Macbook A1502 (820-3476)

[Instafixx]

Machine doesn't turn on.
PPBUS is 12.6V
PP3v42 present.
Fan Spin is there. Takes 500 mAmps.
Just go into Diagnostics or Recovery Mode. Board is clean.

 

[2informaticos]

"Machine doesn't turn on
...........................
Just go into Diagnostics or Recovery Mode"
Not sure how to interpret that.

Do you get CPU core voltage?

 

[Instafixx]

I meant doesn't go into Diagnostics and Recovery Mode.

 

[2informaticos]

If you said doesn't turn on...

However, it turns on, if fan spins.
What about CPU core voltage?
Check U1950 voltages.

 

[Instafixx]

All are 3.4V with random pulsing. Pulses in accordance with Fan Spin

 

[2informaticos]

"Fan Spin is there
.......................
Pulses in accordance with Fan Spin"
Didn't mention any pulse on fan before.
Do you think is good (for you) to waste time, not posting accurate information?

So, power cycling every 5s, or how exactly?
Maybe just 2 pulses...

Did you try SMC bypass mode?

 

[Instafixx]

SMC Bypass didn't work.

Pusling :
First Fan Spin 10 Seconds.
Then Stops for 2 Seconds.
Then it spins continuously for 20 seconds till it starts speeds up and eventually shuts down.

 

[2informaticos]

CPU core voltage and PLT_RESET_L come high, when fan spins?

 

[Instafixx]

L7310/20 is 1.8V
PLT_RESET_L is 3.4V

Tried Re-Balling SMC. Didn't Work

Connected the charger and did a thermal scan.
U3900 gets mildly heated up - around 40 Degrees Celcius.

 

[2informaticos]

I think that's normal; compare with good board.

Try known good BIOS.