Dell AIO 7777 motherboard repair - Wow, this is a nice board...

hello so we're back and this time we have a nice job here this is like a desktop motherboard it's a all-in-one the PC motherboard which has like a normal CPU so uh we have an interesting job here the customer sent me only the motherboard so what the customer is saying the customer is saying the computer working on some point uh uh the next day the computer hasn't started so let's have a look who are the customer send us here so we have the charging port okay that's strange because the customer said he put the power button okay let me try to find the power button one second okay that's really strange because I cannot find the power button so I have the charging port I have the charging port but not the power button so it's no power button so I believe the customer forgot to put the power button so what do you think about the board I mean it looks fine huh okay this is a nice board with a nice socket I can't see band pins there but you see that's a board where actually you can replace the CPU if the CPU is getting faulty yeah so what do we have here we have a we have a cheap uh GPU probably Nvidia yeah this is a nice Dell board it's a Dell Inspiron 777 all in one series four sevens yeah good so I will say let's try and fix it so let's plug the charging port and let's see what this is doing before we are starting today video sponsor is PCB way PCB way is one stop solution based on the fact they have all kinds of pcbs 3D printing CNC sheet Metals all are available on their website now you will find a link on the description to have a look on their website now the beauty is if you register on this website you have five dollars gift which is about 10 boards so actually you can order 10 pcbs for free all you have to do is to pay for the postage now the question is are we gonna use uh the PCB way and the answer is very simple yes so we start with electronics on the other channel learning electronics you remember so instead of buying electronic kit yeah because that's why I was buying electronic kits because you know the board is the hard part components we all have components so instead of buying electronic kits I will just you know order the PCB and solder the components and it will be the same thing okay so don't forget you can have a link onto the video description and check their website now let's go back to our board let me plug a charger no I don't want to plug the customer charger the customer charger the customer charger is crazy it's insane 180 Watts so it's about 10 10 amps charger so you remember we said we cannot diagnose things we like turn off charger every mistake it will be like the last one so let me plug the power supply we have our power supply let me find an adapter yeah it's hard to say if it's HP or Dell but she'll do the job so let's switch the power supply to 19 volts plug in the power and it's taking 60 70 milliamps that's not right um on a motherboard when the motherboard is off all what it's on is the 3.3 volts power supply which is supplying power to the AC chip so we have like 70 milliamps and doesn't look good yeah doesn't look good at all now what do we have here where is the ECG because most likely this one I believe we are dealing with the DC chip it's not that one or something else yeah smcs yeah that's the one and the chief set check here you have the chief set here no it's not warm uh let me grab the thermal camera because what is taking 70 milliamps we should see it on the thermal camera okay let's wait one second this is a proper nice motherboard so you have two HDMI you have a bunch ESP you have a network card this is the hard drive huh this is the SSD right yeah it must be huh okay so with thermal camera what we can see oh Lord huh what is here so whatever is here it is hot but it's not on this side of the board must be on the other side let's have a look together huh so what do you think we have we have two transistors like normal transistors which wow they are not hot okay so that's the input secret I can see it now yeah and the next mosfet is probably on the serial mode with the it's on the serial mode with the power so check here the power connector here you see red so this must be plus plus you see you have few inductors there then it's going to the mosfet and those two transistors are getting hot now we don't have two Moses on this board from a simple reason we don't have battery oh yeah we do have a lot no okay the most parallel mode you can see so you have one more set here and also we have a diode there and we have one mosfet here so you see it has two Moses on the parallel but doesn't have the second mosfet which is not necessary if you don't have a battery on this board so on this side of the board is fine you check the dot current sensor check there yeah check check here the the current sensor you see how big it is so it's passing the current and here it's outputting the look what is going it's going to a small chip yeah so we have our mosfet here and from the Moses we have a diode and the diode can be that can be we're gonna check that so this diet is connected to ground you can see it's like a salad diet in case the voltage is going uh crazy up so here those transistors are getting hot and I don't understand why so we have the output yeah we have the charging port we have the inductors then we have one mosfet and from the output of the mosfet wait what is the solution here you can see so some this has