Asus X555LD Rev. 3.1 no power

[Conste]

Re: Asus X555LD Rev. 3.1 no power

PU 9100 was soldered today. Problem persists, I think +3VA_EC is on short.

Shall I put 3v on this rail and watch which component gets warm?
Resistance to grund of 3VA_EC is only 1,5 ohms.

/edit: Or shall I desolder the KBC / SIO chip and see if +3VA_EC is present then?

[caspian]

Re: Asus X555LD Rev. 3.1 no power

Now, remove PSL9101 and check pins of PU9100 for being shorted.

[Conste]

Re: Asus X555LD Rev. 3.1 no power

PSL9101 was removed -> +3VA_EC is there after PU9100. If I bridge PSL9101 I get a reading of 200 mA (dropping), is this too much?

After removing PSL9101, power regulator module isn't getting warm anymore.

[caspian]

Re: Asus X555LD Rev. 3.1 no power

Do not bridge them. which pad of PSL9101 is shorted now?

[Conste]

Re: Asus X555LD Rev. 3.1 no power

Pad 1, the one next to the KBC / Super I/O Chip.

Pad 2, the one next to PU9100 is on 3,3V

So I guess, the KBC is bad?

[caspian]

Re: Asus X555LD Rev. 3.1 no power

Pad1 of PSL9101 is connected to KBC and lots of other components. you have to inject voltage on this pad to see which one gets warm. but keep PSL9101 removed. It is a bit risky, so keep the voltage low such as 1v or 2v.

[Conste]

Re: Asus X555LD Rev. 3.1 no power

tried it with 3,3v and 0,5A current limiter -> KBC gets warm

laboratory power supply shows short

[caspian]

Re: Asus X555LD Rev. 3.1 no power

If KBC is shorted, you should replace it. First, make sure no other component is shorted in that line. Have you got a programmer to program the KBC after replacement?

[Conste]

Re: Asus X555LD Rev. 3.1 no power

How can I make sure that no other component is short? Or could it be a part after the KNC?

No I don‘t have a programmer...or could I use the KBC of the other board?

[caspian]

Re: Asus X555LD Rev. 3.1 no power

just make sure no other component gets warm. since they are tiny, you may ignore them.
you can desolder KBC from another board, then you have to reprogram it. So you need a KBC programmer anyway. Of course, you can ask someone in your city to program it for you.

[mcplslg123]

Re: Asus X555LD Rev. 3.1 no power

You can buy a new kbc, it will get programmed automatically in asus(as long as it is blank). If you de solder from another mb, then it is not blank-so you will need a kbc programmer. If you dont have kbc programmer, it will be wiser to buy a new kbc .

Btw, Desolder the kbc and then power the mb and see if you are getting +3V_EC before ordering new kbc to be sure.

[Conste]

Re: Asus X555LD Rev. 3.1 no power

Thank u guys, I will try to desolder the KBC chip and test for short again.

[Conste]

Re: Asus X555LD Rev. 3.1 no power

KBC was desoldered, unfortunately I destroyed one pad - but I think this can be fixed with a wire. Pin is for FAN_PWM, so not soooo important.

Short is not present anymore, current = 0A when laboratory supply put on +3VA_EC.

I will report when new KBC is soldered in.

[mcplslg123]

Re: Asus X555LD Rev. 3.1 no power

Good luck

[Conste]

Re: Asus X555LD Rev. 3.1 no power

Hello,
Board does still not work. Will try to solder the kbc tomorrow again.
The board doesn‘t even charge the battery nor power on with new kbc. Maybe soldering was shit, idk.

[caspian]

Re: Asus X555LD Rev. 3.1 no power

check all the pins for connectivity to the pads. make sure no two neighbor pins are shorted together.

[Conste]

Re: Asus X555LD Rev. 3.1 no power

New KBC soldered in and check done. LED for power supply plugged is on, but just very low.

No power on possible.

+3VA_EC is available and okay - where to go on?

[caspian]

Re: Asus X555LD Rev. 3.1 no power

first check whether any pin of the KBC is shorted to GND. then, measure voltages on pins of the KBC to see which ones have voltage.

[Conste]

Re: Asus X555LD Rev. 3.1 no power

Is there no more advanced possibility to do this? I am pretty sure that all points are correctly soldered together.
Any test points to test?

[caspian]

Re: Asus X555LD Rev. 3.1 no power

there is no more advanced method than checking voltages on the pins. first check the VCC pins of KBC. there is no need to check KSI and KSO pins now. the other pins are important.