Asus EB1501 power on failed

[Stephane R]

Hi all,

Since 2 weeks, my eeebox 1501 won't start. First, i thought bios bug or something like this. I found this helpful site which explain how to fix reboot issue with a clear CMOS :
http://kloakens.blogspot.fr/2012/04/...own-issue.html
Unfortunately, for me, it doesn't work
To check power switch, i measure the voltage on the switch himself . I see 5v before to press button and the voltage falls to zero after release the button. I don't have schematic, but i think the voltage should be return to 5v after release the button. The button should works like a reset circuit.
May be shortcut on power, like a bad capacitor ? I don't know ? All capacitors looks like corrrect (all are flat). Is it helpful to change them ?

Do you ever seen something like this on Asus eeebox ?

Thanks in advance,
Regards
Stéphane

[selldoor]

Re: Asus EB1501 power on failed

Tried reseating the Ram? Perhaps post good clear pictures of the back and front of the board - maybe someone will spot something.

[khaahk]

Re: Asus EB1501 power on failed

Have you tried another power adapter, these seem to be the weakest link...

[spidey]

Re: Asus EB1501 power on failed

Check EC, flash bios.

[Stephane R]

Re: Asus EB1501 power on failed

Thanks for your answers !

Selldor, I have already reseated the RAM but nothing had changed. Yes, i will post pictures ! Good idea but I have to find my camera

khaahk , may be power adaptor, yes. It 's seems ok to the voltmeter but i will change it to loboratory power supply. This will allow me to limit and measure the current. how many of ampere this small machine could consume in normal time ?

Spidey, how i can check EC flash bios ? i saw SPI pin connector just behind the EC bios.
May be i can use it to read the bios. Not so easy i think !

So, tommorow i will find camera and laboratory power supply

Thank you very much and have a good day
Regards
Stephane

[selldoor]

Re: Asus EB1501 power on failed

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khaahk , may be power adaptor, yes. It 's seems ok to the voltmeter but i will change it to loboratory power supply. This will allow me to limit and measure the current. how many of ampere this small machine could consume in normal time ?

Should be a good clue on the power adapter label?

[Stephane R]

Re: Asus EB1501 power on failed

Hi all,

I plugged my EeeBox on my laboratory power supply. The current consumption is only 0.05 A (about 1W) ! Maximum current labeled on the power adapor is 3,42 A ( so 65W with 19v) and i limited the current on my power supply at 0.5A to be sure do not destroy components. But, as soon as I press the ON button, the power supply indicates 0A.
If I had a permanent short circuit with one of the components, I should have a bigger current. So I assume that the system goes into safety mode and disconnect the power circuits.
Or the bios is corrupted as indicated by spidey and I'll have to play with spi !
But it seems possible :
http://bios-repair.co.uk/SPI-ISP/spiflash.html

I posted pictures, If someone sees something suspicious do not hesitate to tell me!

Thanks
Regards,
Stéphane

[dj_ricoh]

Re: Asus EB1501 power on failed

Hmm
Soldered cpu.. Where could be the problem.
Reflow cpu and cipset

[dellxps15]

Re: Asus EB1501 power on failed

first check voltage to this 8 pin, then if both side of each one is shorted:

[Stephane R]

Re: Asus EB1501 power on failed

Hello dellxps15,

first check voltage to this 8 pin, then if both side of each one is shorted:

2 resistors are supplied. One of them delivers 5.29 V and the other 3.13V. The 5.29V voltage is the same I found on USB. These voltages are issued by Mosfet "k0355" controlled PWM I think (I would have checked with oscilloscope).
And then when I press ON I lose all voltages except the 19v applied to the mosfets. I do not think the mosfet are damaged because when I have no output voltage, the Gate is no longer supplied.

Regards,
Stéphane

[Stephane R]

Re: Asus EB1501 power on failed

Hmm
Soldered cpu.. Where could be the problem.
Reflow cpu and cipset

Hello dj_ricoh,

Maybe but I keep this method as last chance ! It's a bit complicated for me

Regards
Stéphane

[3d0]

Re: Asus EB1501 power on failed

I think what dellxps15 was trying to say is, check if the coils are short to ground.

[Stephane R]

Re: Asus EB1501 power on failed

I think what dellxps15 was trying to say is, check if the coils are short to ground.

Ho, sorry, I thought it was resistors! In ohmmeter, one of them (the lower) shows only 3.5 ohm connected to the ground. It's low! While all of them are behind a mosfet in series with the supply line! I will investigate that !

Thanks