Hi Alex, I am a electronic hobbyist, often watch your videos, with your knowledge and skills I learnt a lot and today I fixed a hard drive one of teachers and very glad that it worked out well. Just thanking you will be less to appreciate your sharing skills, knowledge and talent. I am glad that I bumped on to your videos and yes I used lots of flux 😊
I started at 20yr old to to have an AS Degree in electronics and not I'm 74 and still learning to ID the SMD components by watching you name them as you test them. I still have a steady hand to do the micro solder with your help of showing the componants and how you test them. Thank you.
The charging chip is the likely culprit... even if you jump the two MOSFETs, the charging chip needs to send an AC_OK signal to the Embedded Controller indicating that a charger has been connected to the laptop. That prompts the EC to instruct the 5v and 3v chip to start working
EC needs a standby voltage which is 3.3vdc and this is also true on a charging chip. The question is where is this 3.3vdc should come from? Those 19vdc before the MOSFET will likely have another path going through a dc/dc voltage regulator that will output another 3.3vdc and 5vdc those regulator and i we call that output as VDO, the VDO will only output if it receive a signal from EC to turn on. What other technician didn't realize is that the same regulator will output another 3.3vdc & 5vdc and it will be called VDA . These VDA will output the moment the regulator receive a 19vdc from the charger. So, any short from these VDA will not supply the standby voltage of an EC. I know this because i already troubleshoot a shorted VDA and its from Acer i7 laptop
@@pyotrilyichtchaikovskyii6638 the 5v and 3v are on a different rail. The charging ic controls 1 & 2nd mosfets plus the 1st and 2nd mosfets on the battery line. Super io checks the talks to charging ic to ensure all voltage, data etc is present and ok.
Once the satisfactory voltages have been met on the charging ic circuit and power good signal has been given then the 5v and 3.3 always on signal will be created via a series of buck regulators/switches that turn on and off and depending on off on off on off on off and depending on how quick they turn on and off will determine the Vout
I think we need to check the capacitors of the smps lines ( for leakage ) or the lines that control the gate of the mosfets ( for level of voltage ) or completely change the charging ic and see .
Alex, at 11:30 you can see the liquid metal has flowed down the GPU. Maybe it seeped under the kapton film and shorted the SMD capacitors. Please check it. Use isopropyl alcohol to wipe off the liquid metal residue from the kapton foil.
@@gattaca9287 Because its way more efficient! In a small laptop shell the high end components will produce lots of heat! Even 5 degrees improvement in the temperature of the main compute components may be critical for the better user experience! But it's also dangerous! Big companies like Asus could easily remove any possible short from spilling the liquid metal in that area by just covering the exposed caps near the cpu and gpu with silicone or other isolating material which will cost them penny's!
Good job mate! I didn't see that at all, before reading your comment! It could be the reason for the strange problem of that board! You may be the savior of this board! Alex is awesome! I hope he successfully return that board back to life!
Puting a wire instead of the two MOSFETs will not fix the problem because AC_OK will not be present. So to solve the problem just replace the two MOSFETs . All Asus laptops have this problem
What about a dead bios battery? Sometimes the tiny little battery that maintains bios settings and the RTC (realtime clock) module being dead would prevent the laptop from turning on, I actually experienced this a few times in the past.
Happen to me with an HP workstation .,... NO VIDEO, from one day no another. The IT guy was about to trash it. Took out the battery, discharged the motherboard and it workend after powering on. This trick came from OLD IBMs that suffer a lot from low CMOs battery. It shocked me that a modern HP workstation was still suceptible to this.
I would check the charge controller on the rear of the board, just left of the power connector. It controls the PWM signals to the MOSFETS. I couldn't read the numbers to look up the power, reset pins. Second, I would replace the low side MOSFET you removed. It shows signs of heat damage.
9:52 Is that solder bridging from one cap to the other? or is it plastic? Maybe this is the problem, or maybe the problem lies with the charging IC for the computer. 12:11 crack in the chip? or maybe hair
Hi alex you said before that you will create a section in the forum for schematic and boardviews are you still going to do it i have a lot of them and i will be in a look at the forum to provide for anyone asking .. salam . RIDA
You could replace the charger IC at 4:33. It is dead and you could check it on REGN pin when plug in adapter. If it is alive, it will generate around 6V on it.
