820-4924AMissing S4 rails & PM_SLP_S5_L

[posarah]

Hi All,

Just wanted to see if I can get some assistance on a A1502 820-4924A I'm working on. Charger I'm using is a 85W magsafe 2 (straight from the wall not through a bench PSU) bought and used on two 3437s I was trying to fix so that should not be the issue.

Board looks spotless zero signs of liquid damage or corrosion, or even blown components (besides C7380 was cracked but not shorted rail was still present).

Below are the rails I've checked:
PP3V42_G3H = 3.43V
PPBUS_G3H 12.57
PPBUS_S5_HS_COMPUTING = 12.25V
PPVRTC_G3H = 3.3V
PP5V_S5 = 5V
SMC_BC_ACOK = 3.39V

Everything looked normal until I got to:
PPBUS_S5_HS_OTHER5V = 12.56v. Schematic says it should be 8.6v.
PPBUS_S5_HS_OTHER3V3 = Same as PPBUS_S5_HS_OTHER5V.

I then checked:
PM_SLP_S5_Lcompletely 0 no pulse
PM_SLP_S4_L ditto
S4_PWR_EN = 0V

Is PM_SLP_S5_L used in the A1502? I read a article while researching why it would be missing that most macbooks do not use this rail hence it's disappearance is usually a non issue. That said I did find another post on here where they were also missing S5_l/S4_L & were requested to note the below rails:

SMC_ADAPTER_EN = 3.4V
PM_BATLOW_L = 0V
S5_PWRGD = 3.35V
PCH_SRTCRST_L = 3.3V
PCH_INTVRMEN = 3.24V
PM_RSMRST_L = 3.3v
PM_SLP_SUS_L = 3.3V
PCH_DSWVRMEN = 2.96V
PM_DSW_PWRGD 3.43V

They were also asked if they trigger SMC_ONOFF_L if PM_PWRBTN_L changes.
PM_PWRBTN_L 3.42 on normal state 0V after shorting SMC_ONOFF_L. I also checked if PM_SLP_S4/S5_L pulse when first connecting the magsafe with SMC_ONOFF_L triggered and it did not both stayed at 0V.

Is there a way to check if the SMC is OK? I'm starting to suspect the SMC but unfortunately I do not have any replacements. and no A1502 donor boards. Are the 3437 or 00165 SMCs compatible?

Thanks for your assistance.

 

[2informaticos]

"Everything looked normal until I got to:
PPBUS_S5_HS_OTHER5V = 12.56v. Schematic says it should be 8.6v.
PPBUS_S5_HS_OTHER3V3 = Same as PPBUS_S5_HS_OTHER5V"
Did you check in schematic where these power rails come from?
Why would you expect 8.6V, if are connected directly to PPBUS_G3H (12.57V)?

Do you believe what you see and can confirm, or what someone else tells, even no confirmation on that?
Putin said he started an "military operation" into Ukraine.
We should think that is not war???

"PM_BATLOW_L = 0V"
PCH will not start power on sequence until get high level there.
Try starting with both charger and battery connected; trigger SMC_ON_OFF_L to start.

You forgot to check/post RTC_RESET_L and PCH_INTRUDER_L.

 

[posarah]

Didn’t trace it back just saw the annotation and took its word for it. I’m struggling to find a decent PDF viewer, the one I’m currently using has a nice bug where if you zoom in it shoots down 5 pages so I normally zoom into a level I’m comfortable with and can read things, than just use the search to bounce around where I need to be hence why I didn’t notice what line it was tied to.
This only came with the board, is the A1466 battery compatible? I only have that battery and the battery from the 1598. Both are probably stone flat though.

 

[2informaticos]

A1466 has 8.5V on PPBUS_G3H.
Do you think battery will be compatible?

What about the two missing RTC signals mentioned?

 

[posarah]

RTC_RESET_L = 3.41v PCH_INTRUDER_L. = 3.149V

 

[2informaticos]

Still need PM_BATLOW_L.
Is the charger ORIGINAL Apple Magsafe 2, 60/85W?
Try another one, just in case.

"PPBUS_G3H 12.57
PPBUS_S5_HS_COMPUTING = 12.25V"
Can you clarify this?
Is the same power rail...

 

[posarah]

Yup genuine magsafe 2 85W charger. I don't buy counterfeit chargers after seeing what it did to a customers Bose QC30s. Fake Chinese chargers melted the micro USB port and the plastic around the port. DC in board is a bit iffy though, waiting for my replacements to arrive so I have not tried another yet. I also do not have the cross flex/io board installed just magsafe.

PM-BATLOW_L is created by the PCH isn't it?

Think that's because I checked PPBus first before doing anything else, than replaced that split cap I mentioned which is on the S5 computing line. Changed the cap than checked the rest of the rails which is why I'm guessing computing was lower, as PPBUS is now also 12.25v. Cap I replaced it with may of been faulty though it did not read shorted when I checked it before and after installation.

Since missing PMSLP is usually dead PCH what resistances would you normally expect on a 2.7 8GB?
l7310 & L7320 I'm getting 9 ohm to ground on both.

 

[posarah]

Looks like something on PPBUS_G3H is shorted. I removed R5400 to isolate S5 isense from PPBUS and found diode mode of 0.06 where S5 isense is 0.4. Is it safe to run the board with that current sense resistor removed to do some voltage injection or should I reinstall it?

 

[2informaticos]

I don't understand you.
Have 12.25V at PPBUS_G3H and short to ground at same time?
Please, post useful information.