Asus K53SV - turn on with battery only

[DeniS182]

Hi,
I have problem with this notebook. It works fine with battery inserted, but not working with DC adapter in. DC jack was bad I must fix it first. Fet's near DC jack are ok. I mean main problem is in charging circuit. I made some measurements on charge IC BQ24740. Now I'm little confused because I don't know if is problem with this IC or before him. I can't find schematic of this board, can you send me it or if you know how to help me..
Thanks.

Measurements on BQ24740 without battery inserted.
1- 0.01V
2- 0.5V
3- 0.4V
4- 0.11V
5- 2.65V
6- 0V
7- 0V
8- 0V
9- 0 V
10- 0V
11- 0V
12- 0V
13-11.48V
14- 0V
15- 0V
16- 0V
17- 0.02V
18- 0.02V
19- 0.02V
20- 0V
21- 0.1V
22- 0V
23- 0V
24- 0V
25- 0V
26- 0V
27- 0V
28- 19V

[BlueMidnight]

Re: Asus K53SV - turn on with battery only

The BQ24740 chip is bad. It's getting power (pin 28) and it knows the AC adapter is plugged in (pin 5). Under those conditions, the internal 3.3V voltage reference source must be turned on (pin 10), but it's not.

If you can't find the motherboard schematic, then it's always a good idea to search for datasheets for the chips themselves. They even have example circuits in those that are usually very close to what you'll find on the actual board.

[polytek]

Re: Asus K53SV - turn on with battery only

pin 13 is active low and in your case is 11.48volt, change your charging ic to get it low.

[DeniS182]

Re: Asus K53SV - turn on with battery only

I changed BQ24740 now I have 3.3V on voltage reference pin 10 and on 13pin is 0V.
But nothing changed. I don't have connected pin 21 (DPMDET) because of I damage pad with desolder wick or this is not the problem, I mean this pin is only dummy pad. I measured two shorts on resistors, but I don't know if these resistors are jumpers or not. Have someone schematic of this laptop?

[DeniS182]

Re: Asus K53SV - turn on with battery only

I have missing components near bq24740.. Have someone schematic or same board to tell me values of these components? I labeled these components with blue dots on photo..
Thanks.

[meritosari]

Re: Asus K53SV - turn on with battery only

here you go

[bigsam731]

Re: Asus K53SV - turn on with battery only

I have the same board with the same problem. but these are reading I got on BQ24740:

1 3.3v
2 19v
3 19v
4 0v
5 2.6v
6 2.6
7 0v
8 0v
9 0v
10 3.2v
11 3.2v
12 0v
13 3.3v
14 0v
15 0v
16 0v
17 0v
18 1.5
19 1.5v
20 3v
21 0v
22 0v
23 0v
24 1.3v
25 2.2v
26 2.2v
27 2.8v
28 4.4v

I'm trying to find out why am I only getting 4.4v instead of 19v on pin 28

[bigsam731]

Re: Asus K53SV - turn on with battery only

looking around, I found this https://drive.google.com/open?id=0B4...VZOEZyQ2dKLUJv

It had a marking on it W2F and founf out that its PMBT2907.

[Joseph cauchi]

Re: Asus K53SV - turn on with battery only

Check this schematic

[DeniS182]

Re: Asus K53SV - turn on with battery only

meritosari thanks you very much! It works fine now, after soldered missing components.

[angel-boy]

Re: Asus K53SV - turn on with battery only

What did you change to fix the problem ? thanks