Hi @12:24 I see a module that I think it's for WiFi. Could you remove it an test the board without it? I have laptop that was not power on and after changing many repair shops finally someone figured out. The Faulty WiFi module was the problem. Thanks
Besides the liquid metal, since passing 19V trough doesn't turn the PSU off it's unlikely a short after the mosfets. How much power is drawn from the PSU when bypassed mosfets? Of course something isn't opening the mosfet and only passes trough 4,6V, but what happens if you pass like 20V to the gate? Does it allow 19V trough then and if so using thermal cam you might spot the issue. If so then whatever is driving that mosfet is not working. There is always driving circuit for those mosfets, usually a chip near the fets. Of course there are other designs and things such as charging chips or components around those chips could be the cause. Since it is no direct short it will be difficult to find and likely a hailmary.
Hi if there’s no voltage in the gate of 1st mosfet, check the acdrv signal from charging ic, if there’s no schematic available try to look the manually the data sheet of the charging ic and use continuity mode of tester from ACDRV signal if connected to the gate of mosfet. The ACDRV signal is generated of 22v or 24v from charing ic, NOTE: N-channel mosfet is always higher than the source in gate signal
This is one of those cases where the short existed, BUT...as it can no longer be seen on the thermal camera, the short was so large that it already blew/opened/destroyed the component internally. This is one of the toughest faults to detect, as you would have to make sure the components are getting the correct voltage. I would pass on this one, not worth the time to diagnose, even with the schematics.
I'm confused. You jumped two drains. How did power get to the rest of the board without jumping to the last source. Isn't it like line and load on a gfci?
I didn't see you checking for 5v or 3.3v after jumping the power protection, maybe that should give you a clue of maybe a dead super io or something similar.
I don't know if he just got too acustom to the same faults he don't want to check for these things or he just don't want to teach us how to do it, check the power sources and if the super io is working
I would have checked the 3.3V power supply. If it’s not present obviously the laptop will not work. If I have to guess probably it’s missing, and should first try to investigate why. If it’s present probably the super io is faulty, happened to me in the past. Great video!
AFAIK if the 19V is missing, you can't have 3.3V because it is generated from the 19V. You need to have a working 19V rail in order to have 3.3V, 5V and so, but I might be mistaken.
@@amberonline24 No! 3.3v and 5v are usefull for SIO. Seraj is right. To be sure, you can mesure 3.3v on pson on keyboard or on button. If not 3.3v then maybe the charge chip or one step down 3.3v is the issue.
@@labibleatarilesitedesatari6724 In each and every laptop first +19v power rail is there then +3.3v low drop out supply activates which goes to SIO in order to be able to get +3.3v always (coil) supply and +5v always... +5v does not go to SIO. Correct me if I am wrong. So first voltage is 19v Vin to check on current sense resistor. 🙂
In MacBook I seen this problem when the voltage divide resistors gone bad, and their resistance increased from 47k ?? to 100+k ( as I remember ). Do you have a donor board as this one to check them ? Also 11:03 4 caps on the top, 2 from the right have a strange black dot on it
Did you get it fixed? IMHO the mobo was previously shorted and there is an open device, shunt resistor or current sense resistor. What does it do when the battery is installed and the charged is plugged in?
Oh! I can't wait to viewers ideas! I am not a smd soldering person. Just an amateur who likes to watch how Alex fix electronicks :-) So I am excited how far this repair will go.
One thing I have had a bad experience with is Kapton Tape. The material absorbs moisture over time and the resistance of the material goes down reeking havoc with sensitive control electronics. The circuits will behave unpredictively and I suggest you remove any Kapton from devices. Kapton was designed for use in space and not for a humid atmosphere like on Earth.
The only thing I can think of that will be stopping the proper flow of electricity to the main board will be a shorted capacitor somewhere. Usually when microcapacitors short out they can either act like resistors or just no powerflow at all.
Give the first two MOSFET are in effect a reverse polarity diode....with 19 V across the first one....gate drive is missing.....and what provides this " 20" V? You speak of.....there must be a bootstrap circuit somewhere
dear northridgefix in your video at 12:11 there is a crack black chip at the bottom right next to 1R0 125 28k silver block next to black 0 hms on the black chip its a small crack
Is it possible an inductor connecting to that mosfet is weak or bad cos there is no short but the voltage is low, or it could be a Feedback Resister that’s bad!!!
What board is?? ?? The model printed in the board if lucky can be find a schematic (or similar model) . Is the pwm circuit driver for the MOSFET (and probably the MOSFET itself) but can be anything (a single circuit or a bunch of sot 3 components) . If this don't work you don't have any voltage in the board .
