820 3437, some times turn on some times not

[Noguinfor]

Hey,

working on 820 3437 motherboard, No liquid damage. corrosion and no one touch on this motherboard before me!

i don't replace any component too because i need first your opinion!

This one first time i had in store come with problem no charge and goes off suddenly but i realize that problem is the battery!

in my store i test the mac with other original battery and the machine work's perfectly!

i send to client the machine and he don't replace the battery!

Now the machines some times turn on some times no! When start work's perfectly but when i turn it off and try to turn on again i can see the fan sniping 1 sec and off!

In my opinion this macbook, because shut down suddenly very times corrupted the bios!

can you check this original file if it was working properly??

https://drive.google.com/file/d/1GJytmcqtE4xzGEdv1hEAsNo9Jz8VLqlf/view?usp=sharing

thanks

 

[JohnB8812]

Does the device still work off a known good battery??? This sounds like an issue with the battery if the customer didn't replace it......

 

[Noguinfor]

i have a known good battery here! now, even with a good battery i have the issues i say above!

with only battery or charger or with bought the machine "some times turn on some times no! When start work's perfectly but when i turn it off and try to turn on again i can see the fan sniping 1 sec and off! "

I can see the battery charging with my power supply! With battery the client when i put it on mac the orange light goes to green!

 

[2informaticos]

Run ASD EFI version (when possible).
Set On Error option to Continue, uncheck SSD and Memory tests.
See if any error pops out.

Try to start in SMC bypass mode; when doesn't start in normal mode.

Do all tests w/ and w/o battery connected.

 

[Noguinfor]

this by serial number is early 2014! i think the asd tests only goes to 2013 right ??

tis one it's rare to pass image.. when don't pass image fan continues sniping! i try to start in bypass mode and same history only fan spin!! with or without battery!

you have a bios for this model with clean_me?? i have other bios IC and i can program that to see if the problem is the bios!

thanks

 

[2informaticos]

"i think the asd tests only goes to 2013 right ??"
NO, Apple dropped it since 2015.
3S156 is the right version for your machine.

Does it stay on (fan continue spinning) in SMC bypass?

 

[Noguinfor]

Hey,

This one is fixed! it was not making sense this symptoms!! I double check the board and found R7821 pin 1 with a little corrosion! i replace the R7821 and the machines work's normal!!

Thank you!!!

 

[2informaticos]

That make sense.
R7820/21 divider sets the 1V8_S3 voltage value.
Incorrect voltage blocks the CPU I suppose...