The problem with main rail shorts on gaming laptops - LFC
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- เผยแพร่เมื่อ 5 เม.ย. 2023
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I'm not sure how you can make a video about laptop repair simultaneously interesting, relaxing, entertaining and informative, but I hope you don't stop.
Thanks for taking time to capture, edit and post. I enjoy watching your professional approach to troubleshooting and (when possible) repair.
@MookieMc: It is for comments like yours and also those of other colleagues that this channel fascinates me and as long as young Graham continues to upload this type of content, I will be his faithful subscriber. All the best.
I'm Up for the Rabbit holes and dead ends Videos, for all us newbies and hobbies that's pure gold we will learn and will know that not all repairs are a win. great content thank you.
Rabbit holes or dead ends make ok videos. Can't tell you how frustrating fix videos are when you've tried them but nothing works. Wins are great but fails teach just as much, at least in the mechanic fields. I always told my troops not to cover up a mechanical error because now I can teach them something else/new. Thanks for the video, always enjoy watching
Sorin: Ok, let's try to flash the BIOS with the new tool
Haha,pa nije ovo Sorin electronic😂
LOL, stop bullying Sorin, he's simply fascinated with his new toys, he just came a little late to the party
I love sorins patient
Sorin is a hero in repair, but his head revolves around bios these days.😂
Sorin is a genius with lots of electronic knowledge
Given that I've killed my first attempt at a component level repair of a shorted 3.3V rail via liquid damage, I so appreciate videos like this that give me more knowledge and context to what I should look for the next time i try it.
That was an interesting dive, thank you. Successful repairs are great but diagnoses of failures can be both interesting and useful, as this video shows. Think "Hmm... I remember watching Graham diagnosing a fault similar to what I'm seeing and he proved it by doing X, so I'll do that." and "Hmm... I wonder if Graham has had a look at a similar issue? Let me check on TH-cam..."
One thing I hate the most is reading a book only to find out it is missing the last few pages, with that in mind, I enjoyed watching you follow this fault to a logical end, it was educational and interesting. Thank You...
Done watching, thank you very much for the detailed troubleshooting procedure. I hope you will soon have a mini-series for Schematic & Boardview-free Voltage/Power Rail Tracing[12V/18-20V Main Voltage Rail, 5V, 3.3V, CPU/GPU Core Voltage Rail, DRAM Voltage Rail, IGPU Voltage Rail, System Agent/Northbridge Voltage Rail, PCH Voltage Rail, BIOS Voltage Rail, Battery Power Rail] and BIOS Bin File Editing.
Fascinating as always keep up the good work
Yet another very informative video. Thanks!
18:30, i think you are right in the money, thats why after changing the Mosfet you still have a short on the induction side (CPU side) but not before the Mosfet on the main power rail, i'm learning so much from your channel, i was able to fix a spare laptop board that i have for a project fallowing your voltage injection video (it was a shorted cap... as always lol), thank you.
Great watching your videos. I have noticed, when you are looking for shorts using your meter in ohms range, you don’t zero the meter. By shorting the leads and press the REL button will compensate for lead resistance. Sorry if you that already
hey Adam great vid lots of interesting info thank you for sharing
Very entertaining, thank you. 🙂
I do wonder why the manufacturers don't have any circuit that will sacrifice itself to protect the CPU and GPU. It would probably be far cheaper for the end user as they might not then need a new motherboard
I assume the answer to your question lies in the question itself. Manufacturers don't have that circuit, because they don't get to profit off the sale of a new motherboard if they do put in such a circuit.
its a simple circuit for over voltage protection it is called crowbar.. they do not use protection intentionally
Sometimes, you get the bear.
Other times, the bear gets you.
Thank you for explaining things throughly in detail. I had similar scenario
Similar ACER nitro laptop (AN 515 model) that died on me after 3 months of purchase which i sadly voided the warranty. Already gone to 3 repair shops and they all that the cpu is most likely dead. I think they already come up with the same situation before. Now i am finally accepting that CPU can die and i just throw away my very first job salary away buying acer cheap laptop. I seriously hated it now when it happened to me. I know others are fine with purchasing acer and i congratulate them. but im not gonna be the one anymore to buy their stuff
Again, thank you. i now accept i had to say goodbye trying to revive whats dead
New intro music is growing on me
This guy is amazing.
