Laptop motherboard, diagnose & and repair tutorial
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Laptop motherboard schematic diagram with BIOS BIN and power sequence |
hello so we are back tuesday and it's a beautiful day outside what do we have today we have a gaming laptop okay this is a rog laptop horizon 7 and nvidia graphics rog zephyrus okay the gaming laptops they are expensive so uh we we are we are trying to figure out the fault or we are just give them more time compared with the normal laptops just because they're more expensive the first thing is what we ask the customer especially when it's a gaming laptop if if if they open the laptop already because many times you'll have uh let's see if it's a water damage spot inside and the customer opened the laptop and you see the spot you'll clean this the spot hopefully you know he is thinking it will work and if we are not seeing that spot we are we are missing the fault so it's it's kind of obvious and on this case the customer said he opened the laptop but he didn't do anything inside okay so let's open this and fix or first let's check yeah let me grab the charger i know it's dead it's just a dead laptop i broke in the job yesterday and the customer said oh i know you i see you i saw you on youtube does make me feel bad you know in a case you fix the laptop everyone is happy when you don't fix it you make me feel bad plug in the charger and we have no light nothing pressing the power button nothing happened it's just that okay so let's open this the model of the laptop is ga 502d okay let's try and fix it you know what i seen randomly browsing youtube i seen last week um a live stream from apple they were launching the new ipad and i was impressed so on the ipad pro they said the new ipad pro the big one they achieve 1000 nits brightness and hdr high dynamic range to achieve something like that on um it's it's a lcd screen led screen it's hard and i was impressed how they figure it out so basically on any lcd or really led screen you have the backlight leds or whatever on the side and you have a diffuser behind of the screen so they remove the diffuser and they fit another screen behind of the screen which is also connected to the graphics so it's a screen made with leds behind of actually screen and that's how they achieve hdr and and now a thousand it's brightness which i was impressed you know if you are looking online if you are looking like to buy a monitor let's say you have a camera like i have the black magic and i'm looking for an external monitor and i was looking for external monitor if you are looking to buy high brightness external screen like seven inch there they are very expensive they can go easily over one thousand pound so i was impressed by the uploader i'm not apple fanboy you know i love the technology okay those two screws are not working let's see what we can do the squeezy the screw is flexing okay so the customer feed the wrong screws on the on the holes we'll see after that wow look at that here's a proper gaming laptop nice design so check here yeah you have a heat pipe from the processor and graphics to the boat both fans you have graphics memory pipe which is going here and you have the second pipe from the graphics and processor which is going on this side of the of the fan proper nice design proper nice design now look at those speakers big big speakers that's a nice laptop okay so let's plug the charger and see what's going on what do we check first so plug in the charger here what do we check first first we check 19 volts first on the charging port and then following the 19 volts power rail so ground you can get ground from anywhere and we have the charging port and we have nothing the charger is plugged let's check the charger and i have nothing so the charger is gone come on that will be awkward it's a big charger hmm 20 volts check on the multimeter on the screen 20 volts okay this can be another issue if we plug the charge under the voltage goes down so we have 20 volts let's plug the charger well let's check the voltage now and we have nothing so basically we have nothing you know why because the charges they have a protection in a case of short circuit they will cut down the power so if the board is shorted let's come with the power supply on the same point here on the charging port i shall not take that out with the battery inside but by mistake i took it out so let's see power supply 20 volts around 1 amp minus plus and we have a short so the limit is 1.6 amps the voltage 2.4 doesn't mean the short is not here and then we have two mosfets next to the charging port so i really have i have hope for this laptop to be fixed because usually a shorter board is more easy to fix compare with another board let's say you have a another board the voltage is dry but it's not starting which is most likely a superior issue i prefer a shorted one and what happened in my microscope yeah it's on so you have the charging port okay just follow the follow the route here so check that you can see on this case the ground is separated from this truck so the plus is the solder here on this truck the big truck which is plus it's coming to the first mosfet then you have the second mosfet is going to the second mosfet and from the second mosfet yeah from the second monster you have that current resistor and from here you have your main 90 volts power l this one this one should be 19 okay uh pretty easy and most common design you'll find this design 99 of the laptop 99.9 even the apple laptops they have same input design okay there are few laptops low power laptops usually small laptops they replace the first mosfet with that diode but you still have the second mosfet the purpose of this those mosfets are just for protection here they cut the power down in case something happened but not on this case like like how you can see the board is shorted but the mosfets are doing nothing so one more time let's go with the power supply 20 volts so on this case we know already it is a short you can see there 1.6 is going the