820-3787-A Does not turn on or charge

[MikeyD]

820-3787-A

-Green light on charger but then turns into Orange Light
-No boot, no fan spin

-Not sure of what each rail does yet as I’m pretty new to this
-Also not sure of the different “states” like S0, S3, S5, etc.
-So I went to the schematics and measured a handful of rails and I’m hoping someone can point me in the right direction.


PPBUS_G3H - 12.58V
PPVIN_S5_HS_COMPUTING_ISNS - 12.58V
PPVIN_S5_HS_GPU_ISNS - 12.58V
PPVIN_S5_HS_OTHER3V3_ISNS - 12.58V
PPVIN_S5_HS_OTHER5V_ISNS - 12.58V

PP20V_DCIN_CONN_R - 16.4V (should be 20V)
PP20V_DCIN_FUSE - 16.6V (should be 20V)

PP3V42_G3H - 3.4V
PP3V42_G3H_SMC_SPVSR - 3.4V
PPVRTC_G3H - 2.58V (should be 3.42)

PP5V_S5 - 0.9V (should be 5V)
PP5V_S4 - 0V (should be 5V)
PP5V_S3 - 0V (should be 5V)
PP5V_S0 - 0V (should be 5V)

PP3V3_S5 - 2.5V (should be 3.3)
PP3V3_S4 - 0V (should be 3.3)
PP3V3_SUS - 2.58V (should be 3.3)
PP3V3_S3 - 0V (should be 3.3)
PP3V3_S0 - 0V (should be 3.3)


thanks in advance for any help

 

[2informaticos]

First of all, welcome to the forum!

"PP20V_DCIN_FUSE - 16.6V (should be 20V)"
Do NOT make wrong assumptions so easy!
I bet you are not using 85W charger and this is a good reason the board doesn't turn on.
Test with original charger and report back.

BTW, do not make so many measurements in the same power rail; names change a bit, still the same rail in fact.

 

[MikeyD]

Hi and thanks for responding!

I was not making assumptions, sorry. I was just listing what the schematic said. Trying to be thorough with the info I provided.
Thanks for the measurement tip too, like I said, a little new to this, so I wasn't 100% sure if the rails were related. I thought they might be, but wanted to be thorough.

The charger is an 85W actually. (which is what my friend told me was the original when he asked me to look at his computer lol)

 

[MikeyD]

60W charger (I happen to have one laying around. not sure if this the original type. I do have a DPS I can hook up if you think it will help)



PPBUS_G3H - 12.58V
PPVIN_S5_HS_COMPUTING_ISNS - 12.58V

PP20V_DCIN_FUSE - 16.5V

PP3V42_G3H - 3.4V
PPVRTC_G3H - 3.4V

PP5V_S5 - 0.9V
PP3V3_S5 - 1.28V
PP3V3_S4 - 0V
PP3V3_SUS - 0V
PP3V3_S3 - 0V
PP3V3_S0 - 0V

 

[2informaticos]

This board requires 85W charger.
It will not turn on with 45/60W charger alone; unless battery is connected and has some charge.

 

[MikeyD]

oh I'm sorry I misread your original comment, the original measurements are from an 85W charger

 

[2informaticos]

Post basic voltages of U7501 chip; pins 23, 12, 13, 22, 29, 21.
Also check diode mode to ground at all big coils.