What I say whit similar model is the same CPU (Intel have his configuration) and the same brand (asus use the same circuit for the same CPU in almost all boards changing a few components)
please check from where gate voltage is generated and why it is not generating gate voltage may it is a fault of passive component or gate controlling ic is faulty
I think the diode next to input mosfet is in short because there should no power if mosfets closed but there was. Also there can be super IO problem but need to check stand by powers 3v and 5v is present when after first mosfets injected power or after fixed mosfets issues.
Since there is no short to ground something might be eating the voltage. Maybe a volt regulator chip ¿ . You might probably see a blinking chip with your thermal camera at back of the board. Or a resistor that gone bad. Resistor will not return any voltage and will not show as a short. So check resistors around charging ic. And also around musfet
The first two mosfet is controlled by charging ic. If it is N channel mosfet (which most laptop have) then its gate supply should be approx 25v which is controlled by charging IC. If charging Ic requirement not complete then it will not 25v gate supply. If is P channel mosfet then gate supply must be low then source or drain. I am surely say that we should first check charging ic requirements. Hope for the best. I learned lot lots of things from your video. Thanks for sharing your most amazing knowledge & experience with us.
since the failure mode is not short I think you can deduct all ceramic caps are fine. it might be a burnt resistor or bad electrolytic cap as well as a ic related to power or embedded controller. maybe some diode. i am however just a hobbyist.
I currently have a Lenovo Legion 5 that is presenting in pretty much the same manner as his. But the MOSFET he removed, on my board I removed it and it is short. Measured board where MOSFET was, no shorts and getting 20V on second source, where I was getting 0V before. currently trying to find a substitute for the particular MOSFET that the manufacturer put on the board to begin with. trying to decide if I try that jumper from D-D like he did would be a good test. I'm a little apprehensive about it, though I am curious if the board will either turn on, or reveal the charging chip being shorted. On my board it is a BQ24780S I think.
when you dont have the 25+v on the frist 2 mosfets is because the charging ic is not working, you need to check the battery charging circuit and check the chargin IC, it is the one that send the 25+v to the first 2 mosfets
It looks like they use kicad to design this board. The footprints look familiar. Does some other cad tool have those footprints? (I’m talking about the silkscreen on sot23-3 as well as the elongated pads, also the silkscreen for 0603 and bigger caps/resistors)
Hello Alex sir. my laptop can't charge but cherging light is on. whole day plugin but onley charge 12% after opening the laptop still draing battery not useing AC power what's the possible cause for this problem. it's a ASUS s510uq. i hope you replay me.
Maybe get a board diagram or if not available you could support yourself with diagram of similar board. Often power supply looks the same or similar but it could lead to fining out the issue.
im no expert,i have seen videos of that liquid metal thermal paste cause odd problems pictured at 11,30 ,also the foam your were looking at 11.46/7 looked as if that chip as if it had got hot.i dunno thought id say
Retimer? Something telling the board that it has proper voltage, blown mini fuse some where, grounding plane for the power supply sometimes gets janked because of dropping while plugged in, reflow the charge port
at 9:45 what is that touching the capacitor's it looks like plastic but never sure since its hard to capture light reflections threw scopes good. other then that keep up the work love your videos.
Fault finding for shorts is obviously effective and deservedly profitable to repair, but it's only one failure mode. Power control on these is dependent upon micro controllers activating mosfets, reading current, sending serial data and "OK" signals to enable startup. Probably not worth your time and a customers money. You could identify all the integrated circuits around the power systems, check them with an oscilloscope to see which ones have data busses, check and interpret comms based on data sheets and narrow down the fault. It must either be a failed IC or a failed passive. Without schematics or reverse engineering it is only guesswork. Thanks for what you share!
Hi you might want to start by resting the bios by removing the internal battery (BIOS Battery) then shorting the battery terminals on the motherboard for at least 30 seconds. I might sound silly but modern laptops have a tendency of freezing BIOS
Can you please Look at 6:50. .. if you Connect a Part heats Up ob the right Side ;) I think the DC connector get warm too becouse something Change the reflaction ...
I never found the culprit. I also replaced the charging iC with few other other components but it was a no Fix. I had another one that came in the very next day with the same issue and again it was a no Go. I'll try again on the next one.
