820-3462 no power A1425 retina

MDY

New member
It is A1278 820-3115. Titile is wrong

No liquid damage as I see. It doesnot power. I tried 2 different AC adapter 60W and 85W
Green light is on. When press power button nothing happend.

P3V42G3H_REF3 - 3.29V
PPBUS_G3H - 12.55V
SMC_BC_ACOK - 3.3V
SYS_ONEWIRE - 3.3V
ADAPTER_SENSE - 3.3V
PP3V3_S5_REG - 3.3V
SMC_ONOFF_L - 3V- 0V -3V when press power
PP5V_S3 - missing always before and after power
PM_PWRBTN_L - 3V - 0V - 3V
PM_SLP_S5_L - 0V before and after power
RTC_RESET_L - 3.3V
Seems PCH doesnot respond. What I miss?
 
Last edited:

dukefawks

Administrator
No need to press power button it auto powers on. Hook up the bare board and while connecting the magsafe keep an eye on PP5V_S4 on L7220. Also check all coils for short to GND
 

MDY

New member
Well, when I say press power I mean short to ground smc_onoff_l and I always work with bare board. Yestarday last thing I did was put flux about PCH and heat it, but doesnot work.
Now, I just took the board to test and it power and video is ok. Dont know really what was wrong and if it will fail again very soon. Any idea what to do in this case?
 

MDY

New member
It power 5 times and now it doesnot power. But I noted something intersting. With fake 60w adapter green light is always on. I tried now and 5 times will not power and 1 time will power.
With original 60W adapter when I plug it I can observe 2 thing.
1. If green light is on constantly it will power and will have video
2. If green light is on but blinking, it will not power. It is blinking 90% on and 10% off, but easy to realize it is blinking.

Hope with this you can tell me something more.
 

dukefawks

Administrator
The green light should turn orange even without a battery connected. This must be liquid damage, inspect closely again.
 

MDY

New member
Sorry, I was looking 2 board at time and this one is 820-3115, not retina I said in title.
I found something bwtween pin11 and 12 in U2600. I remove it and reflow it with flux and now it power. Do you think this coudl be the problem? U2600
 

MDY

New member
As I see pin12 is SYSCLK_CLK32K_RTC and PCH need 32khz to respond with S5 and S4. Sound logical to me.
 

dukefawks

Administrator
U2600 is important but has nothing to do with getting a green light or not. Probably also corrosion under SMC.
 

MDY

New member
Now it works always and green light some times dissapear for 2,3 seconds, but laptop keeping on.
 

dukefawks

Administrator
I still say crap under SMC. But try another magsafe board and Check if SMC_BC_ACOK stays high when green light goes off.
 
Top