limit and the voltage goes down to 2.4 so actually the voltage here is a reflection of the the resistance okay checking here we have the ball 2.3 volts and checking on the output we have 1.6 volts which is very bad and checking after the first yeah that's that's that's bad that's bad that's bad you know let me explain why i give you one second you know i will explain i will properly explain you why one second ah okay let me explain why because playing with the power supply can be easily but same time you have to learn to read the results and the results are bad comparing the with other cases you remember we made so many you know shorter capacitor on the main power rail do you think here it's a shorter capacitor a very low probability let me take down my jacket it's getting hot here okay and you'll think sorry but it's a sure there so obviously must be a capacitor well it's not short short has so many meanings so let's say again yeah you have the input circuit you have the charging port okay and you have plus and minus minus is ground so just ignore the minus just focus on plus plus is going let's say in the first mosfet you don't really need to know what kind of the just see that that mostly first the most i just i want to see them like a switch nothing else okay i have a switch the symbol of the switch and you have the second mosfet that's that's how i want to see them because it's more easy to understand because they function like a switch yeah they are not fast switching they they are just switches electronic switches if they if you can take out the the most specific feed relays then will be same thing they will do same thing and after that we have that current sensor a resistor which is this and usually uh from here is going to your power management chip yeah and here you have your main 19 volts power rail okay so on this case you have your main power rail from here the laptop is taking power so you have a lot a lot of power supplies a lot i'll give a few examples and also you have a lot of capacitors so here you'll find probably around let's say 20 30 capacitors like this here connect connected the power rail and also connected straight to the the other power supplies yeah like we are like three three point three volts you have five volts you have uh one what ddr4 is 2.4 volts i think yeah the processor you have a lot of power supplies in many cases in most of the cases you have one of this capacitor which is shorter to the ground short meaning on this point you'll have 0 ohms checking with with the multimeter left check ohms ground and we're checking on this point here here and we have 0.8 ohms and you'll think it's a short checking with the power supply it's a little bit different story if you put this and you calculate it's a different story what you see from the multimeter and actually the resistance which you can calculated by the current the voltage and you calculate the resistance so the voltage here is 1.6 okay 1.6 volts with one point something amps the resistance is quite high so the probability to have a shorted capacitor is very low usually a short meaning this that's a short and you can see on the power supply i have like 0.2 volts that's a short yeah this is not a sure this is a resistance yeah but why is bad i will explain why it's bad let's say you have a power supply how is a power supply 99.9 of the power supplies you have one mosfet you have the second mosfet have the connection you have the ground here and from here you have your coil and then you have a capacitor and this is supplying power to something okay and those mosfet they have a driver but just ignore the fact yeah let's say let's say this mosfet is shorted just let's say let's let's think this moves very short what will happen your power rail which let's say it's ram one yeah 2.4 volts is ddr4 if i if i'm not wrong if this was pretty short and you do a trick like me you applying 19 volts because i came with the 19 volts power supply here you apply 19 volts exactly on your arm because this is shorter remember so let's say you have a shorter mosfet so you come with 19 volts on a point where it's supposed to be 2.4 that's kind of you know you kill something now the trick is to use a current limit like in my case i'm using a current limit like one amps and something that's not it is important to work with low currents so in a case you in a case you have something like that you have a limit with one point something amps you can't really burn anything let's say this power supply is actually the processor one or is the graphics one or you can't burn them with one point something amps okay but i don't think it's the wrong one let's say if this is the ram power supply then there should be 2.4 i shall have here if this is shorter i should have here over three volts and i don't have three volts i have one point something so most likely yeah you can have let's say you can have a shorter capacitor which is shorter than has a high resistance but on this case the probability is very low actually the probability to this power supply to be from the processor or the graphic is very high based on the voltage uh on the voltage reading so yeah that's the trick okay so again let's get the power supply now it will be very helpful to have a thermal camera we don't have a thermal camera but let's open this uh we need access here you see that even the coils look these are the the the processor stages behind of the heatsink and here the graphics very nice design very nice design let's try to take them out that's why i always told you you know what use a current limit and use a current limit this has a seal here and the seal is intact so does mean no one opened this before using a current limit it will give you some leverage so you can play a little bit and be protected at the same time what do we have we have the fans the battery sorry let's unplug the battery forgot about the battery but it's shorted anyway so we have no voltage on the laptop okay we have the wi-fi antenna let's unplug the wi-fi antenna and we have a screw behind of the hinge