(347) 552-2258 [email protected]

A2159, no power cpu hot, no fan spin.

K

Kgrou

New member
Hello,

i have an a2159 that had some corrosion.
I cleaned all the corrosion (there wasn’t a lot).
But the computer won’t boot (and isn’t recognised in dfu). When the charger is plugged the cpu is getting hot.
PPBUS_G3H, PP5V_G3S, PP3V3, are all present and correct.

All seems to be clean, so I’m not sure about how to troubleshoot this one.

your help will be really appreciated.
 
K

Kgrou

New member
thanks for your answer,

the board is a 820-01598-06.
L7410 is 0V
L7702 is 0V
L7420 is 0v
L7210 is 0v
L7220 is 0v
L7270 is 0.8v
L8102 is 0.95v
 
K

Kgrou

New member
near C8411, C8468, J3810,R8507, R5335, J5110 (30,26,24), C6900, L8410. All the corrosion affects only one component or a really really small area.
 
2informaticos

2informaticos

Administrator
Staff member
Did you check if all affected components have correct value?
Also be sure to have good solders and traces.
 
K

Kgrou

New member
Yes, all seems to be fine... Maybe I did wrong measurements, that could be possible. But I don't think.
I found that the cpu get hot for 2 minutes and then stop getting hot.
For the solder and traces I'm sure, there insnt anything bad (visible). Should I inject some voltage or is it a bad idea?
CPUCORE_SW1 is not present.
Could u7100 be bad?
CPUCORE_FCCM goes 5v and about 30s later goes 0v.
 
Last edited:
2informaticos

2informaticos

Administrator
Staff member
Inject voltage where?
You didn't report any short.

Do you get voltage at L8100?
Also check for voltage at the coils around U7800 and the switches from page 74.

Just in case, try to put the machine in DFU mode.
 
K

Kgrou

New member
I won't inject voltage, I was wondering I any short was possible.

L8100 is 1.2V
P1V_PRIM_SW.. is 0V from U7800, PPVPCORE 0V. Meaning that U7800 is bad?
U8213 is not on the board, I assume this is normal.
U8290 only have PP3V3_G3H_RTC
U8207/8 have nothing.
The rest Is ok
I'll try dfu mode tomorrow.
 
K

Kgrou

New member
After some research, the MacBook is able to get in dfu mode, and complete the step 4. But I can't have any image, on the screen or on an hdmi adapter. I've tried a different lcd flex and the problem is still the same. Even with an other screen that is the same. What could be bad ? is it a dead gpu?
 
K

Kgrou

New member
L7410 is 0v
L7420 0v
L7210 0.8v
L7220 0.8v
sometimes L7220 and L7210 are 0v.
VCORE 1 and 2 are 5V
fan spins now
 
Last edited:
2informaticos

2informaticos

Administrator
Staff member
When the fan spins, check for USB activity.
L7210/20 must have voltage and you should detect some changes on the voltage value.
 
K

Kgrou

New member
After doing some measurements with the multimeter I don't get anything, no usb c activity (no power), no voltage on L7210/20... but I'm still able to enter dfu mode and complete it. Even when fan spins I can't have any of L7210/20 or usb...
VCore is still 5v. PPBUS is good.
 
2informaticos

2informaticos

Administrator
Staff member
Usually we use VCORE to name CPU core rail; L7210/20 in this case.
If no voltage there, board cannot boot.

CPU is not needed by DFU; T2 does the trick there.
 
K

Kgrou

New member
Thanks for the information, I wasn't knowing that.
Do U7210/20 needs CPUCORE_FCCM to be ok?
Because CPUCORE_FCCM is 0v.
If that is not the problem, what do they need absolutely to provide voltage? and if they have all the power rails necessary but the board isn't sending anything to cpu does that mean that cpu Is dead? (that would be really frustrating because I actually got 0.8V on big coils last day, keyboard lighted up and when I came back to the machine it was 0V again).
Is RTN_B_CPUCORE beeping on diode mode a problem?
 
2informaticos

2informaticos

Administrator
Staff member
VCORE depends by PCH, CPU and BIOS.
There is not just an enable signal, like in old boards.
Possibly accumulated crap under some BGA chip.
You can try to heat and burn the crap, or pass the board theough ultrasound bath.
 
You must log in or register to reply here.
Top