820-3787-A no power

[Paky46]

Hi, I have a 820-3787-A board that won't turn on
the customer tried to replace the battery but he mounted the flat j9510 upside down
I tried to do some measurements and the row of capacitors c9321 c9322 etc sometimes sounds short to me but not always. Green and orange light with fans stopped

 

[2informaticos]

Very likely dead PCH.
It got 5V on some data lines probably...

BTW, allow 10-15s since the power is removed, before checking in ohm scale, or diode mode.

 

[Paky46]

but with pch disconnected shouldn't it turn on?
what other measurements can i do?

 

[2informaticos]

How, if PCH controls power on sequence???

 

[Paky46]

I tried with a pch taken from another mac but same problem. as soon as I press the power button the right fan spins for a second and then stops and does not turn on

 

[2informaticos]

"Green and orange light with fans stopped"
You didn't say to get fans spin before.

Check voltage on big coils, when the fans spin.

 

[Paky46]

I said that badly
sometimes not always if I press the power button the right fan starts spinning for less than a second
but it doesn't turn all the time it just hints at turning

 

[2informaticos]

Check if turns on in SMC bypass mode.

You should catch pulse on some big coils; did you try?
Also test the board alone on the desk; nothing connected, no RIO board, no trackpad, nor LCD.

 

[Paky46]

smc nothing does not turn on
all big coli give me 0, a few salt for half a second but then it goes back to 0
only L7130 stays steadily at 12.5

 

[2informaticos]

"a few salt for half a second"
Yeah, but which coils?
Check if ALL_SYS_PWRGD pulses at same time.