[SOLVED]820 2849 no light no mag safe when battery is connected

[EJS]

820 2849 no light no mag safe when battery is connected, as soon as battery is disconnected green light returns. Machine will boot, but only if I plug the battery after magsafe is plugged in. I have 3.42v on PP3V42_G3H...

 

[dukefawks]

3V42 present when battery connected? PPBUS with and without battery? ACOK from U7000 with and without batter?

 

[EJS]

3v42 is present when battery is connected PPBUS 7.38v with batt, and jumps like hell between about 3-6v with out batt. 0v with and without batt on ACOK.

 

[aprendiz]

Check resistance between pin 17/18 and 27/28, also voltage on pin 2 from U7000.......

Do not use comments because we cant see when you post, use replay....

 

[dukefawks]

Some of these 2849 are a bit weird without battery is my experience. The important thing is that you are using an ORIGINAL Apple 85W charger, no 60W and no Chinese garbage!

 

[EJS]

Update, I was measuring on the wrong chip yesterday. U7000 ACOK has 2.32v without batt, and 3.19v with batt.
I have 3.88v on pin 2, 3.4ohms between pins 17/18, and 21.4 ohms between pins 27/28.

 

[aprendiz]

3.88V on pin 2 is wrong, check voltage on pin 3 from d7005 also check R7003, it should be 20 ohm...

 

[EJS]

Pin 3 on d7005 I get 16.77v, pin 1 of r7003 16.77v, pin 2 of r7003 3.8v. I pulled r7003 seemed like it was reading a little low, replaced, same storey.

 

[dukefawks]

There is a 13V voltage drop over R7003. If R7003 measures about 20Ohm then it is either U7000 or C7005 pulling it down. My bet is a dead U7000.

 

[EJS]

Thanks Duke and Aprendiz, it was bad u7000, up and running!!!