asus K55VD - no power

[cephei328]

Hi guys,

I have Asus K55VD motherboard - Dc to Dc controller chip RT8239b is getting hot - when tested - 3.3 volts Always ON voltage is missing - but 5 volts always ON is present. Don't have schematics to trace the 3.3 volts always ON power rail . Help is much appreciated

Note: This 3.3 and 5 volts always ON will be present even before pressing power button and feeds EC and charger IC. When power button is pressed 3.3 and 5 volts system power will come out of RT8239b chip.

[cephei328]

Re: asus K55VD - no power

Ok guys, I got it. Its EC chip short causing d/c to d/c controller hot. Replaced EC all good.
cheers

[dj_ricoh]

Re: asus K55VD - no power

Ok guys, I got it. Its EC chip short causing d/c to d/c controller hot. Replaced EC all good.
cheers

i swear i try to understand .
usually EC chips are NUVOTON, ENE, ITE.
What EC chip did you have?
or you call Mosfets EC?

[atsio]

Re: asus K55VD - no power

EC ic gets 3.3v (power) from 5v and 3.3v regulator. EC ic was shorted, so 3.3v rail was sorted.

[cephei328]

Re: asus K55VD - no power

Atsio was right, EC ITE8517E gets 3.3 volts standby voltage from RT8239B system power controller. When EC is short no 3.3 volts and chip gets hot. Cheers

[gelf1969]

Re: asus K55VD - no power

Hi people,

I'm having trouble locating the RT8239B, is it under the CPU cooling pipes?
Any help would be appreciated.

Cheers

gelf1969

[gelf1969]

Re: asus K55VD - no power

I see my bad, must learn to have "coffee before tronics".

You were referring to a short with the EC ITE8517E causing a loss of continuous power to the RT8239b causing the issues.

Sheesh, might have my work cut out for me as a novice solderer sorting that ITE8517E replacement.

[ktmmotocross]

Re: asus K55VD - no power

just good flux and hotair station for removing, good flux and flat tip to soldering

[gelf1969]

Re: asus K55VD - no power

Would a Hot air gun work? Also would solder paste be a better solution for surface mounting?

Seriously don't mind if it goes belly-up since It has been thrown out.

[Ramee]

Re: asus K55VD - no power

Why don't you invest at least 1K usd to start. If you would like to become a goood technician, always do the proper way

[alter_sack]

Re: asus K55VD - no power

Hi everyone,

my board shows the same symptoms.
I do not know a lot about microelectronics, but I believe an EC would have to run some device-specific routines. Does this mean I have to get a programmed chip from another k55vd board, or does any IT8517E off ebay just work out of the box?

PS in case anyone is still looking: RT8239B is hidden under the heatpipe, a 3x3mm chip marked "jc ed h21".

[satanicko]

Re: asus K55VD - no power

hi i have a same board Asus K55vd board but no display I need your help guys tnx

[engsaif]

Re: asus K55VD - no power

hi friends pleas i need schematic diagram asus k55vd ...

[Legion007]

Re: asus K55VD - no power

Help me find a malfunction!
in the attached PDF note my measurements.
any help...
I place the necessary files for help

[Legion007]

Re: asus K55VD - no power

the LED energy is constantly on. LED lock 1 flashes twice. LED lock A glows constantly. After two seconds all the LEDs go out. the system does not start. the screen does not light up.. when the memory is removed. LED energy is shining. LED lock 1 is shining, constant glow. the processor is warming up, also warm bridges. After some time the fan turns on. the monitor does not light up. this may indicate a functional bios?

[Legion007]

Re: asus K55VD - no power

PM_RSMRST & PM_PWROK low levels 3,28V (should be 4V)

ALL_SYSTEM_PWRGD 3,33v but the laptop turns off, if dismantled memory laptop will not turn off, but the screen does not glow

any ideas ???

[piernov]

Re: asus K55VD - no power

Those voltages are 3.3V AFAIK. If RSMRST# is low, the system shouldn't react to power button at all.

[Legion007]

Re: asus K55VD - no power

problem with bios? I have no experience in diagnosis. any assumptions on the steps?

[Legion007]

Re: asus K55VD - no power

the failure of the BIOS program was confirmed, at the comparative analysis of a dump of a bios from the given mb and the bios of the downloaded from a network with obviously working mb the distinctions. after the firmware the notebook revived. updated the firmware without soldering the chip with a clothes clip.