Thank you for that!
With regards to FlexBV, would you say it's worth the investment just for the solution/checklist?
jkruns
Member
Last Activity: 12-08-2024, 06:16 AM
Joined: 03-08-2024
Location: Amsterdam
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Macbook Pro M1 A2338 - how to test for 20V?
I have a stack of liquid damaged A2338's, most of which don't draw more than 5v and thus won't turn on.
So far I've put back the main boards back after cleaning and repair attempts and connected every single component before testing. This obviously take a huge amount of time.
My question is (maybe not limited to A2338 boards): what's the bare minimum that needs to be connected in order to test if it will draw 20V? Should it draw 20V without the battery connected? -
Yeah, I noticed so I tried Sierra and High Sierra as well but it just wouldn't boot from those on external drives.
Spurred on by your suggestion I tried every single release, none of which worked unitl... Big Sur!
Somehow it booted Big Sur without issue and the installer to the local SSD ran fine. I'm updating to Monterey as we speak.
Thank you, you just saved me a $35 EFI chip and a lot of time!...Leave a comment:
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Not the first time (“no bag entry” error) but after correcting with ntpdate time and date are ok.
[USER="439920"]the Benninger[/USER] already did PRAM reset several times.the BenningerNot the first time (“no bag entry” error) but after correcting with ntpdate time and date are ok.
[USER="439920"]the Benninger[/USER] already did PRAM reset several times....Leave a comment:
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A1706 fails to install OS to any disk
Lectori salutem!
The patient is an A1706 model - 2017 mb pro 13” core i7 16GB 512GB 4-thunderbolt ports
Symptoms:[LIST][*]Boots in recovery mode (Sierra)[*]Internal SSD is visible and can be erased / partitioned[*]Sierra install starts with 6 minutes estimate, but at the end of the countdown fails with “An error occurred while preparing the installation. Try running this application again.”[*]The same happens when I connect an external SSD or a USB-C thumbdrive and try to reinstall Sierra on that drive.[*]Does not boot from external (Sonoma) bootable thumbdrive[*]I... -
As it turns out the battery [I]was[/I] bad. The other three batteries are fine, but they didn't work because I missed a crucial bit of information: the large T5 screw that holds down the board onto the battery pcb does more than connect to ground like I assumed. I tested the other batteries without this screw in place, primarily because I removed the batteries from their chassis.
It's still a mystery to me why the battery failed. My working theory is some component on the battery pcb broke. So far I haven't been able to tell the difference between a working battery and the dead one...Leave a comment:
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It's barely audible, so I'd call it normal fan spin....Leave a comment:
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These issues had already gone away. The only remaining problem is the battery not charging when plugged in or booting from battery only. I'm testing this board with the paired touch id sensor transplanted into a chassis with all 100% tested and working components (display, sound, touch bar, battery, touch pad).
It may be worth mentioning I'm testing this with the board not fully tightened down with all the screws and also without the bottom cover (I do connect all the flex cables every single time I test though). I'm assuming the missing bottom cover will not mess up my test results,...Leave a comment:
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Here's the output of the test on a known good box....Leave a comment:
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Here's what the OS registers about the battery and charging.
Other than "IsCharging" = No I don't know what to make of this....Leave a comment:
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Two more observations.[LIST][*]PPBUS_AON is a touch on the low side (12.02). OBD says 12.4 but on other boards I've seen 12.95V. Maybe nothing.[*]I've read several posts from people who've either installed a new battery or depleted their existing battery over a long time, whose macbooks show the same symptoms. Could it be that the issue is not with the board itself but rather these boards really don't like deeply discharged batteries?[/LIST]- Two more observations.[LIST]
- PPBUS_AON is a touch on the low side (12.02). OBD says 12.4 but on other boards I've seen 12.95V. Maybe nothing.
- I've read
Leave a comment:
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I'd love to practice my hot air skills, but the resistance across source & gate are exactly the same on the other 3 boards.
This suggests the K Ohm value is ok, do you agree?Leave a comment:
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Q5265
Source to drain: 1.8MOhm
Source to gate: 3.9MOhm
Gate to drain: 5.8MOhm
The other boards are in the same ballpark.
Q5270
Source to gate: ~360KOhm
Gate to drain: 2.25MOhm
Source to drain: 2.04MOhm
I also checked Q5230 and Q5240. Both seem fine, resistance gates to drains is consistently in the MOhms range.Leave a comment:
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Resistance across C5260 is 2.91Ohm. The other boards read 2.74 / 2.72 / 2.86 respectively.
Unless the tolerances are really tight, this should be ok, right?Leave a comment:
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Makes sense, but how could I have deduced this from the schematics?
There's a list of Power validation test points included in the schematics, but you would have to know what CSO_N and CSO_P stand for or what they do. How did you figure that out?...Leave a comment:
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I will of course do this asap, but I also really want to understand the logic behind this.
How did you deduce from the schematics capacitor C5260 is where you can measure resistance of the "current sense leg"?
And what should be the total resistance reference value? If I had to guess it would be the sum of the three resistors R5261, R5260, R5262, so 2.005Ohm?Leave a comment:
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I assume the ISL charger IC is U5200, correct? If so, what points or lines should I regard as the start and finish? Start at PPDCIN_USBC_AON? What should be the finish? PPVBAT_AON?...Leave a comment:
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Ah. Thanks for explaining NOSTUFF. At first I thought I might have knocked a resister off the board, until I saw the same omission on the other boards 😄
The I2C line voltages on both pins 2 and 3 stay at 3.22V for a few seconds, then briefly dropping down to as low as 2.45V for about half a second. I've included a little clip of the multimeter readout.
As far as I know, all four batteries I've tested with so far are good. At least they were before something else broke in the laptop they were in (screen / mainboard mostly).
The OS does indeed properly...Leave a comment:
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This may be a dumb question, but what's the story with the contact points on the board where the schematics say there should be a resistor but there isn't any visible smd component at that location?
Case in point R5155 which should be a 10K resistor with a 402 footprint, but there isn't any.
I'm trying to figure out why the battery isn't charging, but so far every measurement seems reasonably within spec. I've looked into the Battery logic connector schematics and measured each component several times. The mosfet at Q5155 sems to play an important role here.
To test this...Leave a comment:
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I searched the schematics for SMBUS, which gave me the battery charger support (schematics below)
I carefully measured all the components in this circuit and compared these values against the reference from OBD.
[ATTACH=JSON]{"data-align":"none","data-size":"full","data-attachmentid":3260203}[/ATTACH]
All but one of the components were well within spec. The thing that was off was the CHGR_EN_MVR_A which whould read OL but instead I measured 2.032V.
R5342 and D5340 both look fine visually, as does the board...Leave a comment:
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