Acer Aspire S7-392 Power Failure

[jacen17]

Hi all
I recently spilled a glass of liquid on my Acer Aspire S7 and since then the laptop has completely died (no LEDs, fans, power of any kind). I am an EE familiar with power electronics, but not really PC power architecture, so I am learning as I work through this.

I've completely disassembled the laptop and am powering just the motherboard with no other peripherals (SSD, fans, etc). I have verified that 19V is good and my 5V_S5 and 3.3V_S5 are good and I also have USB power. I have also validated that the power button sets KBC_PWRBTN# to 0V when pressed. I have not detected any short circuits anywhere (surprisingly), although parts of the board visually look somewhat "corroded".

The power state machine seems to be hanging at the KBC assertion of RSMRST# which is stuck at 0V regardless of the power button being pressed - this is preventing the remaining power from coming up including the CPU. From reading other posts on this forum this pointed me to a potential BIOS issue. I hooked up the BIOS SPI flash U2501 (schematic attached) chip select pin to my oscilloscope and it is stuck at a DC 2.7V, looks like data is not transferring so as I understand it, the BIOS is likely corrupted...right?

So my questions are
1. Am I going down the right path? Does it seem like there is an issue with U2501 either firmware or hardware?
2. How can I flash the Winbond SPI Flash device U2501? Can I do it on-board? What type of programmer should be used?
3. Acer has BIOS files on its website, but they are .exe's - how do I access the raw files (not sure what file extension) that the programmer requires?

The attached schematics have a power flow diagram on pages 99 and 100, although the state diagram on sheet 99 looks slightly inaccurate and may be for a different board.

Greatly appreciate any guidance here
Thank you
-Jason

[jacen17]

Re: Acer Aspire S7-392 Power Failure

OK, so I think I can find a programmer at work and should be able to flash the BIOS but I'm having trouble finding the .bin file - Acer only provides an extractable .exe with a .fd and some other files in it. Since I'm programming the chip directly rather than through a USB interface, where can I find the .bin?

thanks
-Jason

[toufik sat]

Re: Acer Aspire S7-392 Power Failure

Merci thank you

[jacen17]

Re: Acer Aspire S7-392 Power Failure

Alright, so I was able to reprogram the BIOS using a CH341A programmer I bought on Amazon. I found a .bin file online, but have no idea if it is good or not, all I can tell is that the file size matches up to the size of the PROM.

I did read and save the original .bin file that was on the EEPROM but I don't know how to tell if it was even corrupted in the first place.

Either way, no change to behavior with the new BIOS image on the EEPROM and reinstalled on the board. Chip is getting power, but no activity on clock or data lines (stuck at 0V) and CS is stuck at 2.7VDC.

I know the KBC is getting power because it is putting out 3.3V on the PB_RST signal. What else can I check for at this point?

[highpulse]

Re: Acer Aspire S7-392 Power Failure

tell us board code for we can provide a good and correct dump . but alltough if water was spilled on board , you got certainly dead components , specially resistors !!!! chek carefully the water damaged areas , and with c«schematic , chek if resistor have same value as mentioned on the schematic , somethings is wrong on voltage rails , so thats why it wont turn on ... you can try bios .. but sincerely after water spill no longer turning on , doesn't seem bios issues !

[highpulse]

Re: Acer Aspire S7-392 Power Failure

wich bios pin have you noticed does 2.7 volts ????

[jacen17]

Re: Acer Aspire S7-392 Power Failure

The motherboard is a Wistron Storm 2, part number 12302-1, revision 1, if somebody had a BIOS dump I'd be very grateful.
The pin stuck at 2.7V is Chip Select, pin 1.

I will do a more in depth look at KBC power and surrounding components. I have already had to replace one resistor due to corrosion.

[jacen17]

Re: Acer Aspire S7-392 Power Failure

I'm going to attempt replacing the KBC. Looking under the package with a microscope there looks like a lot of residue. It's a high density BGA package so I might need to send it out to be replaced. I can buy a replacement on ebay...

http://www.ebay.com/itm/Lot-of-iTE-I...-/252094880315

All the power to the chip is good that I can tell - I know this because the KBC is putting out 3.3V on the KBC_PWRBTN# pin so the chip has power.

Dumb question...does the keyboard need to be connected for the KBC to work? I have no peripherals connected to the MB.

[chrisart]

Re: Acer Aspire S7-392 Power Failure

GOOD DAY., having a 2.7v in CS pin on your spi chip most likely your chip is deselected, means no process data from spi chip..im having the same problem of yours and still i cant find any solution.,i have change working KBC (SIO) chip from another same and working motherboard but no changes..hope we're find an answer from the master..