i always read the comments on the channel i can't answer on on the you see you when you look on the video you see the comments on that video but there are like over 500 videos and the people are still leaving comment on the old videos so it's kind of tricky to read all the comments but i'm trying and uh there are a lot of people they they said okay i'm learning i'm learning and i'm happy with how you explain so it's it's looking complicated but actually it's not that complicated because i would say everyone can fix anything related with the power but not with a digital uh thing you can't touch there it's it's software and hardware together even the manufacturer can't fix let's say a broken truck between the ram memory and the processor or uh miscommunication between the chipset and the graphics of the pro it's it's you can't you can fix power related program problems but that's all okay let's unplug the fan okay look at the processor big brush are a small processor on a big graphics possible we found a problem because i was looking and i said what's that shiny thing there probably can't see it possible the fall to be here what's that there that doesn't look normal what do you think so maybe it looks normal i know look some flux there looks like it's on flux though but anyway that's not the way how you find that fault maybe that's the way okay the visual uh okay i understand that but let's ignore that fact that monster can be good let's call me the power and try to find out actually it's a bad idea to come with the power if you have the high side mosfet the monster connected to the 19 volts if you have that one shorted you come with the power what do you think will get hot the processor but this is a nice laptop look how many stages are here you have five nine nine phases for the processor and two for the graphics this is a nice laptop how do you find a fault on this case you can remove the the mosfets each at a time and see when the shortest disappear or let's try and come with the with some current yeah because that processor can handle few amps we can't really burn the processor so easily plus here 1.6 amps i'm just curious if the processor is getting warm or hot or any of those mosfets no actually the graphics so i can feel the graphic chip warm really the graphics is not the processor is the graphics let me get this let's try to figure it out let's get a multimeter ohms and let's check the graphics resistance in the processor and we have like 4.2 ohms on the processor and thus can be normal many people are tricked believing it's a short but it's not that's the internal resistance of the poster and that seems to be right and the graphics let me check here on these coils and it has 0.8 ohms which i don't believe is right wobble here 32 ohms which is fine 32 ohms which is fine so those power supplies are for the graphics clearly but they are fine means those are for processor for face and probably those are for graphics okay so the output of the coil or you can check on the capacitor is like 0.4 0.8 which is kind of low now this is compared with the ground let's compare with the plus yes i'll take this out and i'll compare with the plus you know that current resistor which is our main 90 volts power l and with the plus it's like 0.3 ohms so yeah we have a high side mosfet burnt most likely the one which we see in here let's remove this because this looks dodgy so everyone else looks fine but on this one this looks like some flux there or something looks dodgy to me so let's remove that mosfet and see if the short is still there okay so we removed the mosfet wow this is bad this is a dual mosfet and i don't have something like that okay let's see so we remove the mosfet let's see if the short is not there anymore we can check with multimeter or power supply same thing let's check with the multimeter and it's nothing like 47 kilo ohms so if i come with 19 volts let's call in 19 nothing it's taking no power you can see so that one was shorted but the issue here this is a dual mosfet so inside of this you have two mosfets so just things on my schematic this one the both mosfets are on the same capsule okay that's why it's a dual mosfet we have to find one because otherwise we can't fix it we have to find a dual mosfet somewhere robo apple what they are using we can find our dual atmosphere here so we have one gate there and that's all one gate and one gear if in rog laptop it will work with apple mosfet let me check to be sure it's a dual mosfet it is a dual mosfet a dual motor has two has two gates here so we have a dual mosfet it's a bit of flux it's perfect let's see if the rog laptop it will work with apple technology let's see what we have though should we finally solder this thing back come on let me grab some flux okay seems to be fine how do we check we need a heatsink probably is getting hot very quickly let's try let's feed the heatsink and we replace the thermal paste after that and use thermal paste on that mosfet it is time after that but first we have to see if it's working or not obviously we have to know if it's working or not because keep in mind you are using a deeper different type of mosfet which is not necessarily bad usually they are compatible but can have like different switching time can have a different internal resistance a few things can be different by now apple they are using high quality components so we should be fine okay that's okay let's plug the screen let's check one more time with the power supply and our mosfet is not good why i shall check from before most likely the configuration of the mosfet is different compare with uh with what we have here okay so we have to find another one because here it can be same capsule but you can have different configuration of the pins okay i took out the mosfet let's try to find another one looks like apple one is not good for us i'm trying to find a gaming motherboard but not necessary gaming gaming but a good one do all mosfets hmm ugh that's not a dual mosfet hmm dual mosfets now this is a single what we can find should be