How does a KBC normally get its power?

[orientalsniper]

I'm having trouble with an Asus laptop, no schematics, BIOS is not receiving power, so I'm wondering how does the KBC get its power since I swapped with a new one and problem remains.

[atsio]

Re: How does a KBC normally get its power?

You have to look at the datasheet of the IC.

[orientalsniper]

Re: How does a KBC normally get its power?

Can't find it, it's an IT8572E.

[Bisketti]

Re: How does a KBC normally get its power?

kbc get its initial power from the 3.3v/5v regulator if you are not getting the 3.3v Always on voltage the KBC and the powerbutton wont get its power, so the laptop wont start.

[atsio]

Re: How does a KBC normally get its power?

Have a look from a schematic
That is ITE 8572E in the schematic

[orientalsniper]

Re: How does a KBC normally get its power?

kbc get its initial power from the 3.3v/5v regulator if you are not getting the 3.3v Always on voltage the KBC and the powerbutton wont get its power, so the laptop wont start.

Thank you, so: power regulator > KBC > BIOS?

Have a look from a schematic
That is ITE 8572E in the schematic

Thank you, what motherboard is the schematic for?

[Bisketti]

Re: How does a KBC normally get its power?

Thank you, so: power regulator > KBC > BIOS?



Thank you, what motherboard is the schematic for?

Flow is usually something like.. dc jack>charging circuit>3.3v/5v regulator> from here onto Sio,Bios,powerbutton. This is usually called your 3.3v ALWS voltage or always on voltage. The powerbutton is connected to a pin on the KBC (PWRBTN#) and when it is pressed the voltage goes to 0v as does the pin on the SIO(KBC) this in turn causes the KBC to start. The most important pins at the start are #RSMRST and S5_Enable. Having the correct schematic will help a lot even if you have to buy it.

[atsio]

Re: How does a KBC normally get its power?

You've watched a lot of the indian's guy videos. S5 is on before you press power button. When you press power button, SIO releases SUSON.

[orientalsniper]

Re: How does a KBC normally get its power?

What is SUSON?

[atsio]

Re: How does a KBC normally get its power?

Suspended power on. Look at the ACPI interface, http://en.wikipedia.org/wiki/Advance...ower_Interface

[orientalsniper]

Re: How does a KBC normally get its power?

So you actually meant VSUS_ON, also the schematic you gave me is wrong, I'm working in a IT8572E, the one you gave me is IT8752E.

[orientalsniper]

Re: How does a KBC normally get its power?

Found it!

[atsio]

Re: How does a KBC normally get its power?

Sorry, have a look at this https://cdn.badcaps-static.com/pdfs/...ae29ea474a.pdf

[atsio]

Re: How does a KBC normally get its power?

We found the same

[orientalsniper]

Re: How does a KBC normally get its power?

Hello again, I'm not sure if I soldered all the pins in the KBC to the motherboard since I don't have magnifying lens. What pins can I test in the KBC?

[atsio]

Re: How does a KBC normally get its power?

None, you must check each pin on IC against neighboring pins for short.

[Bisketti]

Re: How does a KBC normally get its power?

You've watched a lot of the indian's guy videos. S5 is on before you press power button. When you press power button, SIO releases SUSON.

What difference does that make?. The flow is the same. Dont try confuse the other person. The flow I posted earlier is enough to ascertain if the issue is with the Sio/Vin or bios. Not sure why you even commented this. If you have power to the sio/bios/powerbutton then your 3.3v/5v regulator is ok at this point. if you press the powerbutton and the sio does not output 3v from the RSMrst# pin the more than likely is a bad bios chip or bad flash or bad KBC. You should not change out the KBC chip until you have identified it as the issue.
I have already this week repaired a 1525 with bad bios using this method and also a toshiba c660 which had a faulty KBC also using this method. If your method works for you then thats good. Im just trying to assist.

[atsio]

Re: How does a KBC normally get its power?

You cannot do smt work without a proper magnifing glass.

[atsio]

Re: How does a KBC normally get its power?

What difference does that make?. The flow is the same. Dont try confuse the other person. The flow I posted earlier is enough to ascertain if the issue is with the Sio/Vin or bios. Not sure why you even commented this. If you have power to the sio/bios/powerbutton then your 3.3v/5v regulator is ok at this point. if you press the powerbutton and the sio does not output 3v from the RSMrst# pin the more than likely is a bad bios chip or bad flash or bad KBC. You should not change out the KBC chip until you have identified it as the issue.
I have already this week repaired a 1525 with bad bios using this method and also a toshiba c660 which had a faulty KBC also using this method. If your method works for you then thats good. Im just trying to assist.

I do not dissagree with the general idea but it all depends on the design. You were talking for two signals from SIO and now you mention one. In the image I had attached previously of KBC controller, that signal was SUSON which is generally the signal used.
When I say depends on design, a lot of the times KBC starts after signal from SOUTH and in many new designs SPI is controlled by "southbridge-northbridge".

[atsio]

Re: How does a KBC normally get its power?

Furthermore (as I say it depends on design), If you have power on SIO it doesn't mean that 3.3 and 5v regulator is O.K., i.e. a lot of designs they use the REG3 (LDO) pin to power SIO and then they get an EN signal to raise 3.3 and 5v.