I have a MacBook Air 15" 2023 M2 A2941 820-02862 motherboard that won't power on. Initially, a malfunction was detected in U7700, which was replaced, and the diode values returned to normal. However, it's worth noting that the PPBUS_AON line has an abnormal value of 0.075V. I've already replaced U5200, but it continues to behave the same way.
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MacBook Air 15" A2941 820-03160 Stuck 5V 0.009-0.010A
- Thread starter BGTR
- Start date
Which schematic are you using?
"PPBUS_AON line has an abnormal value of 0.075V"
If that is voltage, what is diode mode to ground reading?
Remove battery + charger and wait 15s before checking.
"PPBUS_AON line has an abnormal value of 0.075V"
If that is voltage, what is diode mode to ground reading?
Remove battery + charger and wait 15s before checking.
Guided by A2681 (02536), disconnect F5200 and check C5252 voltage.
It should have a separation fuse for PPBUS_AON.
"The voltage at the PPBUS_AON diode is 0.012V"
I'm not sure what this means.
I always said NEVER write end "V" for diode mode readings; just to avoid a confusion between voltage and diode readings.
If you really have 0.012 in diode mode, that is practically short to ground for PPBUS_AON.
"The voltage at the PPBUS_AON diode is 0.012V"
I'm not sure what this means.
I always said NEVER write end "V" for diode mode readings; just to avoid a confusion between voltage and diode readings.
If you really have 0.012 in diode mode, that is practically short to ground for PPBUS_AON.
Applying voltage without any previous checkings?
Do you have same 0.012 reading on any coil from secondary power supplies derived from PPBUS_AON?
Do you have same 0.012 reading on any coil from secondary power supplies derived from PPBUS_AON?
???
Impossible to have the same readings on ALL secondary coils!
I don't have the correct schematic, but looking at 820-03286, did you really check (corresponding coils) L5800, LC320, LC710, etc?
Impossible to have the same readings on ALL secondary coils!
I don't have the correct schematic, but looking at 820-03286, did you really check (corresponding coils) L5800, LC320, LC710, etc?
Just in case, check at LP800 too.
If no low readings on secondary coils, then is safe to inject voltage on PPBUS_AON.
As always start with just 1V, increasing slowly and looking at the board with thermal camera.
Set amp limit to 3A, should be sufficient; also remove CPU heatsink.
0.012 is not pure short; may need to go up until 5V or more, to detect something on the IR camera.
Inspect audio amplifiers areas first; these are very sensitive to corrosion.
If no low readings on secondary coils, then is safe to inject voltage on PPBUS_AON.
As always start with just 1V, increasing slowly and looking at the board with thermal camera.
Set amp limit to 3A, should be sufficient; also remove CPU heatsink.
0.012 is not pure short; may need to go up until 5V or more, to detect something on the IR camera.
Inspect audio amplifiers areas first; these are very sensitive to corrosion.
Did you look on both sides of the board with thermal camera?
Do you have short to ground on that line?
Try to clean the hole, without damaging inside layers; may be impossible...
Try to clean the hole, without damaging inside layers; may be impossible...