We need to read circuits before injecting, other wise we don't learn - LFC
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- เผยแพร่เมื่อ 15 เม.ย. 2024
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To add to the checklist: Check resistance between the different rails in both directions. This is to make sure the resistance is high enough that the current won't flow to ground through another rail. This can happen if more then one component is shorted, for instance a shorted separation diode in combination with a shorted capacitor.
I have seen those jumpers on lots of motherboards, usually they look like an elongated solder blob with no component. I suspect they are to allow you to isolate portions of the power rail to help narrow down where shorts are. You can look those up and you might discover they are in sections of the power rail, and if you clean the solder from one, it will "cut out" the section of the power rail and isolate it, allowing you to narrow down the section with the short.
Another great teaching and troubleshooting video. Thank you so much for your videos.👏👍
Truly a learning experience i should say. Your effort was tremendously appreciated! Thank you!
I've watched the video, now I feel astute. Thanks.
Using the schematic to isolate areas on the board to look at with injection reduces the time it takes to find the problem. Good work and great troubleshooting!
I am not too sure if it has to be so complicated. I understand the idea of being careful. Let'say the main power rail is shorted by the faulty mosfet on the cpu power supply. Someone comes with the voltage and injects 19v killing the CPU completely (lets assume CPU survived the initial fault), Obviously we need to be careful not to do that. But is it not easier to just inject lets say 0.9V 1A into tbe short? If we have dead short and thermal camera we will see something getting hot. Also with 0.9V even if short goes trough cpu or gpu we won't damage anything. This kind of workflow saves time and its safe.
You're assuming that because your injecting 0.9v from a regulated supply that it will always be 0.9v. But this is not always the case. Some parts of the circuit can charge and discharge the current creating voltage spikes. So the voltage can be much higher. What often happens is that the current is flowing (at 0.9v for instance), but the voltage is not high enough for the regulators to work properly, so they don't switch reliably and create random spikes. This is why complex components like IC's and especially CPU's and microprocessors can be damaged by running at a voltage below the normal operating voltage.
I sometimes inject voltage to the power rails after lifting off one side of the inductor from the surface so that the load remains safe from spikes and full current flow into the slicon chips immediately when injecting voltage. Mostly I do this with motherboard having BGA CPU. I lift one side of the inductors of the VCORE sections of the CPU.
Maybe the real voltage injection was the friends we made along the way?
Great work.
Thank you.
I thought it flew into the fifth dimension
XWA202 could be what is known as a "net tie", which is a way to join 2 power/signal rails together in a schematic.
Regards, Christian
XWA202 reminds me of X-Wing Alliance v2.02, that contains Tie Fighters. I'll never forget this relation now... :)
Very educative thank you!😊
Adam, you are the single best teacher when it comes to this. Your probes describe you well. Keep it up - from Australia
His name is Graham😂 Adam is his cousin
You did a wonderful job on this.
"The batery is unplugged." That's probably why it didn't start charging the batery this time :)
Another great video, thanks.
Thank you!
Comprehensive video. Special respect from Iran. 🙂
"It's just a little airborne. It's still good. It's still good." ROFL!!!
You need some good quality hot tweezers I would recommend ATTEN tweezers. I know hot air works most of the time but hot tweezers would cause a lot less heat stress...
Great video!
❤ big thx for sharing your knowledge
Your onboard connection is a way a design/layout tool like Altium to connect (power)lines with different names together. Altium created a virtual component for it named "Net Tie". The same could be done by placing a zero ohm resistor, but that would add to the component count, use value space on the board and could fail due to a crack.
excellent video; learned a sh*t ton
Great work Graham. Thank you
You should use double-sided tape and stick the component on the tape so it doesn't fly away
I caught this one 11 minutes after it was posted. Cool. Thanks for helping us learn with you.
When replacing the capacitor using a soldering iron it's better if the pads are flat. With a little solder on the iron you could tack the right hand end, then solder the left hand end, then finish the right hand joint. Mr. Solderfix taught me this :)
Yes absolutely I do that with all tantalum caps. It is better to do with mostly iron where ever possible to maintain quality of the board as well as the quality of services. I see that, the quality of our service depends on how other technicians are able to identify what we have done in the board during the previous repair.
How many CPUs, APUs, Chipsets did I burn myself before seeing your content? Please, I beg everyone, no one dares to ask me that. Thank you very much Graham for sharing your knowledge with us. All the best.
What is the name of the software you use to view the schematic and where can I buy it?
thnks lot for ur effort to make a check list. but one can be brilliant as he can.no one can cover all the components getting voltage from a specific power sup. i think ur best option is to lower the voltage below 1v and hope for the best. good luck bro.