Well done 👍👍
Isn't this a design flaw? I think so! Why do all the mosfets have a thermal pad to the heatsink except the one that shorted out? Surely a tiny bit of copper and a thermal pad doesn't cost THAT much, especially in an expensive gaming laptop, right? Acer, you wouldn't shave off any penny you could to save cost, would you now?
Wow! How do you know / learn this stuff? I'm officially hooked - thanks.
I have one of these machines with a similar issue, but I think mine is slightly different as it does charge the battery but won’t power on. Any ideas where I can look to find the issue ?
Love the channel.
If there was that much at stake, the Acer would have found a way. You must climb the steps to Mount Seleya.
What I find strange is when I do repairs like this it’s not the end, I remove cpu and put another one on. So I don’t see the problem here, only if customer doesn’t want to spend for the work. I mean in a lot of cases the mosfet is at fault, most repairs I do are 70% or more a mosfet problem.
I've had this exact model in the shop and after removing a shorted cap it had the same behaviour as yours. I let it turned on for a while hoping it was just ram learning ecc. But nothing. Then I've found out this is a common behaviour for this laptop: black screen, keyboard lit but nothing. After resetting cmos, turning on/off a few times (long pressing ecc) it turned on. But yeah a shorted MOSFET is far more likely to have killed your CPU
why they don’t put veristors or some kind of protrction if mosfets short out?
atleast i see parts that can be reused, ram, wlan card, battery, screen, fans.
Exellent video sir
I've got the same laptop... owner must've OC'd and didn't consider power draw the higher the OC goes.
I found that really interesting actually
Hello 👋, ineed help please, i have dell inspiron aio 3280 not read hdd sata , but reading usb with cable data usb , i was flash bios chip without copy backup, now my computer is not power on just blinking 2-1 light orange , any solution , thank you.
Contrary to popular belief, this video was useful.
I'm having a similar issue with a gaming laptop I'm working on. The main power rail was shorted to around 3 ohms. After some searching, I found a shorted mosfet near the dedicated GPU. I removed it and the main power rail resistance is back up in the Megaohms, however the laptop still doesn't power up and also multiple components(inductors, caps after the shorted mosfet still read 3 ohms. Does this mean the dedicated GPU is dead? As it got the full 19v momentarily. Is there anyway to disconnect this GPU and use the iGPU?
Thanks!
Why are only repair 19V short circuit?
Very good ❤
regardless these are still interesting and there is something to learn for some of us. Thanks
i see that you say that the reading is not good, but what is the reference?
did you take electronics in school/college/uni? or just kinda on your own as you went?
I've been working in computer repair shops for nearly 20years, but for board level stuff, I watched a lot of Louis Rossman on TH-cam back in 2016-ish
@@Adamant_IT ah neat. yeah, i've only watched LR (and now you! also a little bit of Northridge) when it comes to my electronics knowlege. oh, and also Buildzoid (mmmm tasty tasty VRMs).
it was enough to give me the confidence to attempt repairing a PS3 Rock Band III guitar which has 1-2 caps that go bad. well, 2 guitars. i fixed *one* of them 😅. wondering how deep i want to go with electronics considering i'm over 40 😬
Gnarley goop.
(15:44) Just after plugging in the 19Vdc adapter I thought I saw a momentary "spark" just above the black cloth a few centimeters away above the second fan and thought I'd check there.
On the other hand, I would have replaced, in addition to the damaged Mosfet, also the other four (in case they were connected in parallel) in that area with substitutes from a manufacturer recognized for their reliability (better quality) and they are not expensive. If doing that doesn't fix the fault, then I stop the repair:
AON6962 (Alpha & Omega Semic) = SH8KC6TB1 (ROHM Semic) $1.27 bucks each piece at mouser. All the best.
yeh about the 2 o clock of the right hand fan !
guy you did your best !
nice one, would be great if you had explained how to find a main rail 👍
I'm working on some new tutorial videos for this right now, they should be done in the next week or so!
I don't know about 5 ohm being a short. I've seen Vcore on CPUs at 11 ohm, and GPUs get down around 1 ohm in normal operation.
I would still like to see a IPA single point hot spot. Normal running it's usually the whole die that gets hot, ie, not a single point.
In telecom cabling thats a heavy wire to wire -really bad but not completely short
What is that chip monk thing, have you done a video on it?
