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820-00431-a no power IMac a1418
- Thread starter mogly
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First of all, welcome to the forum!
Schematic and boardview here:
drive.google.com
Trigger SMC_ONOFF_L and check for drop pulse at PM_PWRBTN_L (at same time).
Use J5120 pads, instead of power button.
Schematic and boardview here:
00431 J94.rar
drive.google.com
Trigger SMC_ONOFF_L and check for drop pulse at PM_PWRBTN_L (at same time).
Use J5120 pads, instead of power button.
Read this thread first:
boards.rossmanngroup.com
Find any test point, or component connected to PM_PWRBTN_L, to check the pulse.
HOW TO collection
I hope this "How to" collection will help our members. I will possibly modify this post in time, if updates available. Trigger SMC_ONOFF_L (PMU_ONOFF_L): It reffers to simulate power button function, when the keyboard is not connected. We need to do this when we work with the board...
boards.rossmanngroup.com
As in the thread explained, just temporar contact; similar as pressing power button...
You must check for drop pulse at PM_PWRBTN_L at same time when trigger SMC_ONOFF_L.
This points to SMC issue.
Do you get 12MHz at Y5165?
If no o-scope available, post DC voltage on its pins.
Do you get 12MHz at Y5165?
If no o-scope available, post DC voltage on its pins.
Check if PM_SLP_S4_L pulses at same time.
When press the power button, PM_SLP_S4_L should go high, from 0V to 3V; not viceversa.
Do you get high PM_SLP_S4_L when the power is applied, before pressing power button?
Do you get high PM_SLP_S4_L when the power is applied, before pressing power button?
That's good, means the power on sequence starts when the power is connected.
Do you get S3 voltages too, when PM_SLP_S4_L is high?
Also check PM_SLP_S3_L and S0 voltages.
Do you get S3 voltages too, when PM_SLP_S4_L is high?
Also check PM_SLP_S3_L and S0 voltages.
Page 68 shows you the S0 enables signals.
Just follow each of them and check the corresponding power rails.
First confirm PM_SLP_S3_L presence, of course.
Just follow each of them and check the corresponding power rails.
First confirm PM_SLP_S3_L presence, of course.
Then do what I said; locate the S0 voltages, as above indicated.