829-3437 not power up

[Glenn]

Have a 820-3437 logic board that won't power up.
have orange light on magsafe.

ppbus_g3h only give 4,35V
Q7130 pin2 16,58

u7100

1 ) 0v
2 ) 16,26v
3 ) 4.41v
9 ) 0,036v
12 ) 3.39v
13 ) 3.39v
14 ) 3.36v
17) 4.12v
18) 4.12v
15 ) 0.028v
19 ) 5.158v
20 ) 5.163v
26 ) 16.35v
27) 16.59v
28) 16.59v

have no history on it

 

[aprendiz]

Remove F7140 and see if PPBUSS_G3H comes up???

 

[jgraffis]

sounds like buck converter problem between u7100 and q7130. i would check for short to ground on pin7 of Q7130, if no short then change q7130, then u7100. I'm betting U7100 is not working properly.

 

[larossmann]

What's the resistance between pins 17/18 of U7100?

What's the resistance between pins 27/28 of U7100?

What is the resistance of R7105?

Will this work from a charged battery?

 

[Glenn]

What's the resistance between pins 17/18 of U7100? resistance between pins 17/18 is 3,3ohm

What's the resistance between pins 27/28 of U7100? resistance between pins 27/28 is 20,2ohm

What is the resistance of R7105? resistance of R7105 is fuck hole on. after replace with new i have 20.4ohm

Will this work from a charged battery? Will charge the battery and see

q7130 pin 7 is 0.120 in diode mode (im not sure if i measured on right pin, because as i see pin 7 is under the chip but i think that is tecsame pin on the side off it)

 

[dukefawks]

If R7105 was bad U7100 will be dead too. Also R7105 will probably be dead again if you did not change U7100.

 

[Glenn]

Yes it was a hole in r7105 and it was waiving someting around 90 ohm



r7105 still gives 20.40 ohm so i tray to replace u7100 again