Yes Graham did a review of the whole line of products including the Chipmunk that Harald from CMIZapper offers. It was a couple of months ago.
Quick question:
If the CPU is dead, would replacing it fix the issue?
Most likely yes. And CPU replacements are absolutely possible, but the time/skill/equipment/parts needed to do it usually make the job uneconomic. Much easier to replace the mobo/laptop at this point.
When you replaced that chip I noticed it was the other way round compared to the one next to it, does that make a difference, I'm just guessing?
It was a coil. The orientation dont make a difference
@@thorstenbanholzer4910 Ah ty, I was just guessing anyway, I've seen some where they have to be the right way round that's all.
I fixed the chargers with a 19 v battery drill, using it as a generator. The chargers started to work again. The method didn’t work with usb chargers. Chargers are often disabled by the default battery manager installed by the manufacturers. Gamers must uninstall this software, if the laptop can hibernate properly. Hibernation is needed, or else other malfunctions may happen. Some office work or copying and viewing doc xls files can enhance the performance, and only needs to be done once.
Can't fix them all Graham!
Film everything! Its all content and youtube is lacking in board repair stuff
Similar repair with similar Acer laptop: th-cam.com/video/bGK5Xn2zXUk/w-d-xo.html
@@TheSpotify95 Agreed.. seems a pity they don't add a crowbar circuit to protect the CPU.
You wouldn't catch me owning a laptop with SMD CPUs if I can help it. If it's not socketed forget it. I have older stuff that I know I can fix unless it's not worth the cost of repairs. When possible I'll upgrade older stuff before I buy some of this new junk, as I've always got a OS for it.
soldered dead CPU = economically irreparable
If you hadn't swapped parts for the video. What would you have done instead? If the customer doesn't want the laptop would you hold onto it for parts or would take it somewhere to e-cycle it?
Yea next step is to see if a replacement mobo can be found, failing that, donor laptop for parts.
Need your tech help please. My friend bought an Asus ROG Strix B550 m/board and a Ryzen 5 5600g CPU. Everything was fully working with the m/board UNTIL he decided to plug in the 4x pin 12v power cable (next to the 8x pin 12v power socket) and his m/board went "Pop" with a little bit of smoke. I've tested his CPU on my AM4 m/board and that's fully working still but although his m/boards logo lights up, when i try and power on his board, all i get is a quick "Click" sound and nothing. The board totally refuses to power on. Without doubt a component or maybe more will have blown on his m/board somewhere along the 4x pin 12v power rail. Is there a way i can contact you direct (off this channel) in order for me to fault find which component/components will need replaced on his board please, bud ?
Interesting... not sure what caused that to happen. But yea, definitely sounds like a short at the EPS inputs. I would put a multimeter across the EPS pins (one of the top-row pins to one of the bottom row pins) and see if the resistance is 0.
If it's shorted (low resistance) then a capacitor or similar has died (if you're really unlucky, a power stage) if it's high resistance, my guess is a fuse has blown open. But I think the board would still turn on (but not post) if there was a blown fuse on the EPS rail.
Best way to talk to me directly is through the Discord server realistically, it's one of the few places I'm consistently active/paying attention.
Wow good one.
What temperature do you use in you heat gun?
Usually 400c, pushing a bit higher to 420 if I need it. I've recently made a bigger point of 'wetting' joints with fresh solder and the soldering iron first though, as it really makes components easier to shift the first time.
@@Adamant_IT Thanks!
It's never the cpu, unless it is.
Re: "Unlocking the LATENT POWER of my old graphics cards (April Fools 23)":
it turns out, that particular Corsori brand of air fryer is under factory recall, (no joke) due to some kind of "fire hazard" recently found with the internal wiring. It might be interesting to dis-assemble & inspect (and potentially repair). Corsori has notified Amazon purchasers to sever the power cord and take photos to prove that was done, before they then ship out a free replacement.
what would be a normal resistance on main power rail?
10's of kiloohms or 1-2 megaohms, which you see depends on the laptop of course.
From my experience if you see something between 100 and 1k that's usually bad capacitors on the line, of course not a dead shorted capacitor just a faulty one.
When i see a low resistance like the one the video i just check continuity from the main power rail to one of the vcore coils or any secondary power supply coil, if it gives a low reading i know i have a shorted high side MOSFET.
