Hello All,
I want to thank all for submitting valuable information in this forum.
So, at year end i want to share one of my experiences.
My name is Gerard, 68 years old
and repairing mostly Macbooks on a daily basis. It is a hobby i enjoy very much. Most of the repairs come from shops however.
Yesterday i started with this 820-00850. It would not start after being in the carport for one night with high humidity wheather.
The board was very clean and there was absolute no corrosion or other damage. ( I was not the first one to look at it)
I found it had 20V on USB-C meter with fluctuation amps between 40 and 80 milliamps. This fluctuation came back on several places on the board. Even around the cpu although only millivolts.
Checking the CD3215's i found that one of them did not show 1.1 volt. If voltage was connected to another CD3215 the voltage of USBC_TB_CC2 was fluctuating between 0.4 and 2.6 volts.
So i replaced the bad CD3215.
The board was booting ok. Put it in the chassis and it powered on. Could boot up and test everything. After 30 minutes i shut it down. After a new succesfull boot the fans started spinning at full speed. I let it run for a while and suddenly the fans stopped but the laptop kept running.
Don't see this behaviour so often.
After i shut it down, it would never start again.
So a new repair started.
First i checked the cd3215's because i saw same behaviour as at the beginning. 20V with fluctuating small current.
Then i started measuring.
I used the 820-01598 power-on sequence scheme.
All was ok until i came at the NAND voltages. Input was ok. (voltages, SSD_PMU_Reset_L 1,8V , PMU_SYS_Alive 1,4V.
There was no output from U9000.
As this area was pristine i decided to reflow U9000 first.
During the reflow i noticed there came some crap from underneath it.
After cleaning and cooling down the board is running flawlessly now.
Very happy with it.
Now i came to the conclusion that U9000 really was the culprit.
After replacement of the cd3215 it had been hot and would work for a while.
That might lead to the conclusion that this board can boot and run and have 20V with a faulty CD3215 when its not the master.
So i hope there will be, somewhere in the future, someone that will benefit from this little story.
Wish you all a happy xmas and a very good 2023.
I want to thank all for submitting valuable information in this forum.
So, at year end i want to share one of my experiences.
My name is Gerard, 68 years old
and repairing mostly Macbooks on a daily basis. It is a hobby i enjoy very much. Most of the repairs come from shops however.Yesterday i started with this 820-00850. It would not start after being in the carport for one night with high humidity wheather.
The board was very clean and there was absolute no corrosion or other damage. ( I was not the first one to look at it)
I found it had 20V on USB-C meter with fluctuation amps between 40 and 80 milliamps. This fluctuation came back on several places on the board. Even around the cpu although only millivolts.
Checking the CD3215's i found that one of them did not show 1.1 volt. If voltage was connected to another CD3215 the voltage of USBC_TB_CC2 was fluctuating between 0.4 and 2.6 volts.
So i replaced the bad CD3215.
The board was booting ok. Put it in the chassis and it powered on. Could boot up and test everything. After 30 minutes i shut it down. After a new succesfull boot the fans started spinning at full speed. I let it run for a while and suddenly the fans stopped but the laptop kept running.
Don't see this behaviour so often.
After i shut it down, it would never start again.
So a new repair started.
First i checked the cd3215's because i saw same behaviour as at the beginning. 20V with fluctuating small current.
Then i started measuring.
I used the 820-01598 power-on sequence scheme.
All was ok until i came at the NAND voltages. Input was ok. (voltages, SSD_PMU_Reset_L 1,8V , PMU_SYS_Alive 1,4V.
There was no output from U9000.
As this area was pristine i decided to reflow U9000 first.
During the reflow i noticed there came some crap from underneath it.
After cleaning and cooling down the board is running flawlessly now.
Very happy with it.
Now i came to the conclusion that U9000 really was the culprit.
After replacement of the cd3215 it had been hot and would work for a while.
That might lead to the conclusion that this board can boot and run and have 20V with a faulty CD3215 when its not the master.
So i hope there will be, somewhere in the future, someone that will benefit from this little story.
Wish you all a happy xmas and a very good 2023.
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