C850D beep no ram but no boot no image

[Learn2Day]

Hey,

I just got a C850D that turns on but no image and doesn't boot. But it gives me beep error with no RAM in it.

Could this be BIOS? I have a spare board of exact same model I can replace BIOS with, but before that, is there any BIOS recovery procedure available for this?

Thanks.

[atsio]

Re: C850D beep no ram but no boot no image

First try another CPU.

[Learn2Day]

Re: C850D beep no ram but no boot no image

Another CPU didn't worked. Also might be worth mentioning I hear a short crackling sound coming from the speakers when I turn on laptop.

[Learn2Day]

Re: C850D beep no ram but no boot no image

CPU, GPU and NB are heating up significantly. But after a few seconds fan kicks in and the seem to hold their temperature in check.. In a minute or so laptop turns off but it's hard to say if this is related to temp or not, considering you have no visible boot.

What do you guys think, should I start with BIOS or just do a quick reflow to see if it boots? I usually like to avoid reflow until all options are exhausted, I'm always afraid to damage the board.

Thanks.

[atsio]

Re: C850D beep no ram but no boot no image

measure voltages on all pins of lvds.

[Learn2Day]

Re: C850D beep no ram but no boot no image

pins 3, 35, 37, 39 - 3.3V
pins 2, 4 - 19V
all other pins read virtually 0V.
Didn't mention before but I did test laptop both with display and external.

Thanks.

[atsio]

Re: C850D beep no ram but no boot no image

What is the model of the motherboard?

[Learn2Day]

Re: C850D beep no ram but no boot no image

Not quite sure.
Seems to be PLAC/CSAC DSC REV:2.1
thanks

[Learn2Day]

Re: C850D beep no ram but no boot no image

Can someone help me find the schematics and locating BIOS chip on this model?

Thanks.

[atsio]

Re: C850D beep no ram but no boot no image

Your are looking for Pegatron PLAC/CSAC DSC REV:2.1 which is quite difficult to find.

[Learn2Day]

Re: C850D beep no ram but no boot no image

Do you think it might be corrupt BIOS? I don't think it's GPU related, with GPU probably wouldn't even post beep errors.

[atsio]

Re: C850D beep no ram but no boot no image

You will never know until you try it

[Learn2Day]

Re: C850D beep no ram but no boot no image

Can you help locate BIOS chip? I'm all that much noob..

http://www.filefactory.com/file/5sjs...AC_DSC_2.1.rar

Thanks.

[lezsimply]

Re: C850D beep no ram but no boot no image

On pic 002, left side near memory card reader beside ati chip. Its labeled winbond which I think is a 200mil soic.

[Learn2Day]

Re: C850D beep no ram but no boot no image

Thank you lezsimply!!

[Learn2Day]

Re: C850D beep no ram but no boot no image

Hey, I really need your help..

I replaced BIOS chip with the spare one I had and tadaaa!! It worked!

After this I re-assembled the laptop, powered it on, entered BIOS, changed the time and saved it. Got no media error due to formatted hdd, rebooted to boot Win instalation and it froze! Now it won't turn on or even light the charge battery led!

What did I do wrong?

I already tried to remove CMOS battery, battery, charger, it simply doesn't power on.

Please HEEELLPP!!

Thanks.

[highpulse]

Re: C850D beep no ram but no boot no image

if im not mistaquen your SIO chip is a nuvoton 781 , if after replacement machine worked , and after a while died again ,could be the SIO chip damaged , making your bios to get corrupted , try replace Sio chip , and reflash bios again , and let us know

[Learn2Day]

Re: C850D beep no ram but no boot no image

Thanks,

But 1st, I don't have a BIOS programmer, and second i need help locating SIO chip.

[lezsimply]

Re: C850D beep no ram but no boot no image

On pic 001, left side the big square one with many pins. close to hole H6502 and H6525. With marking NUOVOTON

[Learn2Day]

Re: C850D beep no ram but no boot no image

Thanks.

Confirmed it's not SIO chip. Soldered last BIOS again and laptop turns on again, RAM error, etc..

I need to flash BIOS but I don't have a BIOS programmer on me. Only thing it comes to mind is try a crisis recovery.

Can anyone help me here?

Thanks.