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820-00165 boots once and then gets stuck at 223mA

mbcontrol

mbcontrol

Member
I'm working on a 820-00165-A that came in with water damage. After fixing this the board now behaves as follows:
It starts normally when booting for the first time. After that it always gets stuck at approx. 223mA.
If it has been off for a while, it starts up again normally for one boot process. Then again stuck at 223mA ...

I measured all Power Aliases from page 62 while it stucks at 223mA - they are all good.
Can you give me a tip on how to continue troubleshooting?
 
2informaticos

2informaticos

Administrator
Staff member
Any history available?
Tried PRAM reset?
PLT_RESET_L stays high?

Just in case, try new full BIOS, clean ME.
 
mbcontrol

mbcontrol

Member
PLT_RESET_L is high when the board is up on 500-600mA.
When it stucks at 223mA PLT_RESET_L is low.

History:
Customers story: A glass of water leaked over the Macbook, I immediately tried to remove everything and switched off the Macbook, but the screen only flickered and then the Macbook could not be switched on at all.

When it came in, the logic board had numerous spots on both sides with signs of corrosion, but these were not very strong, We cleaned them with flux and heatgun and the board did get an ultrasonic. I have videos from the board before beginning with work - if it helps i can give an downloadlink or upload a view pictures.

What i did now:
I made a new BIOS with Medusa3 from a Donor with clean ME and PRAM.
And i changed U1900 because it had a bit corrosion before and was only cleaned with flux.
At my first test the board was booting two times like normal up to 500-600mA.
But after this it is now only booting to 223mA every time.
I changed U1900 a second time - just in case the chip is not good - same behavior.
Around U6100, U6101, U1900, Y1905 and J6100 i measured in diode-mode all the values from FlexBV OBData - all seems good.
FYI - i can't see any data transfer on the oszi at the Circuits from the BIOS. They have 3.3v but no data signs.
 
2informaticos

2informaticos

Administrator
Staff member
Check U1950 pins 7 & 3 voltage, when board is stuck.
If get voltage, then check CPU_VCCST_PWRGD and CPU_VR_READY.
 
mbcontrol

mbcontrol

Member
U1950 pin7 = 320mV and pin3 = 350mV (not stable, the value falls continuously during the measurement)
CPU_VCCST_PWRGD = 1,02V
CPU_VR_READY = 1,05V
 
mbcontrol

mbcontrol

Member
I had a look under U1950 - pin8 was corroded - the board boots now !
At the moment there is now a problem with the SSD - questionmark folder. That's new - the SSD was running before.
Could this have something to do with the new BIOS? At the moment there is the new BIOS on board.
 
mbcontrol

mbcontrol

Member
I changed the original BIOS back - the SSD is running now.
Is this behavior normal? Must i Install/Configure the SSD after changing the BIOS?
 
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