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820-3787 Boot Logo, Quits, Repeats Every 5 Seconds

M

mccafe

Member
Hello Guys,

I have here a 820-3787 board that is not properly working. It almost works with both battery and DC in connected. Apple logo would show for 5 seconds with loading bar, computer restarts, repeats. Green light on charger and fan spin.

When everything is disconnected and only the DC in adaptor is plugged in, it is stuck on an S5 state:
PPBUS_G3H is present
PP3V42_G3H is present + green light on charger
PP5V_S5 is present
P3V3S4_EN 0v
PP3V3_S5_PWRCTL is present
PM_SLP_S5_L 0v
SMC_S4_WAKESRC_EN 0v
SMC_ADAPTER_EN 3.3v
PM_BATLOW_L 3.3v
PM_PWRBTN_L 3.3v
PM_RSMRST_L 3.0v
PM_PCH_APWROK 0v
PM_PCH_PWROK 0v
PM_PCH_SYS_PWROK 3.3v (normally 0v, but I jumped from PP3V42_G3H_PCHPWRGD)
PCH_SUSWARN_L 3.3v
PM_SYSRST_L 0v

How should I proceed with this?

Thank you!
 
M

mccafe

Member
Green light then turns orange all while battery is disconnected. And yes original charger working on other laptops.
 
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M

mccafe

Member
I'd also like to add that it does try to load (Apple logo screen with loading bar up to 75%) when both battery and charger and then it restarts.
 
M

mccafe

Member
Tried testing a good USB drive with Install MacOS, but the screen that I get after holding option key shows for a split second and then restarts as well. It was long enough for me to make out that the SSD is being recognized.

This happens with and without the SSD connected and trying to boot from the USB drive.
 
M

mccafe

Member
I was told that it was liquid damage, but I am starting not to believe it. None of the white stickers are red, no sign of water or any corrosion on the board. Looks like a completely brand new board. I removed the keyboard connector just now and tried starting it. It does the same thing.

Am I being trolled?

Can the daughter board for the HDMI/memory card slots be disconnected for the system to run? It currently is.
 
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D

dukefawks

Administrator
You can take everything off and it will run, just fans will be on high and it may run slow. These boards have the shitty shutdown problems like 820-3662.
Make sure SMC_ONOFF is at 3.4V.
 
M

mccafe

Member
I see.

SMC_ONOFF_L is at 3.38v. Check.

Possibly a bad SMC is causing this board to fail?

EDIT: I also notice the CPU is scorching hot. Not too sure if this is normal, but the fan isn't running at full speed.
 
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D

dukefawks

Administrator
Nope, it is probably the usual 3662/3787 shut down issue. These are hopeless if that happens, sorry. Unless there is some other history to this board this one is hopeless.
 
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