@@NorthridgeFix Thank you for taking your time to answer. What wired is that if I connect the battery I have 2.85 on the power button shorting to ground go to 0 and jump to 3.2 but not powering on. Again many thanks
@@NorthridgeFix Hi again The laptop is working from the battery, I injected 14 volts to the battery, took few times for the battery to open and charge, now the laptop is working from the battery but even if i bypass the 2 mosfets it still not charging even if there is 19.5 on the main power probably there is short between the battery and the main power, maybe to add a diode will help, or maybe just to build a 14v charger and inject directly
@@NorthridgeFix I found the problem. There is double diode the supply vcc to the charging IC, PD8900, testing it in diode mode shows ok but it doesn't open or passing the 19 to supply vcc to the chip. very hard to find
hp, dell, and lenovo mobile workstations (zbook, precision, thinkpad). everything else is hit or miss, even with those companies. And for sure stay away from all Apple products. If their laptops don't die their software updates will bork it somehow so you'd have to buy a new one.
im having the same problem with mine never did get it fix because it had to be sent off but i was told it had to do with the charge controler on the bord mine will run on the battery but power wont go from the power pug to where it has to go to run the board most likeyl it will run on a charged battery. the problem is at the plug
At 12:11 it seemed like the IC next to the inductor had a small crack. Could also have been some dirt
up
Great eyes
Up
Saw it too
Hi Alex, I am a electronic hobbyist, often watch your videos, with your knowledge and skills I learnt a lot and today I fixed a hard drive one of teachers and very glad that it worked out well. Just thanking you will be less to appreciate your sharing skills, knowledge and talent. I am glad that I bumped on to your videos and yes I used lots of flux 😊
On 12:11 I think the surface of the IC is carcked.
I took a look at that as you said and it does look like a crack (well spotted)👍
Doesn't seem cracked, seems like an hair or lint, not a crack.
On video most of the cracks are a visual effect but this one indeed looks cracked. Great find!
Eagle eye
Seems like it. Nice spotted. I hope he checks it out.
I started at 20yr old to to have an AS Degree in electronics and not I'm 74 and still learning to ID the SMD components by watching you name them as you test them. I still have a steady hand to do the micro solder with your help of showing the componants and how you test them. Thank you.
The charging chip is the likely culprit... even if you jump the two MOSFETs, the charging chip needs to send an AC_OK signal to the Embedded Controller indicating that a charger has been connected to the laptop. That prompts the EC to instruct the 5v and 3v chip to start working
Agree with that
EC needs a standby voltage which is 3.3vdc and this is also true on a charging chip. The question is where is this 3.3vdc should come from?
Those 19vdc before the MOSFET will likely have another path going through a dc/dc voltage regulator that will output another 3.3vdc and 5vdc those regulator and i we call that output as VDO, the VDO will only output if it receive a signal from EC to turn on. What other technician didn't realize is that the same regulator will output another 3.3vdc & 5vdc and it will be called VDA . These VDA will output the moment the regulator receive a 19vdc from the charger. So, any short from these VDA will not supply the standby voltage of an EC. I know this because i already troubleshoot a shorted VDA and its from Acer i7 laptop
I agree also, I already fix a lenovo laptop that has charging ic problem.
i was going to write this.. totally agree..
Bios corruption bios will cause that too, bios talk to the EC also.
Most of the time, first two mosfets are controlled by the charging IC. Try replacing the IC.
Not most. 100% of the time they are and to the super io (ec)
I second this and I think it enables the regulator chip that supplies the 5v and 3v lines as well.
@@pyotrilyichtchaikovskyii6638 the 5v and 3v are on a different rail. The charging ic controls 1 & 2nd mosfets plus the 1st and 2nd mosfets on the battery line. Super io checks the talks to charging ic to ensure all voltage, data etc is present and ok.
Once the satisfactory voltages have been met on the charging ic circuit and power good signal has been given then the 5v and 3.3 always on signal will be created via a series of buck regulators/switches that turn on and off and depending on off on off on off on off and depending on how quick they turn on and off will determine the Vout
I think we need to check the capacitors of the smps lines ( for leakage ) or the lines that control the gate of the mosfets ( for level of voltage ) or completely change the charging ic and see .
Alex, at 11:30 you can see the liquid metal has flowed down the GPU. Maybe it seeped under the kapton film and shorted the SMD capacitors. Please check it. Use isopropyl alcohol to wipe off the liquid metal residue from the kapton foil.
You're right bro...Sharp Eyes 👀
@@eftekerahmed7299 Thank you, it comes with the profession!😁
Probably the right spot, well done ! Why the hell do they put metal paste instead of a non conductive ??
