820-3536 no chime no display

[Glenn]

Liquid damage around C7373 fixed problem

cpu Vore present 1,8V
Light in usb mouse
No pictures on external screen
U1950 pin 8 3,4V

any idea?

 

[dukefawks]

Does it chime? Known good LCD?

 

[Glenn]

Don’t chime. Known good lcd yes. Also testing with external screen.
Also caps look dose’t light up.

 

[dukefawks]

History? Liquid? BIOS messed with?

 

[Glenn]

Liquid damage yes. And look like somebody have raped MagSafe hole.

mini display port is full off shit.

Bios chip loking ok. I don’t have bios reader.

 

[dukefawks]

Corrosion, the usual suspects, U1900 and traces to Y1905. U1950 pin 8. U6100 and all 16 termination resistors and traces, J6100.

 

[Glenn]

No Title

Pp3v3_s4 and Pp3v3_s3 is low.. only 2,84v

on pictures u8000

 

[smiba]

Thats an ugly looking U8000, replace it. Not sure if low PP3V3 can cause the no post issues, but it might screw up some chips or logic.

 

[Glenn]

I hope.. just order new one.

 

[Glenn]

now pp3v3_s4 and pp3v3_s3 is 3,3V
still no chime and no screen.
Could it be bad EFI?

 

[smiba]

Most likely not, in my experience it will usually show this symptoms when the SPI ROM is bad:

- Not enter S4
- Enters S0 and then goes back to S5
In some rare cases (bad ME) it might stay in S0 though, but this is probably one of the last things we should look into. I never had it happen for me

Did you inspect the clock IC (U1900), termination resistors and traces to the crystal like duke suggested?

 

[Glenn]

Y1950 i get 0.940V on pin 1 and 4
J6100 i already have removed
Will measuring u1900.

 

[Glenn]

on u1900 pin 8 what voltage should i have there ?

 

[smiba]

Not important, its the clock for the camera. (Which is not enabled so probably about 0V)

You can't really see if the clock is working properly by checking it with a multimeter, best to use is a oscilloscope or if you have a fancy multimeter it might be able to show the clock frequency (But most multimeters won't go above the Khz's)

Since the USB mouse lights up I'm having some doubts that it could be U1900, but it was worth checking. Any idea of there was liquid around that area?
Have you checked the SPI termination resistors?

Maybe Duke has a better idea though, lets see what he has to say

 

[Glenn]

Maybe ther could been some liquid around.
Also found a broken C8351.
But that has noting to do with no posting..

 

[dukefawks]

It could be anything. Dead U1900, crap under the SMC, U6100 termination resistors/traces, U1950 and what not. USB mouse lighting up?

 

[Glenn]

So I can try reflow smc? (Have tried smc bypass with no luck)
U1900 give voltage on all pins U1950 looking fine (don't know how to measure that)

Yes light in USB mouse. CPU getting little hot.

 

[dukefawks]

Uhh if a USB mouse lights the machine is kind of working. Connect a keyboard and do a PRAM reset and see if chime returns.

 

[Glenn]

Have tried pram reset with a know good keyboard. Still no chime or pictures.

 

[dukefawks]

Do it with an external keyboard. Also check if that mouse does not light on a dead board or a board without RAM inserted.