@@miguelfontenele221 but don't cpus and gpus have inherintly low resistance? Or is it just on vcore rail? Also what is too low of resistance on vcor and can it even be used as an indication of cpu short if you don't have a known good to compare with?
@@starlino They do have low resistance but when the laptop is off the high side MOSFET does not conduct, therefore it isolates de main power rail from the other rails. So yeah, vcore and gpucore should read low resistance only in their rails specifically.
Now for the other question, modern cpus have very low resistance especially gpus so you can't really differentiate a short from a healthy one with just a multimeter. On older chips the resistances are a bit higher, like 5-10 ohms on vcore and a bit higher than that on system agent rail.
I usually check if the buck converter components are ok, if they are i try turning the machine on and diagnose from there, but yeah, i don't really know if it's possible to check if those chips are good just from resistance measurements alone.
Why didn’t you programme the bios just incase.
@@TheSpotify95 i know i actually work in a shop and do repairs myself. Naturally you will get a low resistance to ground.
Fan spin for a sec or 2 after power on , and then stop is actually of on the known sighs of a dead CPU/GPU
One more thing, very low resistance under 1 ohm is actually a good thing, it mean probably dead CAP and not CPU
Genuine question: Would it be possible to replace the dead cpu? If so im curious from a business perspective why you wouldn't want to try it
Possible? Yes. Economical? no. The equipment needed to desolder and resolder a CPU of that size, is not trivial, and it's not always successful either. There's a high risk of failure, which makes it uneconomical to even attempt, compared to just replacing it with a working board.
The cod3r has a video of replacing an APU on a PS4, which is a very similar process, and it can show you what is involved. Just search youtube for "I Couldn't Let TronicsFix BEAT ME So I Replaced His APU! But Did It Work?", and you'll find his video.
Usually I have heard that if the cpu is soldered to the board it can't be replaced. What I always wonder is if it is possible to get another board for a gaming laptop or if the cost is so high the customer is better off buying a new laptop.
New MB realistically, in the interests of lessening e-waste you wonder why they don't socket them as they used to.
Possible? Yes. But a proper CPU replacement requires a decent setup. Some people do it with preheater and hot air, but that's hit and miss. A proper replacement would require a decent rework station which will cost you a couple thousand bucks in itself. Then there's the problem of replacement parts, neither Intel nor AMD will sell CPUs to just anyone, so all the replacement parts you can get are desoldered from boards and reballed, so there is no certainty that the part you buy (which will cost you between 50-100 bucks usually) even works. In general, for most machines, it's just not economically viable.
Is it possible to change the cpu in that laptop?
Theoretically yes, but it's not practical. The equipment and skill to do it is very high level, and you need to have a known-good replacement CPU too.
Is it worth making a CPU swap in the case of this laptop?
You usually don't want to do CPU swaps. It takes more than just swapping the CPU, and tends to create heat problems (if it has higher TDP)
As soon as you said "acer nitro" I said suckface, took me ages to think I'd heard it from Dawid.
Which company makes the least reliable gaming laptops, please answer
Can't win them all. Seems odd (to me) that the main rail was 5.7 Ohms (with a shorted mosfet), 1.8 when the mosfet was replaced, then partially attempted to power up (with a missing mosfet). May have been worth rechecking the main rail, other voltages etc.
The lower resistance after 'replacing' the mosfet was due to heat in the CPU, the resistance would've gone back up to 5.7 if I'd given it more time to cool.
Yeah, that's Acer.
Watching the video on this exact model of laptop. Don't know if that's a good thing lol
If you have a computer repair shop near to you, consider showing them and asking if they have a small heatsink to put on that nekkid mosfet so it doesn't blow itself up when you game / consume power and heat it up - it sounds MacGyver-ish but it's not a big deal, it can be setup so that the case when it's closed it keeps it in place. It seems like a design flaw either due to lack of attention or on purpose, could be either, but it's very stupid and bad and kills an entire system. It just seems easily avoidable.
Every. Last one. Of these gaming laptops with a main rail short on the CPU I've seen have had Ryzen CPU's. Absolutely horrible.