@@gattaca9287 Because its way more efficient! In a small laptop shell the high end components will produce lots of heat! Even 5 degrees improvement in the temperature of the main compute components may be critical for the better user experience! But it's also dangerous! Big companies like Asus could easily remove any possible short from spilling the liquid metal in that area by just covering the exposed caps near the cpu and gpu with silicone or other isolating material which will cost them penny's!
Good job mate! I didn't see that at all, before reading your comment! It could be the reason for the strange problem of that board! You may be the savior of this board! Alex is awesome! I hope he successfully return that board back to life!
Puting a wire instead of the two MOSFETs will not fix the problem because AC_OK will not be present. So to solve the problem just replace the two MOSFETs . All Asus laptops have this problem
9:50 what is this blob just at the anode of the AL-Cap?
That's what I was going to ask.
This is the most interesting video you posted so far. Why? Because I have encountered this issue and never figured it out. Is there a part 2 to this?
What about a dead bios battery? Sometimes the tiny little battery that maintains bios settings and the RTC (realtime clock) module being dead would prevent the laptop from turning on, I actually experienced this a few times in the past.
Sounds reasonable.
I don't think so, often, these notebooks take power to the bios from the main battery if it's not removable.
Happen to me with an HP workstation .,... NO VIDEO, from one day no another. The IT guy was about to trash it. Took out the battery, discharged the motherboard and it workend after powering on. This trick came from OLD IBMs that suffer a lot from low CMOs battery. It shocked me that a modern HP workstation was still suceptible to this.
what is the blob just below the 22uF cap? 09:45
I saw this as well but the metal cap and smd cap are on the same rail.
I would check the charge controller on the rear of the board, just left of the power connector.
It controls the PWM signals to the MOSFETS. I couldn't read the numbers to look up the power, reset pins.
Second, I would replace the low side MOSFET you removed. It shows signs of heat damage.
Alex did u check the voltages while only battery connected.
@9:30 just above the current sense resistor there seems to be a missing component and @12:11 ic looks cracked
I don't think is missing, I think it is default factory.
Good eye! I missed that crack first time watching.
Check 3.3v on the switch if not available verify if the 3.3v and 5.5v circuit is ok, the Start-up ic also needs checking.
9:52 Is that solder bridging from one cap to the other? or is it plastic?
Maybe this is the problem, or maybe the problem lies with the charging IC for the computer.
12:11 crack in the chip? or maybe hair
First thing I thought of was a crack in the chip. I even paused and went back. Looks like a crack to me.
Was going to comment on the blob but it seems both pads are on the same plane so maybe it doesn’t really matter?
Hi alex you said before that you will create a section in the forum for schematic and boardviews are you still going to do it i have a lot of them and i will be in a look at the forum to provide for anyone asking .. salam . RIDA
You could replace the charger IC at 4:33.
It is dead and you could check it on REGN pin when plug in adapter. If it is alive, it will generate around 6V on it.
You're right
bq24780s
Is that a solder blob bridging the big electrolytic cap and the large surface-mount cap at 10:00?
Seems to be either Charging IC or 3V/5V voltage regulator issue
Hi Alex.
Check for 3.3 volts on bios and super io chipset.
If there is 3.3 volts then problem either bios or super io chipset.
Good luck
Without 19v main power rail how can you get 3.3volts
at 10:07 in video there was a solder blob looking object between a larger cap and smaller one. Maybe was a short there at some point?
I was about to comment on that but I think they are on the same plane so they are connected together already, I think :-)
Hello Alex, at 10:06 i see a bulge of solder between the electrolytic cap and the other cap?? Or maybe just dirt?
Hi @12:24 I see a module that I think it's for WiFi. Could you remove it an test the board without it? I have laptop that was not power on and after changing many repair shops finally someone figured out. The Faulty WiFi module was the problem. Thanks
Besides the liquid metal, since passing 19V trough doesn't turn the PSU off it's unlikely a short after the mosfets. How much power is drawn from the PSU when bypassed mosfets?
Of course something isn't opening the mosfet and only passes trough 4,6V, but what happens if you pass like 20V to the gate? Does it allow 19V trough then and if so using thermal cam you might spot the issue.
If so then whatever is driving that mosfet is not working.
There is always driving circuit for those mosfets, usually a chip near the fets. Of course there are other designs and things such as charging chips or components around those chips could be the cause.
