820-2249-A high speed fan. Black Screen. No Chime

[protocold]

No sign of water damage, board is clean.

Fan blast high speed as soon as magsafe is plugged in, led is green. Screen is black. No Chime.

When ram is in, no beep, When ram is out, slow ram beep. Put the ram back, no beep.

I measured all the power rail and all the voltages are correct, except

PPVCORE_S0_CPU is 0.98V instead of marked 1.25V. Is this ok actually?

where should I start?

 

[2informaticos]

Do you get AVREF_SMC?

VCORE depends on CPU VID lines configuration; specific to any CPU type.

 

[protocold]

PP3V3_S5_AVREF_SMC = 3.3v

Is that what you mean?

 

[piernov]

820-2249 will have dead GPU.

 

[2informaticos]

Heat GPU for test.
It will be difficult to find good chip for this board anyway.

 

[piernov]

see-ic still has some good ones (must buy them new with white underfill) but they are getting more and more expensive.

 

[protocold]

I was told this was a "new replacement board" from somewhere and the board is shiny and ultra clean [not entirely sure if it has been cleaned or what not]. There wasnt any sign of prior repair attempt.

Having said that the GPU could still be the culprit as both of you mentioned.

I am just trying to see what I can do on this. I actually tried to experiment on a 820-2101A (the 2007 model) where I removed the GPU and the board will still boot and chime with USB activities etc.

Is there a way I can isolate the GPU or disable the GPU in some way [without removing it] and see if the board is still ok otherwise?

 

[2informaticos]

Did the heat test on GPU?
180-200 C degrees for 15-20s; if reacts, then bad GPU for sure.
If no reaction, then you cannot discard GPU yet; but more chances is not the culprit.

 

[protocold]

I did. There is no reaction.

 

[2informaticos]

Can still be GPU issue.
Did PRAM reset?
Also disconnect CMOS cell.

 

[protocold]

I can turn it on and off with the power button..it even has orange light if i put in the battery.

But it doesnt respond to PRAM reset key sequence.

 

[2informaticos]

All temp sensors connected?
If any not connected, that be the reason for full fans spin.

 

[protocold]

you are right, i didnt have the heatsink on so one of the temp sensors wasnt connected.

I connected the heatsink back and not more high fan spin.

But still no chime and black screen.

 

[2informaticos]

Even no reaction at heat test, GPU still remains the first suspect.
Just in case, try known good BIOS.

 

[protocold]

I dont have a known good bios but I downloaded one from the internet... still the same....

Do you have a known good?

 

[2informaticos]

No, I don't have for this model.
I hope you didn't try one from vinafix.

Not much hope to be BIOS, but you need known good dump; to discard BIOS issue.
I saw you had other thread with similar board; read its BIOS and try.

 

[protocold]

The other board has more vram than this one. Would it works?

 

[2informaticos]

Yes, it should.

 

[protocold]

ALL_SYS_PWRGD = 3.23v
CPU_PWRGD = 1.04v
FSB_CPURST_L = 1.04v