Analysing MacBook Liquid Damage - LFC
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- Опубликовано: 23 янв 2024
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Thank you Graham. That's one of the best diagnostic videos I've ever seen. Great job. Thanks for hanging in.
On a quick add-on to your explanation about corrosion, yes you are right some of the green thing is from the water but not only the water , that green looking thing is partially copper oxide.
Electrolysis happens also when you dump water on a computer that still gets power, ripping apart some of the thin and copper from the board that then forms the deposit.
I simply love the way you explain things. It makes it so much more understandable for me.
As someone who does a fair bit of fault finding in my work (Locks/Access Control), this is a textbook example of the logical process. Knowledge is easy to acquire, but the application of that knowledge is what makes the difference between an average and an excellent technician. Chapeau, sir! 👍
Thanks! That was an extremely good schematics/circuit explanation. Please have a beer or coffee on me
Graham i swear you would make a fantastic teacher/Professor you make this simple you explain it to ware people don't have to scratch their heads to figure out what you said you don't talk extremely technical like some people do.
You're becoming a real expert for the A1466. Interesting to know how the circuits and the components works on this board. Thanks Graham 🙂
Love the methodical fault finding + explanations Graham, really informative
this becoming one of my favourite repair channels. I just love the explanations (and the time you spend explaining). Thank you Adam. Your videos are greatly appreciated.
Not Adam, Graham.
Thank you for the correction.@@marcellipovsky8222
Awesome demonstration of troubleshooting. Too bad for the owner that their venerable old laptop is kaput.
Great video! 44 minutes felt like 5 minutes.. Hope you get a desktop pc to diagnose sometime soon!
Concluding dead CPU from disabling the RAM power rail buck controller seems like a huge shortcut to me as this will stop the power sequence in the middle of S0 state (before ALL_SYS_PWRGD). While it is true that several cases of pulsing SLP_S4# (which is what I'm pretty sure this is, and not flat out missing) could be attributed to a bad CPU (or PCH which is on the same package here so doesn't make a lot of difference), other things can cause that as well.
It is still not completely clear what can be all the causes, but a very common one is bad communication with the SPI ROM which will cause a pulse on SLP_S4# every couple of seconds. Another one can be a missing analog reference voltage (AVREF) on the SMC which is used for analog sensor readings such as current sensing, in this case I think it's a couple of pulses when plugging Magsafe in and the machine may be able to turn on in SMC bypass mode. Current sensing circuits in general could be a source of problems.
On A1466 it's also common to have corrosion on pin 8 of U1950 which will prevent the SYSPWROK signal from working properly and it is required near the end of the power sequence before PLTRST# is de-asserted.
VCCST_PWRGD circuit can also be of concern.
HSIO power circuit should be checked as well, not sure what the exact symptoms are but it's also often a cause of failure after liquid damage.
A single but slightly longer pulse can be caused by a bad bootstrap circuit in some regulator such as the RAM power rail regulator, I wasted a lot of time on my first A1466 repair with that, the probe point was eaten away and I missed it at first.
And of course since power sequence is stopped early, there could be an issue with one of the later power rail such as CPU VCore.
Sometimes it can also be dirt under the CPU package if there was liquid nearby, I'm not saying reflow CPU (I'll never say that) but flowing some flux (without trying to melt the balls) could help (it can also cause misdiagnosis because you'll be blasting some heat onto the CPU). Dirt under SMC too.
Even some broken resistors/inductors near the CPU/PCH feeding some of minor power rails could be a problem.
Anyway, quite an annoying problem as it's difficult to pinpoint an exact cause of failure, but it's more like "if it looks bad, fix it and hope it solves the problem".
Interesting... I've got this board in my breaker pile still, I'll check it again tomorrow when I'm back and the bench and see if PM_SLP_S4_L is pulsing or not.
I've seen other cases where it comes and goes. It's making me wonder about having an extra DMM setup and soldering a probe wire to PM_SLP_S4_L during diagnostics, so I can watch for activity while probing other signals...
@@Adamant_IT A lot of DMMs aren't fast enough to catch that pulse, so I'd recommend checking with an oscilloscope if unsure. I have an old video that compares the behaviour with a Brymen BM857s (the DMM I typically use), a B&K Precision 390A (my spare DMM I've got the USB interface for) and an oscilloscope.
Also forgot to mention there is a full power sequence for that board on logi wiki, might not be 100% accurate but should still give some good check points for the most part.
20:31 I think you mean Tim Apple, not Steve Jobs 😁
Ah the dreaded IMC :( Shame about that but at least it was a solid bit of video for diagnosing stuff.
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.
Excellent video and explanation of fault. Keep up the good work. Thank You...
Great video, I love how you explain the circuits. I hope to see more similar videos :)
very interesting analysis and approach and that is definitely informative.
