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820-3462 Sleep awake cycle failure

S

Sellicks

New member
Hi everyone,
I am new to forum and looking forward learn. Thank you in advance .

820-3462 when it goes sleep wont wake up

I really dont have much idea how sleep awake cycle works .

I have checked the S3 and S4 rails all of them has power while mac sleeping .

I have start to measure around enables due to Mobile System Power State Table (Power Control 1/ENABLE)
But couldn't find the source of the problem .

I am looking for some wisdom to figure out the issue and understand how sleep awake cycle works .
Thank you.
 
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S

Sellicks

New member
Yes I have , Each time it fails to wake when its testing bluetooth or airport sleep cycle ! Anything related sleep awake cycle .
 
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S

Sellicks

New member
When it goes sleep it doesnt wake up only way to get it start is Power button .
I have test with most basic connection I have tested without airport camera or IO one by one even disconnected the screen test it with external Monitor .

It would be great to know Where should it first powers when you touch to keyboard or trackpad to wake it up ?
 
D

dukefawks

Administrator
It's a complicated system involving software and hardware. It is not just "turning on" the power again.
In sleep mode SLP_S4 and S5 should stay on, check that.
In most cases this is liquid damage somewhere, or the LAN chip but 3462 does not have that.
 
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aprendiz

Moderator
I have a 820-3476 with exactly the same issue, never manage to find the problem, still have the logic board somewhere, maybe I take a look tomorrow.... It is still a good ($$$) LB....
 
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dukefawks

Administrator
This will be too hard to diagnose. You don't know if the OS that was stored in RAM was corrupted or that something in the power cycle went wrong. The only thing to check is if the system enters sleep that all S3 power stays on. After that it is just stabbing in the dark, very complex problem. Although it may be only 1 resistor or FET, this will be a nightmare to diagnose. I still say liquid damage somewhere, possible cleaned already.
 
S

Sellicks

New member
I have double checked under the microscope there is no sign of L. damage
I will measure around little bit more before I give up on this and will post the results if there is any.
Thank you.
 
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