liquid damage huh wait what is with this liquid there or someone work on this board I'm not sure I'm not sure but there is liquid let me power off the power supply let me try okay so what do we have here here let's check together I'll get a multimeter why those two transistors are getting hot um what is the reason so we have ground so the ground is here right there must be this one here and we have the input and check on the screen the input we have 19 volts and on the output we have nothing we have zero volts we can see now how those transistors are getting hot if they here we have zero volts that's a good question anyway you can spot anything weird on this mosfet we have three pins together at the input that means it's a channel P mosfet and on the gate we have 19.6 now you see on the channel P mosfet the voltage here has to be lower compared with this one with the with the source so if we have 19 that's mean the mosfet it will not drive the power so in order to drive the power has to be at least probably six volts lower good let me disconnect the charger let's go with the multimeter so with the multimeter so here is fine check on the screen zerohms I mean like literally zero it's exactly the yeah it's exactly the multimeter resistor probably 0.1 ohms you can see so I will say the main power really shorted where do we check the main power L very simple we have those capacitors you can see we have dual mosfets so those are the CPU power supplies and we have dual motors and we have capacitors let's come with some current um what do you think let's call me some current I'll get the power supply I'll let the charger because the charger it will give me the ground let's lower the voltage oh about one volt a bunch of arms so coming with the power supply after the mosfet is yeah check that 2.6 amps let's hire the current you know my power supply yeah like 2.6 times but you cannot check here you remember from here you have the current sensor and after that is going to the main power rail so I'm going to check here so here we have 3.2 amps 0 0 9 and here one volt okay so here is the Plus 2.6 amps so this board is taking 2.6 amps with one volt let me grab the thermal camera now if it's a dead mosfet you know what does even matter you have a swappable CPU it doesn't matter it plays the monster replace the CPU and all good so must be a capacitor like oh what is that what is there a LOL okay okay okay so can you spot the problem huh you know I'm just asking can you spot the problem you can't um Can you spot the problem we have an exploded capacitor you can see there it's exploded let's go under the microscope Let's uh replace the the capacitor and yeah we are good to go we can test the board huh so what do you think about that capacitor what happened with that capacitor you see it does look how black is the board here you can see it so you see that's a reason why the laptop work and the next day didn't work anymore the capacitor exploded okay of course we're gonna replace the capacitor but not in this video remember no capacitor no shorter capacity if I replace the capacity Thrasher has is just another chance for that capacitor would blow up or go shorted I make them a favorite I'm just joking of course we're gonna replace the capacitor on another video so the board is taking 400 milliamps you can see so the board just came on yeah the chipset is getting hot yeah yeah the body is working so right now is nothing what I can do you know just the board need the CPU and that's all so everything is fine what do we have here here we have the GPU which is on uh what do we have more here we have the we have one chip which is on we have power supply switch there on the CPU power supplies they are on obviously it's not CPU those power supplies they are on the chipset it is on the smcs cheap it is on yeah so the board is up and running we can check the voltage on the power supplies but obviously the board it will get stuck without the CPU you cannot pass the test we don't have the CPU and raw memory right yeah raw memory is missing also but the fault was clear I mean it's not like okay this is one fault and then you have another fault no was a shorter capacitor on the main power rail so here we have one volt maybe you have this board and you want to know the voltage you see here here you have one volt if you're looking to program the bioship you have 3.3 volts then here we have five volts then here we have 3.3 volts then here you have 1.8 [Music] here you have 1.8 volts okay so here you have yeah 1.5 volts I'm not sure for one 1.5 probably for vram right yeah probably and here you have one volt so here you have one volt and here you have one volt so if you have a dead power supply you can use just one wire to carry the one volt and you solve the problem um okay okay this was a easy job because all what we had was a blow up capacitor you can see this one oh yeah you can see it the thing I didn't Spot It but yeah maybe it's a good idea just to analyze the board before you start I mean yeah it was kind of tricky you know was like like a lot of white and black here so hard to be seen but yeah it's making sense why the computer died okay so stop now I will say thank you for watching like And subscribe if you like the video like always and see on the next one bye

Channel: Electronics Repair School

Views: 25,768

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Id: LoWjagACirc

Length: 18min 49sec (1129 seconds)

Published: Sun Sep 17 2023