MacBook Pro Doesn't Charge, Looking at MagSafe
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- Опубліковано 4 жов 2024
- CMIZapper - MagSafe Video: • Understanding the magi...
Working theory about this one is an issue with the SMC's OneWire line. I should've looked at the U7000 area, which is the chip that goes between the SMC and adaptor. However, given that a fake charger gives a green light, it seems unlikely that there's a problem with U7000. The next step back is the SMC itself having a busted OneWire line.
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Working theory about this one is an issue with the SMC's OneWire line. I should've looked at the U7000 area, which is the chip that goes between the SMC and adaptor. However, given that a fake charger gives a green light, it seems unlikely that there's a problem with U7000. The next step back is the SMC itself having a busted OneWire line.
Purists will moan you haven't fixed the problem but in the real world investing more time when another solution does the job is ridiculous. 👍. Met this all the time as a Business Analyst when someone wanted THEIR solution when a simpler and cheaper solution was available. USERs eh! 😂
@@peterlennon1139 -- it's particularly fun when a BA identifies a non-technical solution exists which solves the problem for free. But I'm WAAAAYYYYY off topic now!
To be honest, this "solution" would not feel good to me and I would actually call this a no-fix.
The original charger does turn on (as seen by the green flash --> even PP3V42 comes up, the SMC boots and so on) but then detects some fault-condition and switches off again.
The fake charger doesn't care about that condition and just keeps delivering power.
I get the argument: "If it does work, why fix it?"
But my counter argument would be: That fuse did blow and it will not likely be a coincidence, that that fuse worked for 8 years and now died. It will likely die again in the next days/weeks/months. There is still something wrong with the laptop. Maybe it's just the non-genuine SSD, pulling too much current on startup.
If the plan is to keep the laptop running for a couple more months and not spend more money than necessary, so be it.
You should investigate why you got Mohms to ground after the fuse and a bit later it reset itself to 67k. Does the 67k resistor directly go to ground or maybe through some transistor which can block its path to ground and therefore prevent the genuine charger to turn on. It resets after a while because a capacitor drains or so. Measuring different resistance at different times is HIGHLY suspicious.
The onewire line doesn’t actually go to the charger. It only goes to the plug of the charger where the mac reads details about the charger and it switches the little light red or green.
- Measuring high resistance to ground on PPDCIN_G3H just after unplugging the DC-in connector is expected as the power rail is still charged.
- The zener diode at D7010 is part of the bias circuit for the transistor, as it is a P-channel MOSFET it needs a negative Vgs to turn on, so when the voltage is below 6.8V the zener doesn't pass any current so Vgs stays at 0V. But when the voltage is above 6.8V (i.e., the power brick got out of "sleep"), the zener diode starts passing current and the voltage is effectively clamped to 6.8V as it is dropped through R7010, and therefore the voltage on the gate of the MOSFET is lower than the source (relative to ground, so negative Vgs) so the MOSFET can turn on.
- 1-Wire circuit is unrelated to the problem at hand, even with a blown 1-Wire circuit the Apple power brick would still deliver 14V-20V, but of course there would be no green light. Also since the non-genuine power brick has green light and charges the battery, the 1-Wire circuit is most likely working fine.
- Working only with non-genuine AC power brick is also typical of a DC-in MOSFET problem (as @cadan8258 also pointed out in the comments). It can be a leaky MOSFET (most common), but also something wrong with the gate drive, like the resistors or even the charger IC.
- The DC-in MOSFET issue might also explain why the fuse blew, the DC-in MOSFETs also act as an inrush current limiter and a reverse discharge protection, so something wrong there might overstress the fuse.
- As a side note, the 820-4924 board won't turn on from a non-genuine Apple Magsafe2 power brick (or rather cable, since it's the 1-Wire IC in the tip that causes this specific issue) if the battery is not plugged in or dead.
There are some random info about the Magsafe "sleep" behaviour on LogiWiki, page is titled "Magsafe Sleep Mode".
Issue is likely Q7180. Well known for leakage from a defective in rush limiter. It interferes with the charger load detection. Try replacing this chip. Had this issue happen to me a few times now.
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.
Thank you for sharing this kind of things
Inrush current too high when the genuine charger powers up, and it probably has an internal protection circuit that shut it down, while the "fake" usb charger have a higher current rating (or is more tolerant to overcurrent) and is not affected. That would also explain the blown fuse.
Would be usefull to have a current probe hooked to a scope to check that.
Just to let you know, iron heat applied to a single solder join of any MLCC will or can cause undetected cracks inside the ceramic capacitor and lead to short circuit after a while operating because of DC voltage on it forcing ionic movement along the crack until low ohmig bridge happens!
