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820-00034 imac 21" 1#led
- Thread starter yair37
- Start date
"PP3V3_S4 pulsing 3.3v-0v when i trigger SMC_ONOFF_L."
Do you mean that 3V3_S4 is present BEFORE pressing power button?
Check S5_PWRGD and PM_DSW_PWRGD.
Do you mean that 3V3_S4 is present BEFORE pressing power button?
Check S5_PWRGD and PM_DSW_PWRGD.
If CMOS cell is removed, board will try to start when power supply is connected.
However, you should get more voltages, not only S4.
"can find S5_PWRGD on boardview" (you've probably meant can't).
What about PM_PGOOD_REG_P3V3_S5?
When you look at schematic, try to understand what you see there.
Also be aware, sometime name differences appear between schematic and boardview.
This shouldn't be a problem for a technician.
When 3V3_S4 is there, check PM_SLP_S4 level (before pressing power button).
However, you should get more voltages, not only S4.
"can find S5_PWRGD on boardview" (you've probably meant can't).
What about PM_PGOOD_REG_P3V3_S5?
When you look at schematic, try to understand what you see there.
Also be aware, sometime name differences appear between schematic and boardview.
This shouldn't be a problem for a technician.
When 3V3_S4 is there, check PM_SLP_S4 level (before pressing power button).
Last edited:
"3V3_S4 0V"
You've said to get 3V before.
Also I don't see any mention about PM_SLP_S4, as I asked.
S5_PWRGD shouldn't drop when you trigger SMC_ONOFF_L.
Change Q6970, if note it drops.
You've said to get 3V before.
Also I don't see any mention about PM_SLP_S4, as I asked.
S5_PWRGD shouldn't drop when you trigger SMC_ONOFF_L.
Change Q6970, if note it drops.
""can find S5_PWRGD on boardview" (you've probably meant can't).
What about PM_PGOOD_REG_P3V3_S5?"
Do you see any difference between these two signals???
"When you look at schematic, try to understand what you see there."
What about PM_PGOOD_REG_P3V3_S5?"
Do you see any difference between these two signals???
"When you look at schematic, try to understand what you see there."
Looks like SMC issue.
Once S5_PWRGD is high, SMC must release PM_DSW_PWRGD.
Did you solder SMC pulled from same model board?
Once S5_PWRGD is high, SMC must release PM_DSW_PWRGD.
Did you solder SMC pulled from same model board?
After two years on the forum still have doubts about SMC replacement?
Get the correct SMC for this board...
Get the correct SMC for this board...
some update,
i was get "new" board, install it and it was work great for 2 days...suddenly it was not turn on, i was open it and now just one led on, when i press power button the #2 led turn on for half second and off(like is short or something) pp3v3_s4 0v when i press power button it jump to 0.8v and back to 0v.
very weird!
i was get "new" board, install it and it was work great for 2 days...suddenly it was not turn on, i was open it and now just one led on, when i press power button the #2 led turn on for half second and off(like is short or something) pp3v3_s4 0v when i press power button it jump to 0.8v and back to 0v.
very weird!
Try changing Q8450.
Check for short on any S3, or S0 power rail.
Check for short on any S3, or S0 power rail.
If LE032 flashes, means ALL_SYS_PWRGD is pulsing.
So all voltages controlled by PM_SLP_S4L and PM_SLP_S3L should pulse too.
Check them all.
So all voltages controlled by PM_SLP_S4L and PM_SLP_S3L should pulse too.
Check them all.
Then you should get pulse on all S3 and S0 voltages (at same time).
Same behavior without RAM?
Same behavior without RAM?