Since it is no direct short it will be difficult to find and likely a hailmary.
@10:01 dont know if thats dirt or what not below the silver cap seems like it touching the other cap its prob just dirt know
Hi if there’s no voltage in the gate of 1st mosfet, check the acdrv signal from charging ic, if there’s no schematic available try to look the manually the data sheet of the charging ic and use continuity mode of tester from ACDRV signal if connected to the gate of mosfet. The ACDRV signal is generated of 22v or 24v from charing ic, NOTE: N-channel mosfet is always higher than the source in gate signal
This is one of those cases where the short existed, BUT...as it can no longer be seen on the thermal camera, the short was so large that it already blew/opened/destroyed the component internally. This is one of the toughest faults to detect, as you would have to make sure the components are getting the correct voltage. I would pass on this one, not worth the time to diagnose, even with the schematics.
i found that in hard way..
Working on Huawei nova 2i mother board
❤
I'm confused. You jumped two drains. How did power get to the rest of the board without jumping to the last source. Isn't it like line and load on a gfci?
I didn't see you checking for 5v or 3.3v after jumping the power protection, maybe that should give you a clue of maybe a dead super io or something similar.
I don't know if he just got too acustom to the same faults he don't want to check for these things or he just don't want to teach us how to do it, check the power sources and if the super io is working
I would have checked the 3.3V power supply.
If it’s not present obviously the laptop will not work.
If I have to guess probably it’s missing, and should first try to investigate why.
If it’s present probably the super io is faulty, happened to me in the past.
Great video!
AFAIK if the 19V is missing, you can't have 3.3V because it is generated from the 19V. You need to have a working 19V rail in order to have 3.3V, 5V and so, but I might be mistaken.
First +vin (19v) should be ok then only +3.3v will be generated
@@amberonline24 No! 3.3v and 5v are usefull for SIO. Seraj is right.
To be sure, you can mesure 3.3v on pson on keyboard or on button. If not 3.3v then maybe the charge chip or one step down 3.3v is the issue.
19v is the main voltage.. you check 3v and 5v when you have 19v..
@@labibleatarilesitedesatari6724 In each and every laptop first +19v power rail is there then +3.3v low drop out supply activates which goes to SIO in order to be able to get +3.3v always (coil) supply and +5v always... +5v does not go to SIO. Correct me if I am wrong. So first voltage is 19v Vin to check on current sense resistor. 🙂
11:30 is that thermal paste or liquid metal? If liquid metal, thatd be shorting all those caps on the cpu.
Yo. @12:40 what do you test on the gate of MOSFET please ?
Maybe you could check the Diode next to the 2 Mosfets you removed.
In MacBook I seen this problem when the voltage divide resistors gone bad, and their resistance increased from 47k ?? to 100+k ( as I remember ). Do you have a donor board as this one to check them ?
Also 11:03 4 caps on the top, 2 from the right have a strange black dot on it
When you added the jumper, make sure it touches the middle pad. might be sensing power good.
I had the similar problem with the 4-6v on the main power rail, the problem was in the first MOSFET. It had source shorted to the gate.
look at the solder joint 10:16 maybe it's shorting out or blocking the 19v to go thru...
Did you get it fixed? IMHO the mobo was previously shorted and there is an open device, shunt resistor or current sense resistor. What does it do when the battery is installed and the charged is plugged in?
Oh! I can't wait to viewers ideas!
I am not a smd soldering person. Just an amateur who likes to watch how Alex fix electronicks :-) So I am excited how far this repair will go.
One thing I have had a bad experience with is Kapton Tape. The material absorbs moisture over time and the resistance of the material goes down reeking havoc with sensitive control electronics. The circuits will behave unpredictively and I suggest you remove any Kapton from devices. Kapton was designed for use in space and not for a humid atmosphere like on Earth.
So..where is the solved video?
The only thing I can think of that will be stopping the proper flow of electricity to the main board will be a shorted capacitor somewhere. Usually when microcapacitors short out they can either act like resistors or just no powerflow at all.
Alex, whats the model number of the laptop?
Give the first two MOSFET are in effect a reverse polarity diode....with 19 V across the first one....gate drive is missing.....and what provides this " 20" V? You speak of.....there must be a bootstrap circuit somewhere
dear northridgefix in your video at 12:11 there is a crack black chip at the bottom right next to 1R0 125 28k silver block next to black 0 hms on the black chip its a small crack
Is it possible an inductor connecting to that mosfet is weak or bad cos there is no short but the voltage is low, or it could be a Feedback Resister that’s bad!!!