I've used a few YT vids for Macbook repairs but Paul Daniels and Louis Rossmann have been my go to more often than not. I avoid anything Apple nowadays as parts are often difficult to get unless you buy a donor board and repairability has got worse and worse over a 20 year period. I love working on the old imacs though, they're great to fault find and repair once you get into them.
Good to see u Grahm!
Thank you for sharing ! Very interesting
My 2012 Macbook Pro does the same thing; works on Magsafe to USB C but not on real Magsafe. Thanks for the look in to it.
My theory is that resistor is not connected directly to the ground plane. It was easy to solder that one and after laptop connected to power will create bigger resistance than 68k resistor what we can see on video megaohms . This is only way you can make bigger resistance is to disconnect that resistor from ground plane 😊 so laptop will bring green light recon that something is nok and disconnect resistor, after discharge it will come back to low resistance. Newer repaired single laptop board but this one seams legit for me. And yes on drawing it was direct connection to ground. And yes I love your video and my wife hates your face hair 😂 I love it as well ❤😅😂 nice job
Your wife hates his face hair😂😂😂
thank you very intersting on how it all works thanks again
I wonder if in future it’s worth checking the voltage that at the pin and compare it to what it should be. May be able to change the value of the resistor to create the desired voltage. I think it’s supposed to be 1.8v or something, can’t remember.
Thank you.
worth checking that zener for short?
I'm surprised that you didn't suspect about C7012 or D7010, especially the capacitor, any reason to not check those? I cant see any other part of the circuit giving that kind of problem, but im a newbie to that kind of repairs
Did you check the fuse again after using a charger? Great videos Graham!
Inrush or actual current is too high and shutting off the genuine charger. Also somewhat supported by the genuine flashing the green light, then shutting off.
This also blew a fuse and fuses don't just fail, so something is going on. (obviously)
Too late now, but a suggestion would have been to measure the overall current (when the fuse disappeared during resistor replacement, ho, ho) and compare that with another MacBook, if you have one. I know nothing about MacBooks or anything else really but the SSD comment piqued my interest. Pure guesswork on my part but perhaps the original charger may not have enough wattage for any extras (Apple chargers seem to very finicky in this regard).
What about if it charges when it is powered down, but wont charge properly when booted up? The Magsafe just shows a flickering green light and it doesnt appear to charge.....? :-) I've got one of these as well, one of the 2.9Ghz I5 Dual Core ones.....
maybe there is an issue within the geniune charger ?!!!!!
34:30 it aint 200mOhm its 200ohm but anyways it's well within a spec
new battery old one is pooched ive had the sAME PROBLEM ON OLD MACS IF YOU HOLD THE POWER ON while plugging in mag safe it will boot
Come on now! Apple fuses don't, just break down! They're Apple fuses! Come on Graham!!! Lmbo
Nice video Graham.
What microscope do you use? Thank you very much!
You said that the genuine charger looks for that 68K ohms, did you check the connection where the charger plugs in to see if the charger is seeing 68K ohms. It could be a dodgy conector on the laptop, or trace to the connector, maybe even a dry joint
Hi, do you also carry out revisions or repairs of motherboards on commission?
Hi thx for video I have a MacBook 16’ 2023 I let him in sleep mode some days after I want to charge it that not work no light in MagSafe and nothing happens u think the problem is the battery or something else ? Thx for your answer
Will the genuine charger stop if the resistance is too high, maybe the charging port is adding resistance?
Can you put the link for bought the HDMI test ? Thanks
Your accent is distinctively more pleasant in this video. Thanks for sharing.
I clean my MacBook at ultrasonic, after that he get so slow....
I hope can make videos and teach us what can be the problem ❤
Some sensor problem.
@@worroSfOretsevraH thank you for your reply i hope you can be more detailed
Appreciate
How do I get boardview files
Were you get the schematic?
www.google.com/search?q=820-4924+schematic
(This isn't sarcasm... literally the top hit on google)
Technicians use chipmunks to test laptops?
Have you tried a different genuine charger to check if there is an issue with the charger?
Yea, charger is a known-good. I suppose I should've mentioned that, but yes, always check the charger before you take things apart 😅
Judgeing from the look of the wires at the charger ware it connects to the laptop I think the charger is at fault if the Aftermarket charger is working and the OEM charger isn't that is a no brainer it is the OEM charger .
so triggered by your lack of si prefix understanding. nooooo not milliohms... 68kOhms-67.5kOhms != milliohms!!!
Not only that, 67.5kohm, is within the 1% spec listed 68k *.01=> +/- 680ohms, or 67320-68680ohms. (before you even consider accuracy of your meter... )
yea I was looking at the decimal point and thinking in fractions 😅
Contact Louis Rossman in New York USA. I know of no-one else who may know more than he will. Good Luck.
Louis moved out of NYC 2 years ago. He is in Austin TX now.