G74A motherboard shuts down

[bjhawfam]

Working on a DAG74AMB8D0 motherboard.. The power light turns on and the fan spins (sometimes) for about 2 seconds and shuts down.. I originally thought bios perhaps (checked several core voltages) and reprogrammed the sop8, no change.. I've included the schematic in hopes of some ideas.. Could the video portion of the CPU be bad, no vcc? Any ideas would be helpful..

[MOD EDIT] Link to schematic -> https://www.badcaps.net/forum/troubl...b8d0-schematic

[Agent24]

Re: G74A motherboard shuts down

Have you checked all the voltage rails and system control signals? (Especially such like power_good signal etc)

Bear in mind the EC/KBC can also have its own BIOS which may be corrupted, separate of the system BIOS.

[bjhawfam]

Re: G74A motherboard shuts down

I checked for the following voltages

19.5 present
5vpcu present
3vpcu present

The following voltages a present when the power button is pushed

5v
3v
1.5v
1.0v
1.8v
3.2v

all present after power is applied only briefly than the boards shuts off..

[bjhawfam]

Re: G74A motherboard shuts down

If the KBC/EC was corrupted wouldn't it be possible to test..?????

When the power button is pushed it is detected at the KBC pin 2,,,, 3v to 0 than back... checked respective voltages out from kbc and all seems okay including fansig,,, Pin 119 RSMRST# gets 3.2v after power button is pushed.... Bios pin 8 gets 3v as well....

[bjhawfam]

Re: G74A motherboard shuts down

Wanted to add,,, The bios has been reprogrammed to exclude a corruption from bios...

[bjhawfam]

Re: G74A motherboard shuts down

If the board view is useful to anyone let me know!!!

[bjhawfam]

Re: G74A motherboard shuts down

Also not sure why, however, the fan sometimes starts for a second and others no movemment at all just the power LEDS come on.. I checked voltage at the fan and have proper voltage except for pin 4 FAN1_PWM gets 1.2v when it decides to turn on..

[Francisco.s]

Re: G74A motherboard shuts down

Wanted to add,,, The bios has been reprogrammed to exclude a corruption from bios...

IT8987 has its own internal bios.

Corruption in this internal bios could be the culprit.

I know for other motherboards that if you could erase IT8987 internal flash, it reprograms this flash from main bios, but I wonder if IT8987 has an easy way to erase its flash. ( probably only especial programmers can do)

Check also pcb for liquid or moisture damages.

[bjhawfam]

Re: G74A motherboard shuts down

Hello and thanks for the input. I checked and double checked for any signs of moisture and don't believe it to be the issue. If the internal bios (ec) can be erased within this chip and rewritten via the main bios, would it be possible to just replace the chip? Wouldn't there be evidence if the internal bios was corrupted, such as incorrect signals from the chip (such as the fan signal)?

Thanks again..

[Francisco.s]

Re: G74A motherboard shuts down

Wouldn't there be evidence if the internal bios was corrupted, such as incorrect signals from the chip (such as the fan signal)?

Data corruption makes unpredictable behaviors, so it's almost imposible to to say if fan anomalous control is due to bios or other fail in motherboard.

If you can change IT8987, most probably it will auto-program itself with special data for kbc contained in main bios.

I would give it a try. (seems a bios problem)

[bjhawfam]

Re: G74A motherboard shuts down

Thanks again,

I'll get one ordered and report back when and if it works..

[mcplslg123]

Re: G74A motherboard shuts down

Data corruption makes unpredictable behaviors, so it's almost imposible to to say if fan anomalous control is due to bios or other fail in motherboard.

If you can change IT8987, most probably it will auto-program itself with special data for kbc contained in main bios.

I would give it a try. (seems a bios problem)

I dont agree. It will not auto reprogram going by my experience in Quanta Y11A motherboard(same ite series). I reprogramed it with svod.

[piernov]

Re: G74A motherboard shuts down

It did reprogram itself on my Quanta Y11A so I'm not sure why it wouldn't work for you.
However the chip has to be blank I think, it will not work if it has corrupted data.
You need to power on the motherboard once on AC adapter after having replaced the EC, and made sure the BIOS is OK, and let it do its work, it will shutdown (or reboot, can't remember) by itself once it's done.

[bjhawfam]

Just in case, I'll order a svod programmer as well. Several ite chips are on the way already. I'll wait for the programmer and try it first (erase) to see if it auto programs.. Either way I'll have both bases covered. It will take a up to 2 weeks to report good or bad news..

[mcplslg123]

Re: G74A motherboard shuts down

It did reprogram itself on my Quanta Y11A so I'm not sure why it wouldn't work for you.
However the chip has to be blank I think, it will not work if it has corrupted data.
You need to power on the motherboard once on AC adapter after having replaced the EC, and made sure the BIOS is OK, and let it do its work, it will shutdown (or reboot, can't remember) by itself once it's done.

Ok piernov, might be my chip was not blank though it was new as per seller.

[bjhawfam]

Re: G74A motherboard shuts down

No such luck so far... I was able to wipe the 128kb within the ite chip via the svod programmer.. Now the leds dont come on at all and the fan doesnt spin.. When I try to power it on ,,,, nothing happens (no self programming).. I'm not sure at this point if it's worth trying to solder on a new chip. I couldn't find a viable .bin file to use to reprogram.

[Agent24]

Re: G74A motherboard shuts down

Try a main BIOS settings reset?

[bjhawfam]

Re: G74A motherboard shuts down

I tried several bios files and just went back to the original bios (sop8) via a programmer.. Now when I try to reflash the ec/bios (ite8987) using the SVOD I get an error message "the data does not match" ... So the ite chip is stuck wiped clean..

[bjhawfam]

Re: G74A motherboard shuts down

I do have an update on this matter...

The new ITE8987E chips arrived and I replaced it today... With a new bios in place and after the ITE was soldered on I powered the laptop on and found it in the exact state as the original post.. With a new eight pin bios chip and a different g74a bios downloaded onto it,, and with a new ITE8987E chip (blank) the laptop still powers on for a second and than back off... Interestingly, I can tell you that in fact the ite8987e is programmed automatically.. With the new chip in place I created a blank 128mb file and I wrote it to the ITE via the svod programer, however, the blank file was over written automatically when powered back on... So now, either I have two bad bios (8 pin ) files or the problem lies elsewhere.

[Agent24]

Re: G74A motherboard shuts down

Did you dump the original BIOS? If you did (you really should have) then put it back and try again.

Sounds to me like maybe you have a hardware problem. Go back to the voltage rails and power-up signals to start with.