Like others wrote, need to check 3.3 around super IO, and check Super IO when try to start motherboard...
At 1.01 check for component 156 1E for short, seems there is a feedback circuit next to its line.
Sometimes a capasitor if it does not give a solid reading means it's damaged.. Even if it does not give a short bip
I think you must check charging IC (BQ Chip) that usually as a voltage source of the gate first power mosfet
You are right that the charging ic is the main issue
What board is?? ?? The model printed in the board if lucky can be find a schematic (or similar model) . Is the pwm circuit driver for the MOSFET (and probably the MOSFET itself) but can be anything (a single circuit or a bunch of sot 3 components) .
If this don't work you don't have any voltage in the board .
What I say whit similar model is the same CPU (Intel have his configuration) and the same brand (asus use the same circuit for the same CPU in almost all boards changing a few components)
please check from where gate voltage is generated
and why it is not generating gate voltage
may it is a fault of passive component or gate controlling ic is faulty
I think the diode next to input mosfet is in short because there should no power if mosfets closed but there was. Also there can be super IO problem but need to check stand by powers 3v and 5v is present when after first mosfets injected power or after fixed mosfets issues.
hello, watch your video at 10:05 between the 25v capacitor and the SMD. That might be the source of your problem. Cordially.
Since there is no short to ground something might be eating the voltage. Maybe a volt regulator chip ¿ . You might probably see a blinking chip with your thermal camera at back of the board. Or a resistor that gone bad. Resistor will not return any voltage and will not show as a short. So check resistors around charging ic. And also around musfet
The first two mosfet is controlled by charging ic. If it is N channel mosfet (which most laptop have) then its gate supply should be approx 25v which is controlled by charging IC. If charging Ic requirement not complete then it will not 25v gate supply. If is P channel mosfet then gate supply must be low then source or drain. I am surely say that we should first check charging ic requirements. Hope for the best.
I learned lot lots of things from your video. Thanks for sharing your most amazing knowledge & experience with us.
What a nice insight. You are correct
since the failure mode is not short I think you can deduct all ceramic caps are fine. it might be a burnt resistor or bad electrolytic cap as well as a ic related to power or embedded controller. maybe some diode.
i am however just a hobbyist.
I just had a laptop with a similar issue. I ended up having to replace both the charging port and the Power Management IC.
I currently have a Lenovo Legion 5 that is presenting in pretty much the same manner as his. But the MOSFET he removed, on my board I removed it and it is short. Measured board where MOSFET was, no shorts and getting 20V on second source, where I was getting 0V before. currently trying to find a substitute for the particular MOSFET that the manufacturer put on the board to begin with. trying to decide if I try that jumper from D-D like he did would be a good test. I'm a little apprehensive about it, though I am curious if the board will either turn on, or reveal the charging chip being shorted. On my board it is a BQ24780S I think.
when you dont have the 25+v on the frist 2 mosfets is because the charging ic is not working, you need to check the battery charging circuit and check the chargin IC, it is the one that send the 25+v to the first 2 mosfets
It looks like they use kicad to design this board. The footprints look familiar. Does some other cad tool have those footprints? (I’m talking about the silkscreen on sot23-3 as well as the elongated pads, also the silkscreen for 0603 and bigger caps/resistors)
Hello Alex sir. my laptop can't charge but cherging light is on. whole day plugin but onley charge 12% after opening the laptop still draing battery not useing AC power what's the possible cause for this problem. it's a ASUS s510uq. i hope you replay me.
Maybe get a board diagram or if not available you could support yourself with diagram of similar board. Often power supply looks the same or similar but it could lead to fining out the issue.
im no expert,i have seen videos of that liquid metal thermal paste cause odd problems pictured at 11,30 ,also the foam your were looking at 11.46/7 looked as if that chip as if it had got hot.i dunno thought id say
Retimer? Something telling the board that it has proper voltage, blown mini fuse some where, grounding plane for the power supply sometimes gets janked because of dropping while plugged in, reflow the charge port
Possible dead Super IO (start up chip)
at 9:45 what is that touching the capacitor's it looks like plastic but never sure since its hard to capture light reflections threw scopes good. other then that keep up the work love your videos.
Looks like a solder blob, but even if it is a blob, I think that capacitor it is connected to that component. But it may be worth to be looked at.
