Re: DG424/DG524 NM-B301 Rev 1.0 no display and power issue
Indeed, it is. Do you have +1.8ALW rail present?
Indeed, it is. Do you have +1.8ALW rail present?
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Re: DG424/DG524 NM-B301 Rev 1.0 no display and power issue
PL401 - 3.3V
PL402 - 5V
EC_RSMRST# 0v
EC_ON - 3.3V
VR_CPU_PWROK - 3.3V
ALW_PWRGD- 6.5V
EC_VR_ON - 3.3V
SUSP# -0v
PCH_PWR_EN - 3.3V
SYS_PWROK - 0v
PM_SLP_S3# - 0v
Unit is taking 30miliamp of power stable
+1.8VALW- 1.8V
EC_RTCRST#_ON- 4.2v
SYSON - 0V
LDO1_VIN -0V
LDO2_VIN -3.3V
PMIC_VCC -5.1V
+5VLP - 5.1V
ALW_PWRGD -3.8V -pulsing 5vComment
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Re: DG424/DG524 NM-B301 Rev 1.0 no display and power issue
My earlier point of view may be incorrect.
The EC is creating (driving) the signal with netname EC_RSMRST#. That is, the EC is in control of this reset line and the EC is keeping this line low using one of its GPIO pins. This may be due to the EC not working / not being powered / not being clocked / corrupt firmware used by the EC.
Remove all power, what is the resistance to ground of EC_RSMRST# ?
On your logic board, do you have the resistor stuffed @ RC9350 ?
Do you have the power rails present on the EC?
What are the voltage to ground readings of the following signals?
EC_SMB_CK0
EC_SMB_DA0
PMIC_SMB_CLK0
PMIC_SMB_DAT0Attached FilesComment
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Re: DG424/DG524 NM-B301 Rev 1.0 no display and power issue
Can you confirm this voltage to ground? It does not look correct.ALW_PWRGD- 6.5V
See attached. This status line should be ~3v (max).
What is the voltage to ground of your +3VALW rail ?Attached FilesComment
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Re: DG424/DG524 NM-B301 Rev 1.0 no display and power issue
No, it is not normal to have pulsing. This is an 'always on rail' so it should be a stable +3V an is required to power other critical parts.
If it is pulsing, then that regulator must be investigated for the EN (enable) pin of that chip. Is the EN pin pulsing as well ?
Update:
EC_ON is the ENABLE for the +3VALW rail. You have posted this to be @ 3v3 which is a good voltage for EC_ON.
Is EC_ON stable @ 3v3 ? If yes, then the logic board is requesting for the +3VALW to be ON.
At this point of the quick review - PU401 may be defective if there is no excessive load on the +3VALW rail.Attached FilesLast edited by mon2; 03-18-2023, 06:28 PM.Comment
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Re: DG424/DG524 NM-B301 Rev 1.0 no display and power issue
Ok - just read your last post. Best to update and post a fresh list when you can.
Need to confirm the voltage on ALL_PWRGD - it cannot be so high as posted earlier.Comment
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Re: DG424/DG524 NM-B301 Rev 1.0 no display and power issue
No, this rail should not be so high since the pull-up voltage is to +3VALW.ALW_PWRGD - 3.3v - 3.9v is it normal ?
The +3VALW rail is created by PU401. Specifically, confirm that the FB leg of PU401 indeed has a 1k resistor as shown in the schematic.
Do not power up the board if the FB circuits are ever missing else the output may overshoot and kill every part that is voltage sensitive and operates from the +3VALW rail.
Remove the solder blob @ PJ402 to isolate all downstream (aka consumer) circuits from this power rail.
Power up again. Confirm that you have stable +3v3 @ PL401. If you do not, replace PU401.
If you observe fluctuations on the power good line then +3VALW is not stable.
At +3v9 output on +3VALW, this may have caused damage for voltage critical parts.Comment
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Hi everyone,
I'm working on a MacBook Air 2020 (A2337, board 820-02016) and running into a strange USB-C issue. I've gone through quite a bit of testing and part replacement, but I'm stuck — hoping someone here can shed some light.
🛠 Original Issue
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