Great video. Really informative, unfortunate on the dead IMC though
Great video!
Very interesting again thnx.
This came out at the exact right moment, I had an hour to kill watching something interesting, cheers...
that dust lied to me said it was gonna pay me back that money it owed and then ghosted.
Just one thought on your deductions:
When you found ALL_SYS_PWRGD to be low, you said the CPU Phase 2 issue could not be the root cause.
Here is what I think could be the case:
The mainboard initially tried to power up all the way (S0), but falls over, because the CPU Phase 2 is broken.
Thus it drops back to S5.
Thus ALL_SYS_PWRGD is now low.
Since the CPU Phase 2 area looked by far the nastiest, I would have at least reflowed and measured that area before calling the board a no-fix.
A dead IMC on a board with so much corrosion (but none near memory or memory voltage) would make me scratch my head, even if your deductions according to the troubleshooting guide make sense.
It’s the impurities in water that conduct electricity, pure H2O is not conducive.
It's NEVER the CPU......... Super interesting video.
maybe you can measure before the ohm from cpu coils .. to see if cpu is good... Thanks for sharing your knowledge. and from sharing your troubleshooting greeting from portugal ... ;)
That bit gives us Vcore, but there's actually several power rails going into the CPU for different sections of the chip. In this case, the core is probably fine, it was the memory controller (which is powered by the same rail as RAM/DDR) that was faulty. We could take diode-mode measurements at L7430 (the coil for that rail) but I've just checked and the diode mode reading is normal - so that doesn't show the failure.
23:37 WF : Do we need this? lol
Well seeing as we are in the uk we have plenty of humidity lolol
Hi. Is it possible that the TPS ddr chip from the donor board was also bad ?
Maybe the donor board had the same issue as this one now.
What microscope set up are you using ? It looks great.
I e got a MacBook and a guy that worked on it has set everything up to be remote administrator even my network but I have a question about toshiba laptop does it come with a WiFi network card that plugs into the pci e sloth the small white card and Ali's are there suppose to be to rams cards in or one? Long story I need your help
Really impressed with the depth of knowledge and the commitment to trying to keep these laptops going. My question to you and the readers is are these older non supported ( by latest OS) MacBooks safe to use ? I’ve a couple of decent older MacBooks including my lovely late 2013 15 MacBook Pro but it’s stopped taking the latest os’s…. Not keen on OpenCore type approach… is it a parts bin jobbie or still safe to use ?
Tbh as long as it's using a modern browser it's likely going to be OK. Being a couple of macOS versions out is fine as long as it's getting security updates. Just keep in mind that once a device hits the 10 year marker, that's when any kind of hardware failure is usually instant write-off, so don't be attached to it.
Been running Arch Linux on my 2012 MBAir for more than 7 years now. Zero issues, will stay evergreen (SW-wise) until the HW dies.
I know this is completely unrelated but whom else to ask probably a stupid question. I've built a tower PC, with windows 10 pro on the primary SSD, I want to use my old SSD from my laptop as it's got all my games etc but has the same windows 10 on it installed. If I put it on SATA port 2, would it work as an accessible drive or would it cabbage the computer on boot up?
it's never the cpu... unless it's a macbook xD
Pretty advance diagnose
I'm new in logic board repair, I'm having trouble fixing my MacBook 😪
Is it possible to swap CPU from that donor board?
Theoretically yes, worthwhile no. These logic boards aren't worth enough for the time/equipment it would take.
RIP 😒
Was it really necessary. Replace the logic board.
Why can't you get this de-bug machine, it would make your job a lot easier...
I've heard of people putting dirty boards in a dishwasher and cleaning them up. Do you know of this?
Yup, an Ultrasonic Cleaner is the best tool, but a dishwasher is unironically a valid substitute. Proper drying afterwards is the key. Not sure if dishwashers can shift corrosion effectively though - they likely won't get stuff out from under BGA chips.
ultrasonic vybration is the key to get under BGA without rework
Sorry, but I cannot understand wallowing through filth like that, the board needs to be cleaned and thoroughly examined for damage first. I do enjoy your videos, thanks.
can't you repalce the CPU ?
Why are so many techs afraid to replace CPU Chips ????????
Because a refurb board is £100 on eBay if you keep an eye out. Fun fact, I bought a whole ass A1466 laptop for about £150 to replace the board in this one, so I ended up with a spare chassis+screen as well.
Can definitely agree that learning to do CPU work on high-end boards would have value, but on old MacBook Airs... naa.
I appreciate your Reply Thank you very much. Makes sense.
Please more testing and less schematics please.
What areas should I test? How do we know what areas are important? How do we know where to probe and what result to expect from that probe?
please try to make concise video.
What?
are you for real..?
😂please watch the full video first 😂😂😂
Settings -> Playback Speed -> 2
Hope this helps