Best part at 7:00 keep your goggles handy before watching it.. ..😂😂
put back the jumper wire and measure all power capacitors. maybe dead resistor cuts power from ICs
Hi ! did you have voltage on input of power rail / VCORE ?
Fault finding for shorts is obviously effective and deservedly profitable to repair, but it's only one failure mode. Power control on these is dependent upon micro controllers activating mosfets, reading current, sending serial data and "OK" signals to enable startup. Probably not worth your time and a customers money. You could identify all the integrated circuits around the power systems, check them with an oscilloscope to see which ones have data busses, check and interpret comms based on data sheets and narrow down the fault. It must either be a failed IC or a failed passive. Without schematics or reverse engineering it is only guesswork. Thanks for what you share!
Somotimes those eight timer chips come lose from the board because of heat try checking those legs.
Nice video Alex!! Tell me, why do you wear gloves when doing some repairs?
Hi you might want to start by resting the bios by removing the internal battery (BIOS Battery) then shorting the battery terminals on the motherboard for at least 30 seconds. I might sound silly but modern laptops have a tendency of freezing BIOS
What of a board that has just been programmed and no Bios have been set yet?
Can you please Look at 6:50. .. if you Connect a Part heats Up ob the right Side ;)
I think the DC connector get warm too becouse something Change the reflaction ...
Also like to add that when I opened it there was liquid metal spill on parts of motherboard and no mosfets check shorted.
Alex I think ur problem is the gate drive on the mosfet is missing. The gate drive usually comes from the power controller chip . Thats my input
Did you find the problem? I received one exactly the same with the same problem, I already tried to replace the charging IC but didn't work
I never found the culprit. I also replaced the charging iC with few other other components but it was a no Fix. I had another one that came in the very next day with the same issue and again it was a no Go. I'll try again on the next one.
@@NorthridgeFix Thank you for taking your time to answer. What wired is that if I connect the battery I have 2.85 on the power button shorting to ground go to 0 and jump to 3.2 but not powering on.
Again many thanks
@@NorthridgeFix Hi again
The laptop is working from the battery, I injected 14 volts to the battery, took few times for the battery to open and charge, now the laptop is working from the battery but even if i bypass the 2 mosfets it still not charging even if there is 19.5 on the main power
probably there is short between the battery and the main power, maybe to add a diode will help, or maybe just to build a 14v charger and inject directly
@@NorthridgeFix I found the problem. There is double diode the supply vcc to the charging IC, PD8900, testing it in diode mode shows ok but it doesn't open or passing the 19 to supply vcc to the chip. very hard to find
@@computersrepaircotesaint-l7407 can you show me where this is please?
you have to cheek charge ic and its circuit because the charge ic if works will give the too mosfites that you take them out the gate to work
Any follow up to this repair?
If not getting 25v on the gate..something must be wrong with controller...check the vcc or vinput the controller.
Hi at 4.16 is that a damaged component?
If you pause the video at 10:03, there is something that may be bridging those 2 caps the small surface mount and the larger polymer(?) cap
hi Alex try replacing PM IC seems like all mosfet gate controller not functioning it could be pm ic or pch or cpu
Now i am doubting my asus laptop 💻. Can you suggest which laptop brands have top notch electronics?
Which laptop brand is genuine and reliable which has best hardware build that is not likely ro die easily
hp, dell, and lenovo mobile workstations (zbook, precision, thinkpad). everything else is hit or miss, even with those companies. And for sure stay away from all Apple products. If their laptops don't die their software updates will bork it somehow so you'd have to buy a new one.
What is the name of this motherboard?
WHAT IS THE ENDING ????? Fixed or return to SENDER ???
It's cool that you posted it for community input instead of just calling it a no fix
Every time you solder, I smell burning. Could you get a bigger fume extractor? :-))))))
im having the same problem with mine never did get it fix because it had to be sent off but i was told it had to do with the charge controler on the bord mine will run on the battery but power wont go from the power pug to where it has to go to run the board most likeyl it will run on a charged battery. the problem is at the plug
you should check vin of the charging ic acdet line and regn pins
Change both mosfets that you took out, the problem is one of the is partially shorted that is why you have 4.8 V, i have found that problem before
Can this be a bios issue?
It could be a crucial component is missing from the board that's not allowing power to get through.
I've found some Asus laptops with BIOS problems that appear to be dead. No power and no lights. And some faulty mosfets don't short.
I'm a Newby but I would change charging ic or a resitor issue around charging ic
What termal are u using?
I love that always get asus ads for these videos