820-3437-B orange light - no fan spin

[Ncrtech]

First time post here - I'm relatively new at board repair in general.

As the title says, I've got an 820-3437-B that won't power on. I get an orange light on the charger and no fan spin.

With a visual inspection, I found corrosion on U1900 and components in close proximity.

I have tried quite a few things, but since I'm not even sure that I could remember all of the things I've tried so far, I'm going to just list out where things stand currently, things that I know of at least.

Voltage readings:
(In no certain order)
PPBUS_G3H - 8.57V
PP3V42_G3H - 3.42V
PP5V_S4RS3 at L7520 - 0.89V
PP3V3_S5 at R5590 Pin 1 - 3.34V
L7310 - 0V

Voltage readings around U1900:
PPVRTC_G3H - C1910 - 3.41V
PP3V3_S3 - R2040 - 3.33V
PP3V3_S0 - R2041 - 1.78V

Other possibly related voltage readings:

PM_SLP_S4_L - R8179 - 0.80V
S4_PWR_EN - R8177 - 0.00V
P5VS4RS3_EN - R8176 - 0.80V
PM_SLP_S5_L - R8115 - 0.00V
SMC_S4_WAKESRC_EN - U8170 - 0.00V



Also, in case it's relevant, the CPU gets hot. I've tested and tried a lot of different things, but since I am new at this, please don't assume that I haven't overlooked something.
Any help and advice will be greatly appreciated!


*Edit** Reading over this again, this looks like a total plz bro type of post which wasn't my intention. I have looked up, or at least attempted to figure out, where the missing/low lines originate and how the different rails get created. My brain is just complete mush right now from working on this for at least 6-7 hours so far.

 

[2informaticos]

First of all, welcome to the forum!

"PM_SLP_S4_L - R8179 - 0.80V
PP3V3_S3 - R2040 - 3.33V"
Really strange, as 3V3_S3 requires PM_SLP_S4_L to be high.
Is U8010 shorted input-output?

Do you get any voltage at L7430 and L7820?

 

[Ncrtech]

First of all, welcome to the forum!

"PM_SLP_S4_L - R8179 - 0.80V
PP3V3_S3 - R2040 - 3.33V"
Really strange, as 3V3_S3 requires PM_SLP_S4_L to be high.
Is U8010 shorted input-output?

Do you get any voltage at L7430 and L7820?

Thanks for the reply!

I do not get any voltage at either L7430 or L7820.

As far as U8010 goes, before removing it, I probed all of the surrounding connecting components in diode mode and all gave what I would consider a normal reading. I then went to the other nearby and possibly related/relevant mosfet's and did the same, and near U8030, PP3V3_S0_FET_R gave a very low diode mode reading, somewhere around .040, and PP3V3_S5 was .025. So I removed U8030 and PP3V3_S0_FET_R now reads 0.366, but PP3V3_S5 still reads .025. I still didn't remove U8010 yet until I told you what I found with this, to see if you wanted me to go ahead and remove it for sure.

 

[2informaticos]

0.025 is to low for 3V3_S5.
You said to have correct 3V3_S3, so U8010 should be good.
Unless is not shorted I-O.
Something else may be bad on 3V3_S5 rail.

Please write directly on the reply box.
I don't see any reason to quote an entire post, visible few centimeters above...