Why don't you F Off with your BS link and advice
Great job... May I ask what kind of thermal camera do you use in the mobile 😊
Please which schematic software are you using, it looks awesome
If you are refering to the Board view software then it's Flex Boardview
"Some people randomly inject voltage without a short circuit, expecting the problem to just reveal itself".....So funny! Finding blown-up components.... that you actually caused yourself!!
Hello, I know this isn't about the video but I need some help.
I have this MacBook A1181 Mid 2006. It doesn't turn on but it does charge two batteries. It's going to need board level repair. I can do that, but I'm just asking what should I look at or for the diagnostics? Thank you for your time
I've got no experience doing board level work on pre-2010 stuff, so I've no idea where to start there!
That's fine! I just took a shot and asked! Thanks for your time!
A surprising culpred lol.
in theory it will flow to the low resistance short but if that short burns out the next lowest resistance gets hit!
hii, which power supply are you using please
Nice camera you have.. what model is that?
The face and overhead cameras are Insta360 Link, and the microscope is an Andonstar AD407
What's the problem with injecting power into silicon if you keep the voltage below its operating voltage? Injecting 19V into a CPU will of course fry it, but what if it's something like 0.9V? CPUs typically work at higher voltages than that.
This is true. I think the point is that you should take measurements first and get a lay of the board and what state its in.
You can check if your main rail is shorted into the CPU without injecting, and then you may not need to inject at all. This is more intelligent diagnostics than going directly to injection first. Like, if you're trying to start a dead car, maybe check if the battery is actually flat before you start getting out jumper cables.
People with repair experience will probably know all this at first glance, but the message I'm trying to deliver here is that we learn good practise before we're good enough to take all the shortcuts.
Done watching, thank you very much for the informative repair video. I have learned significantly more troubleshooting & repair lessons in this tutorial video and to your other repair videos as well compared to my ENTIRE 4 YEARS OF COLLEGE due to the rotten & outdated standards of education here in the Philippines. 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], Proper method of testing/checking of potentially faulty MOSFETs & ICs/Controller Chips, CPU/GPU/PCH Reballing and BIOS Bin File Editing.
Just inject 0.8 volts with limiting at 2A current.You ll be safe,if the heated area is crowded,use alchohol and inject power again to spot the exact faulty component.YOU NEED A THOUSAND HOURS TO FIND IT WITH SCHEMATICS AND MEASUREMENTS and at the end of the days you will have learned nothing.Anyway i admire your engilsh accent and your patience.
That cap had tall legs 😂
Ukranian cap😅
Question: why not use a milliohm meter to locate the area with the lowest resistance on the rail, and do the injection on that point? I know Voltage-injection is a very powerful tool, but you need to know what you are doing. I always shudder when I see people just blindly grabbing their thermal camera, and start injecting voltage at any point on the rail they measure the short. First locate the area of the short and inject there.
That's great if we go with milliohm meter. I think if we are so close to the section it would be farely, doesn't need voltage injection. To make milliohm meter so effective, we need to isolate other components and sections with higher resistance once we identify the sections with lowest resistance. Otherwise although we find a sections with lowest resistance and then inject power it is going spread all over through the power plane. Also Isolating is another problem, we can isolate section if jumper, Inductor or resistors were connected in series between the sections. However, if they are connected directly through VIA then it is difficult to isolate the sections, we may need to go for cutting the traces to isolate sections. These should be considered I think.
I bet you a packet of cheese curls
CAN I COME OVER FOR LESSONS?
"I'll donate to charity when pigs fly... hahaha... so.. should I write that cheque then sir." Simpsons. That first sus cap looked like a little bloated as well as cracked nfi how it's hanging in there.
Sir mostly I saw only macbook repair in your channel in this year is there away that you post more normal laptop repair
Just not a lot of candidates. I want to keep things varied, but to an extent I've got to work with what comes through the door.
Send him a broken laptop.
@@Adamant_IT As someone who wants to describe repairs technics on logic boards it's easy when you can use schematics, boardview files and FlexBv software to visually demonstrate what has to be done. I prefer when you're working on Macs boards. Thanks Graham 🙂
I watched your video in 2x speed and it felt as though that should be your normal pace of speech.
Hi Adam,
Recently I had a super weird MB problem regarding to Realtek audio system.
I did a BIOS update, upgrade RAM from 2x8 to 2x16, then all the 3.5mm jacks ceased working. With no detection of any 3.5mm plug in.
Today it started bombing me with notification of connection with NOTHING physically plugged. It lasted like 2min and stopped. It's like haunted.
MB is TUF B550M WIFI 2.
Do you have any idea how this might happen?