3437 odd initialisation / boot / sleep behaviour.

[G.Beard]

I've worked on this board before. Not sure if it was a liquid repair or not but I don't think it was.
Screen turned on then back off after a few seconds so I tied backlight PWM to S0, thought solved and sent it out thinking it was done.... Now thinking it could be something to do with what's presenting now.

So if I power this machine afer shutting down from OS it will chime, boot, everything works.
Close lid, sometimes powers off instead of deep sleep after some time.
When it powers off instead of sleeping - Turn it back on with no chime and no keyboard or trackpad.
After booting to OS login screen, SMC reset and power on again it will chime and everything working.

Any pointers please?

 

[PhilipC]

Have you tried a known good dc-in board

 

[G.Beard]

Have you tried a known good dc-in board

Yes same thing out of the case (on test IO board) with screen, BK, Tpad, etc attached... But I can't see how IO board would have anything to do with it...?

 

[TCRScircuit]

On stuff like this i'd say throw it in the UC and see if it is fixed....

But you said you tied BKL PWM to S0? Why? Was it missing? Maybe the PCH was screwed up and is even screwed up worse now? Maybe some corrision under it?

 

[G.Beard]

On stuff like this i'd say throw it in the UC and see if it is fixed....

But you said you tied BKL PWM to S0? Why?

eDP_BKLT_PWM would turn on for a few seconds and then off. Removed R7704 and connected 3V3_S0 to U7701 pin 4.
Sent it out with working screen.

MacBook returned back from custmer and now

Power this machine afer shutting down from OS it will chime, boot, everything works.
Close lid, sometimes powers off instead of deep sleep after some time.
When it powers off instead of sleeping - Turn it back on with no chime and no keyboard or trackpad.
After booting to OS login screen, SMC reset and power on again it will chime and everything working.

 

[larossmann]

For me that is often a bad trackpad/trackpad cable.

 

[G.Beard]

For me that is often a bad trackpad/trackpad cable.

It's not t-pad or cable or KB. I replaced both.
It follows a pattern...... I'll figure it out

 

[dukefawks]

Corrosion somewhere is likely. UC the fuck out of it and try again.