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820-000163 sudden death

S

Shadow

New member
Hi,
I got a macbook from our supplier that was working fine, they said that they truned it off and the next day it didnt work anymore. There is no signs of water damage on the board, when I connect the charger the magsafe LED turns on green then amber and stays like that, there is no signs of shortage anywhere, all power lines that are "always present" according to the schematics are there, PP5V_S5, PP5V_S0, PP3V3_S4 and other are there as well but then all goes to 0v after couple of seconds once magsafe LED turns amber (power lines "always present" are still present) . Anyone have any idea what could be wrong or what could I check next?
Thank you in advance.
 
2informaticos

2informaticos

Administrator
Staff member
Likely bad CPU, caused by (in)famous FDMF6808N chips.
Do you get VCORE in the first seconds at least?
Try to start in SMC bypass and see what happens.
You can try to replace FDMF6808 with (real) new FDMF6708, from Mouser.
 
J

JohnB8812

New member
This doesn't sound like random shutdowns but rather no power...
Voltage on PPBUS_G3H? Post all voltages that you can need numbers. Also using OEM KNOWN GOOD 85 watt magsafe 2?
 
S

Shadow

New member
SMC bypass didnt help - it doesnt do anything, voltages around FDMF6808`s are looking good, the charger im using in the shop is 60w but I assume that the owner have an original charger on which it stopped working, that machine was in other repair shop where they said that there is no way to fix it. Volstages on some of the power lines that I have measured are as follow:

PP3V42_G3H = 3.44v
PP5V_S4 = 5.01v
PP5V_S0 = 5.03v
PPDCIN_G3H = 17.08v
PP3V3_S4 = 3.33v
PPVIN_S5_HS_COMP_ISNS = 12.63v
PPVIN_S5_HS_OTHER5V_ISNS = 12.63v
PPVIN_S5_HS_OTHER3V_ISNS = 12.63v
PPBUS_G3H = 12.63v
PPVCC_S0_CPU = 1.79v
PPVCC_S0_CPU = 1.79v
PPVCORE_GPU = 0.85V
 
J

JohnB8812

New member
There is your problem you MUST have an 85 watt for this board! All your voltages are present which is strange, but this sounds like wrong charger to me.
 
S

Shadow

New member
ok, so I tried to run in on 85w charger and now all the power lines stays on, macbook is turning on but there is no image, no backlight, the magsafe LED goes on green and changes to amber like before, when trying to turn it on with SSD or touchpad connected, it wownt turn on(got it only once to turn on with them connected). I dont know but it looks to me like north bridge have to be reflowed? that would make sense since it broke down after cool off.
 
J

JohnB8812

New member
Ok so this could be many things then. Have you at least tried a new 2015 A1398 display? Do you get 5 volts at the LCD for LCD power?
 
S

Shadow

New member
No I didnt check new display as we dont have any other one in the shop and yes I get 5v for LCD, and since HDMI doesnt give any image I would assume that there is something wrong with RAM or north bridge?
 
J

JohnB8812

New member
Disconnect the internal LCD and try again to see if any external. If you have 5 volts at the LCD, I would assume bad screen.
 
S

Shadow

New member
ok, so it turns out that we have image on LCD and HDMI but need to whait a bit longer for it, I found out that when the machine is cold it runs with touchpad and (I made a mistake in previous post saying SSD) wifi card disconnected otherwise it doesnt start, when the machine is warmed up I can shut it down, connect both touchpad and wifi card and it runs fine. I tried to find out what needs to be warmed up in order to get it running with everything connected by using heat gun and it looks like PCH, unless there is something else around PCH that gets the heat and starts to work.
 
S

Shadow

New member
yeah.. thats what I get all the time on my desk.. it cant be anything simple but always some mistery fault.. :D I think its a faulty PCH, I dont think it could be anything else
 
2informaticos

2informaticos

Administrator
Staff member
Check U2080 area.
How varies PLT_RST_BUF_L on cold and heat state, w/ and w/o above mentioned devices connected?
Compare with PLT_RESET_L level.
 
S

Shadow

New member
Could condition:
Devices connected PLT_RESET_L and
PLT_RST_BUF_L ​
are 0v
Devices disconnection
PLT_RESET_L and ​
PLT_RST_BUF_L ​
are 3.33v

Hot condition:
In both conditions (devices connected and disconnected), both power lines are at 3.33v​
 
2informaticos

2informaticos

Administrator
Staff member
Change U2080.
Seems that one device pull down its output; on cold state.
Check for corrosion on that area.
Strange that PLT_RESET_L goes down too.
 
S

Shadow

New member
No, its not the U2080, connecting WLAN or touchpad in cold state brings PP3V3_S0 down to 0v because PM_SLP_S3_BUF_L is not present, this line is not present because PM_SLP_S3_L is not present because its not being generated by PCH
 
S

Shadow

New member
SMC bypass doesnt work in this condition, if the machine is cold and either touchpad or WLAN is connected then there is nothing you can do with it, its completely dead. There is something that its common to both touchpad and WLAN that PCH doesnt like or the PCH itself is faulty i think
 
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