You think they are sabotaging AMD laptops? In the past years the cooling solutions were awful and even the air-supply through the case was too closed to work, like purposefully/intentional design flaws. And it was the same on Asus and other manufacturer's laptops but only on models with AMD chips.
planned obsolescence. IN THE OLD DAYS YOU COULD JUST CHANGE THE CPU ON ANY NOTEBOOK!!!
nice
That mosfet is an intentional time bomb. Anyways, I wantch a guy from Russia who can swap that CPU in no time.
true, because i have motherboard dead CPU, Vcore 5,2 Ohm
👍
shame about the laptop. But on a side note since it is a *GAMING LAPTOP* I would let your clients of future gaming laptops know that they could get up to 30% more performance if another memory module was installed in the vacant slot for dual channel mode. The extra memory bandwidth will make a big difference.
I mean you already have the laptop open up anyway, It wouldnt be such a bad idea to shoot the idea across to them and see what he/she thinks. 30% is still quite a hefty chunk in terms of performance.
as always. love watching you work!
I always wonder if he asks the customer if he wants to install a second memory card since he already has the laptop open anyway.
@@piman2boek364 I always ask anyway because when laptops come in for some sort of repair. Unless its in because of liquid damage or a manufacturing defect. most laptops would have been in use for a fair amount of time so it makes sense to ask. Just a FYI sort of thing. Most are pretty forthcoming and will take the upgrade if you arent trying to rip them off or if they already know how to do it themselves and decline the offer.
Worst they can do is say no and by that time you've already got the laptop assembled again and ready for collection. so there is no time wasted anyway.
Ofcourse it will not power up since 19v power rail is shorted.
I like content like this too, so go ahead and make 'em =)
i was not aware that 6 ohm into the vrm was a short (maybe it is, and i am just ignorant) ...
That wasn't said. 6 Ohm on the main power rail is a short. A short through the MOSFET to the CPU rail.
Acer did it again :(
Just like before the invention of the TVS diode :(
Just like if it was hard or impossible to install one on the CPU and GPU power lines so this does not happen.
That would do absolutely nothing. DC-in FETs will have closed miliseconds after the MOSFET blew, but that is already too slow. A TVS wouldn't work either.
Yea, this is kinda just the risk we run with CPUs/GPUs that need low voltage high amperage. Their power supplies have to be on a high-voltage line to do that kind of power delivery.
Hey friend I have laptop Sony Vaio I love. Do you help me please let me know. Thank you
you made laugh . Its Totally plastic and it is "stone dead" . small things amuse me .I would say the same but the plastic was ironic
Nice video but i am not convinced if the cpu is dead. It can be other problems too .
Considering a desktop CPU is powered with 1.4 Volts maximum and even that is high, and this CPU was fed a 19 Volts hit, I honestly doubt it was still any good.
can you swap the cpu? put an identical one in
You cannot swap a soldered laptop CPU. Do you remember how on desktop you have 999999 pins? well imagine de-soldering / undoing metal glue and doing that perfectly, then solderding another cpu with metal-glue/solder instead of pins - without breaking the newer CPU. It's not possible, not how it works, it's made to not be swapped. Only solution would be for people to stop buying Acer purposefully/intentionally compromised products or swap the motherboard+cpu. The GPUs are also soldered, please remind yourself how many contacts are behind the CPU/GPU to the board, it's not do-able.
Isn’t there any way to check if the cpu is working or false such as frequency check or power good signal because your diagnose is not enough may be superio or corrupt bios failure gives same symptoms
Smile, at least it's not an Asus so the CPU has some chance of not being damaged.
I'm assuming replacing the CPU and the mosfets would not have solved the issues, correct?
More experienced techs. I’m trying to learn off you and I’m lost from what your saying. Shooooot
Apparently Acer went the Apple route with this idiotic design flaw. I'd hope it was not done on purpose, but I would not be surprised if it was. No one associates Acer with quality, this isn't helping them in regards to that statement.
well being Chinese they copied apple's design. China have never created their own designs .
do new CPU
You do know these are not socketed, right? The ones socketed have 99999 pins under them, how the heck do you desolder the contacts of a fragile laptop CPU and even install a different one without breaking it in the process...
Don't buy a laptop with gpu, gpu is the main enemy of laptop. If you need gpu, buy a desktop instead,
^ yup. All of them overheat and require you to use headphones to be able to handle the noise. I would add don't buy an Acer laptop, as it seems they made a design flaw on purpose, cool all the VRM except this one in particular so that it burns out, don't add resistors to keep it under control either.