked big boss to remove the board and he did and right now our short could be coming from either this chip or any one of those two mosfets we do have a short here on this cab but not anywhere else so a short from this cab is likely to to this chip if the cap itself is not short into ground last time we were working on a samsung galaxy s9 plus we removed two chips from the board and the problem turned out to be the cap it's usually really not the cap but let me start with the cap just in case this cap is shorting to ground and i highly doubt that the problem is this cap but let's start with it let's test to see if we still have a short you see the problem is not the cap because some people asked in the comments when i was doing the s9 plus how come you did not start with the cab first you remove two chips and not the cap because based on my experience it's likely not the cap and this goes to show you that the short is really not the cap itself i mean those caps do short but from my experience it's usually the chip it's more likely the chip than the cap and since that cap has a direct connection with this chip i have a very strong reason to believe that the problem is this chip so let's go ahead and remove it let's remove the chip and see if the short is coming from this ic and let's see if we still have a short do we still have a short and the shortest car the short is gone so the ic is what's causing the short let me test here also i mean we still have a short here on this cap okay so now with this ic out i'm gonna inject voltage on this cap and see what gets hot on the board now we're gonna inject voltage right over here and we're gonna see what gets hot jump over to our thermal cam and right now the board is hot because we applied hot air okay so right now we want to ignore the mat this is the mat here the mat is out because of hot air but the board starts from this edge right here so let's inject 1.2 volts on that shorted cap and see what gets hot same okay what i'm going to do is dissolder those two mosfets that would be the fastest way of doing it the solder those two mosfets and we'll take it from there and let's remove this guy as well microscope camera was not on great i desoldered this mosfet and i desoldered this mosfet and we also removed that shape from before so now we have three ics off the board and we're going to go ahead and test to see if we still have a short on the side of the board because this component when we inject 1.2 volts on this component this area is getting hot so these components are linked with this cap let's see if we still have a short on this cap if not then most likely the problem is one of those two mosfets a meter in diode mode and look at that the shot is gone the shot is gone so it's one of those two mosfets that is causing the problem what about this ic this ic may still be good we're gonna solder it back on and we'll see we still have unleaded solder on the board but that's okay it's a tiny ic and it shouldn't matter and now with this chip on let's go ahead and test this cap as well and the shirt came back on the shorts came back on so we're gonna remove that ship again the best thing to do now is to see if we have a donor board or a donor laptop that is similar and we can extract those components from that donor board or laptop and get this board to work i take the chip back out and if we test again shirt is gone okay so i'm gonna go and look in the bin of laptops and see if we have something similar that we can extract the chips from and i'll be back okay so i was able to find a donor board exactly the same one so we're gonna be using parts from that board and what we can do is we can go ahead and test to make sure those parts on the donor board are good i mean this chip is the bq chip i know from the nintendo switch a bq chip is a charging ic but it's not the same one as the nintendo switch this one is uh bq1775 it's a five pin on each side connector the one on the nintendo switch is six pins otherwise i would have used the chip from the nintendo switch if it matched meter in dive mode let's make sure that this ic is good we're going to test this cap here and it's not short into ground chances are this is good and let's test this cap here and it's a no shot great so we can use all three chips from this donor board in the meantime let's go ahead and prep this board i already applied some flux here and we're going to apply flux here and here we're going to prep the pads by adding leaded solder okay that's good enough and just a tiny bit in the center here let's start by desoldering the first trip the bq chip and we're gonna solder that ship right here now we're gonna press down okay and this is soldered down nicely let me just get rid of some of the excess solder on this cap here very nice now we're gonna solder those two mosfets and let's do the other one and we can clean up clean that solder glove later but let me grab the other component right now we also have to change this blown resistor that we changed before and it blew again so let's grab another one add some flux here and we are on our way to have any good functional working laptop very nice and before we reassemble the board let's go ahead and test make sure we do not have a short on this cap right here meter in diode mode right probe on ground and we do not have a short anymore and let's also test if we have a short on this cap and we do not and those are the three ics i took off i put them right here one two three and that's it i'm going to give it a big boss reassemble and i'll be back in a few minutes so big boss reassembled the board and it's a no-go i noticed that this capacitor is now shortened to ground again because of those two mosfets those two mosfets are now shortened to ground and they have gone bad we did resolve the short by replacing those two mosfets but after he plugged the charging cable in those two mosfets went bad again uh right now we do not have a circuit diagram and we do not have a board diagram for this board i already spent enough time on this board and this is turning out to be a rabbit hole that i do not want to continue working on because i mentioned this in many videos before i cannot afford to spend the whole day working on one single board it's not efficient it's not practical it's not economical we have a lot of repairs that we need to get done can we figure out what's causing those components to go bad probably yes if i want to spend enough time working on this board i can probably figure it out we're going to deem this repair and no fix and we're going to mail this back to the customer i hope you enjoyed the video even though it's no fix don't forget to like and subscribe and we'll do something else in the next video you

Channel: NorthridgeFix

Views: 553,870

Keywords: hp laptop repair, short circuit troubleshoot, short circuit, diagnose, hp spectre x360, hp spectre no power

Id: XBAn2Ck8GeE

Length: 23min 30sec (1410 seconds)

Published: Tue Mar 30 2021