820-00045 a1534 wont turn on at all, not water damaged

ielectron

New member
What are the troubleshooting steps for this one if it wont power on?

I took out the board, checked under scope, literally no water anywhere, no dents on the housing, so it seems laptop was properly used.

The small white LED is on when i connect the charger (i have an original apple charger usb-c), i can measure 8V on the battery connector when they are connected.

Fixed this model few times with new keyboard and new screen, but never measured the board before.

So what measurement will i report to you?
 

ielectron

New member
also, i did not find donor board on aliexpress, only working boards for like 385eur (this is a 1.2ghz, 512gb ssd, 8gb ram model)
 

larossmann

Administrator
Staff member
Measure the power rails with the charger connected, battery disconnected. Which are present, which are missing?

I would start with PP3V3R3V0_AON. Is this present? If not, what is its resistance to ground? If resistance to ground is below 350 ohms, does removing U4700 remove the short circuit?
 

ielectron

New member
I came back finally to this one no shorts on any rails
PP5V_S0 = 0V
line is not shorted to GND
led is glowing a bit but laptop didn't take any current/charge, and doesn't turn on
connected to power supply on battery connectors takes 0,10A nothing heating up.
U7100 replaced
u4700 replaced
no luck still not working
Any ideas ?
 

2informaticos

Administrator
Staff member
U7100 has firmware.
New chip will not work, you need one from donor board (same model).

Do you get voltage on PPBUS_G3H with new chip???
 

ielectron

New member
I have connected power supply to battery connector. Should I put back U7100 ? I have another donor board with have faulty CPU, well CPU only is heating up.
 

2informaticos

Administrator
Staff member
"I have connected power supply to battery connector."
I'm not sure if I correctly understood you...
Did you connect bench power supply to battery connector, why?

You've got 8.6V with original U7100.
Did you change it in base of which reason?
Didn't measure more signals on the board?
 

ielectron

New member
Because is easier to measure both board sides with power supply, would I will getting not right measurements with power supply ?
I replace ic to try maybe it will resolved issue, this was common issue so I tried replace it.
I didn't measure anything more so far.
 

2informaticos

Administrator
Staff member
These new boards will not start untill SMC talks with the charger...
And never change components before some measurment indicates that.
 

ielectron

New member
Problem is that the laptop is not taking charge no current taken, on old or new ic, so SMC is not talks witch charger and this U7100 is responsible for a charging as I can see on schematic
 

ielectron

New member
I put back U7100 from donor board PPBUS_G3H is back to normal 8.6V
laptop still doesn't turn on.
PP5V_S0 =0V
PP5v1_s4w = 0V
P5VOUT_EN = 0V
PP3V3_G3H present
I reflow SMC but no changes.
 

2informaticos

Administrator
Staff member
Post 3V3_S5, PM_SLP_SUS_L, 3V3_SUS, PM_SLP_S5_L, PCH_RSMRST_L.
Check if any pulse at least.

Trigger SMC_ONOFF_L and see if PM_PWRBTN_L reacts.
 

ielectron

New member
I check voltages that you said

3V3_S5 = 0.5v no pulses

PM_SLP_SUS_L 0 = 0v no pules

PM_SLP_S5_L = 3v3 no pulses

PM_RSMRST_L = 0 no pulses

SMC_ONOFF_L = 3v26 going down to 0.3v when power button pressed

PM_PWRBTN_L = 1.22v no changes when pressing power button
 
Last edited:

2informaticos

Administrator
Staff member
"3V3_S5 = 0.5v
-------------
PM_SLP_S5_L = 3v3"
Are you sure?
High level for PM_SLP_S5_L means the board already achieved S5 state and goes to S4; but you are missing a basic S5 voltage!
Check resistance to ground at L7560.
You could have a problem with U7400.
 
Top