DA0r76MB6D0 black screen .2a drawn

[Bisketti]

Hi Im working on a DA0r76MB6D0 board no schematics only boardview avaiable but using the attached schematics.
The unit was originally dead no adapter light no response from powerbutton.
Changed bios and very kept failing so changed chip and tried original bios ,same thing. Replaced sio same so tried different bios and board responds to powerbutton and only draws .2a and black screen, cpu gets warm.
Pl23 1.8v
pl21 0.8v
pl8 0.8v
Pl5 0.9v
pl9 2.2v
pl17 3.3v
pl18 5v
pl19 1.5v

kbc_rst 0v
mainon 3.3v
s5on 3.3v
dwbswon#3.3v
ec_rcin# 3.3v
kbc_p+3v 3.3v
vcore 3.3v
ecpwrok 3.3v
ecwrst 3.3v

Help appreciated

[piernov]

Re: DA0r76MB6D0 black screen .2a drawn

I guess it's not POSTing at all?
Check voltage on APU_RST#, APU_PWRGD, +0.95VS5. Any activity on BIOS CS# pin?

[Bisketti]

Re: DA0r76MB6D0 black screen .2a drawn

No not posting.Also it switches on by power button but wont switch off by it.
APU_RST# 1.7v at R242
APU_PWRGD 1.8v
+0.95VS5 ok .95v
See attached pic of bios cs# pin

[Bisketti]

Re: DA0r76MB6D0 black screen .2a drawn

SUSB# 3.3v
SUSС# 3.3v

Any ideas?

[piernov]

Re: DA0r76MB6D0 black screen .2a drawn

Everything looks fine to me so I don't know why the BIOS POST would fail. Make sure the RAM & CPU are good and compatible with the board, check if any IC (Ethernet/audio/card reader) gets hot or looks bad.
Make sure you are using a good BIOS, maybe try with another dump.

[Bisketti]

Re: DA0r76MB6D0 black screen .2a drawn

I have tried about 4 different dumps all exactly same result. Im trying to find out why KBC_RST# from APu is 0v. I would like the signal order diagram so I can check the order the signals come in.

[piernov]

Re: DA0r76MB6D0 black screen .2a drawn

Ah yep, overlooked that one.
KBC_RST# comes from PCIRST# apparently. And PCIRST# being low doesn't make sense because APU_RST# is high. The PCI reset signal should come before the CPU reset signal AFAIK. Check R510, but I guess you've an issue with the FCH.
You can take a look at an AMD chipset datasheet. I can't find this specific one but another chipset should already give you an idea.

[Jokerx84]

Re: DA0r76MB6D0 black screen .2a drawn

i have the same problem but HDMI has picture!
RTD2136R and CPU replaced!

Sorry for the bad English!

[Stuki]

Re: DA0r76MB6D0 black screen .2a drawn

Hi guys I have the same problem.
I replaced KBC and I used 4-5 different bios dumps but nothing.
Any ideas?