some gaming motherboard around here i know samsung has some dual monsters but not this one usually if you have a motherboard and you can see a coil with one single mosfet that's clearly a dual mosfet so or nothing yet come on i do almost fit so huh okay let's see what it's with this apple one and what we are doing wrong here why is not working with apple one let's take these out let's try to study the configuration a little bit yeah but this is not a dual but yeah it is it is a dual monster it is a dual mosfet let's see the gates are on this side as i mean the gates has to be also be on the other side which is right here the plus the output is from the middle and it's okay no the coil one second let me be sure i'm doing the right things here so the coil is here does the coil robo here the coil is here it is here does the plus small one it is a plus this one it is a plus it's not ground so ground must be here it does ground was this pin here what is this well i'm doing something wrong i am doing something wrong no these are not normal dual mosfets let's have a look online so what mosfet is this alk 190f what's what nothing nothing online okay let's try five zero one five zero one five zero one eight sg here yeah these pop up let's have a look together so i don't get it one second let me switch let me switch but that's our most fat yeah well that's our most fat and the internal connection where is the schematic on the internal connection is here this one so we have one mosfet i have the second mosfet so these three pins are all together and this pin here yeah so we have one gate one gate but this pin what this spin is doing this is from okay so this has to be plus here has to be the coil on this these two are together one second so here is the coil which is right okay here is the coil let me see where is the ground one second yeah that's the ground if this is plus oh the ground is not okay there should be the ground for the second pin this one is from the middle of the mosfet which is which is the coil yeah it's not yeah according to the schematics the p number two is the same with those three pins yeah it's the same circuit right gate return so gr is gate return this one so probably this is the feedback which is going to the driver and it's taking from the middle of the of the mosfet actually from the coil actually for this ship online yeah uh let me switch i'll check on um on ebay because looks like it's not a usual mosfet we can buy this copy ebay yes only from china oh that's crazy that's sick so it's nothing what we can do the part we can order from only from china that's the part five picks three point something pound and the postage okay only nothing from uk only from china well i suppose i'll stop this video now and we have to order the part i don't think will work because clearly the driver is taking the feedback yeah from the from the coil i don't think will work but we can try the laptop should come on and goes off probably or it will work but obviously you can't leave it like that you have you know it's it's you need you need power you need power but just for testing just to see the behavior okay just to see the behavior just to see the behavior where is the charger the charger is here power on and nothing because probably the child we have to reset the charger remember was zero volts last time yeah we have the power on light and we have we have picture on the screen actually it is working without that mosfet which is insane and is loading the windows you can see but i'll stop this now because the processor when the processor route will ask for power the power will not be there yeah the laptop it is working which is insane because it's taking feedback but it's taking the feedback from the coil and uh no actually the feedback is missing because that pin is not connected but he's working with that that's crazy so you know what i mean how can i do it like that let me switch it's insane i don't understand why this is working because you see this pin is connected here here here and here and here you have the coil yeah this pin 567 you have the coil so basically this pin can be straight connected to the board is same thing but because the i remove the i remove the mosfet on this pin is no feedback it's just a empty pin and the driver is not getting the feedback they still working i mean the way how the laptop works there should be a power good signal power good signal driver is sending the signal to the superior say look the power supply is up and running but not on this case not on this case it looks like the driver is either ignoring the feedback or is not speaking of the superior pretty weird but at least we know the cpu is good we see in picture we've seen the cpu is good the graphics is good so all what is left yeah on this is to order the that mosfet to order the mosfet and replace the mosfet but i know this is a well it's it's it this will be working so i i'm sure i can order and i'll fit it and it will work okay so i'll stop this video because we see in the laptop one the laptop is working i will order the part i'll replace the part and obviously it will be working it's working even now without atmosphere and yeah but it's the waiting time probably will be up to one month to order the the chief from china but at least you've seen how you can diagnose how we can you know try to figure it out a problem oh wait no that one is not from cpu is from uh from graphics yeah because the graphics was getting warm yeah so half of this starts for processor and half are for uh gpu and most likely these probably are for a forearm memory uh graphic memory okay but we know at least we know we seen picture on the screen we know the laptop is fine nothing else is wrong okay so i'll stop this video now thank you for watching like and subscribe if you like the video you see it's not complicated to diagnose the things we're keeping keeping keep in mind it's nice to have spare like i don't have any advanced gaming motherboard here if i will have probably i'll have that mosfet okay see you on the next one
bye
