Asus g501j, power jack nets - please explanation

[myth77]

I got this laptop from friend...he teared up power jack completely (but its common problem with this laptops), so..i am going to help him to replace it (if he didnt shorted motherboard completely), so i ordered a new power jack...and while i am waithing...i did a bit of investigation and i can see like four pins coming from power jack...so i was trying to download boardview but there is no boardview for this model..but there is for similar model asus n501, most important thing they have same power jack. So i attached picture of nets on power jack and that in the middle (red/yellow) are the pin lines inside the power jack.



So i have 2 ground, and one +V DCJACK going through the middle of power jack with 2 lines, and one A/D MAX POWER goint also through the middle of power jack with 2 lines...
And finally the question..what is this A/D MAX POWER? that pin and net goes directly to U3001 IT8585VG.. (last picture attached)...because the power jack is damaged..i can not see if the pin from charger 19v goes directly to this net...if that is truth then 19v is going directly to IT8585VG? If this 2 pins are not touching pin from charger then what is their purpose? What am i reading wrong?

thank you

[jasko_jacker]

Re: Asus g501j, power jack nets - please explanation

This is the datasheet of the DC power port, if the pdf is correct, I see a central pin that usually detect the power adapter in use.

[myth77]

Re: Asus g501j, power jack nets - please explanation

thank you...but if that is correct then this pin should not have contact to 19v charger pin ? but if so, how does it detect that charger is plugged? and if power jack is broken and charger pin touches this A/D max power net it will burn/destroy the IT8585VG? and maybe behind...?

[jasko_jacker]

Re: Asus g501j, power jack nets - please explanation

In this type of connector there are 3 contacts, one for GND one for DC (19V in this case) and another to check if the adapter in use is originally and what power (Dell use a one wire micro, etc)
in some cases the motherboard also starts without this connected pin, however this pin should never be connected directly to the 19 volt if you do not know what kind of signal it uses. What name does the pin have on ITE? What voltage does the central pin have on the power supply?

[myth77]

Re: Asus g501j, power jack nets - please explanation

On ITE the pin is A/D max power, charger voltage i will check later...

[myth77]

Re: Asus g501j, power jack nets - please explanation

Ok, so on ITE the pin is A/D max power, central pin and charger pin should have 19 v

[myth77]

Re: Asus g501j, power jack nets - please explanation

so update...as you can see in this picture this O ohm resistor PR8823 should be part of the A/D max power net..but when i measure continuity between power jack pin (A/D max) and this resistor there is no beep, no continuity, resistance is arround 1k ohm!..how is this possible? both pins on this resistor have continuity to the ground.

[BlueMidnight]

Re: Asus g501j, power jack nets - please explanation

Both of your boardview images are flipped vertically. Make sure you are doing your measurements on the correct pins.

The plug on the AC adapter has 3 contacts: Ground on the outside of the barrel, positive on the inside of the barrel, and a signal pin in the center.

I do not know for certain how this one works. I don't have any to test. But typically, there are 2 ways a signal pin is used:

1. As a serial data line, allowing the board to read the type/wattage of the AC adapter. (e.g. Dell style)
2. As the center point of a resistor divider. The first resistor is on the board (usually connected from a positive voltage rail to the signal pin) and the second resistor is inside the plug (normally connected from the signal pin to ground). The value of the resistor in the plug will determine the voltage on the signal pin, and this is used to identify the type of AC adapter. (e.g. Lenovo style)

Looking at several boardviews, I see that ASUS boards come in a few varieties:

1. No "A/D MAX POWER" signal at all
2. Has "A/D MAX POWER" signal connected to the EC and it is shorted to ground. The signal does not go to the DC jack at all.
3. Has "A/D MAX POWER" signal connected to the EC and it is shorted to ground. The signal is connected to the center pin of the DC jack. (e.g. the board you are working on)
4. Has "A/D MAX POWER" signal connected to the EC and it is connected to 3V via a 100k resistor. The signal is connected to the center pin of the DC jack.

The boardviews show both resistor positions (e.g. PR8822, PR8823), but only one has a component value (i.e. is actually populated on the board).

It doesn't seem like the signal pin is a serial data line. A 100k ohm pull-up resistor is a little high (~10k is more typical). But if it were a data line, it would seem that some boards don't care about it and just have a 0 ohm resistor to ground.

The signal line may be of the resistor divider type. But, again, some boards must not care about it and just short it to ground.

There's also a chance that the signal pin is meant to communicate something to the AC adapter rather than the other way around. But I can't imagine why.

It would be very useful to measure the resistance from the signal pin to positive and ground on the AC adapter plug (with it disconnected from the power outlet and the board). This would let you know if it is of the resistor divider type or not.

[subroto]

Re: Asus g501j, power jack nets - please explanation

The yellow lines in first pic is just for detecting a Asus Charger. Actually its measure the targeted pin impedance to detect the Watt rating of Adapter.