820-2936 with 12,23V on ppbus_g3h

[jadao]

No water damage, received this board initially with no green light it was also missing U9310..
PP3v42_g3h was 3,42v SMC_BC_ACOK was also 3.4V sys_onewire and adapter_sense = 3.3V.
It turned out smc data line was shorted by isl...

Replaced ISL and got green light with ppbus_g3h at 12.23V I noticed green light come a little bit later than usual...
SMC_RESET_L is present at 3.3V.
checked U5010 and it's ok, with pp3v42_g3h = 3.42V SMC_RESET_L = 3.3 v SMC_ONOFF_L = 3.3v and 2.8V on smc_manual_rst_l, 3.3v on pin 8. smc_tpad_rst_l = 3.3V.

It looks like I will have to find another 2936 smc.

Anything else I could check before replacing SMC, Is U9310 important to put back? I know it shares data line with other components to PCH...

Thanks

 

[2informaticos]

U9310 is not involved in power on sequence.
Is used for external display port.

First check if R7000 is OK.
Also look at resistance to ground on SCL/SDA lines of battery bus; diode mode, red probe to ground.
If get more than 1% difference, remove D6950 and check again.
If still bad, remove ISL6259 and measure the values; if not good, SMC issue...
BIL connector is supposed to be disconnected.

 

[jadao]

Thanks for u9310 clarification. And sorry for the basics info i forget to tell.

Yes R7000 is 0 ohms with continuity to u7000, I can see also 3,46v on both sides and U7000-Pin13

Resistance to ground
R5280 2,611 kOhms
R5281 2,614 kOhms

Diode mode also checks ok after changing the shorted ISL
R5280 0.493
R5281 0.491

I will go for the SMC maybe a spike killed U7000 and SMC in combo...It sucks I don't have a lot from these old board, I will dig for a good SMC.

I will report.

 

[jadao]

So back to the board, Ireplaced smc, and got 12,56v on ppbus_g3h. It's turning magasfe light to orange when a battery is plugged. However board still doesn't boot (no fan spin).
I found U2800 with a small hole crack, all signal were present except PP3V3_T29. witch is total short from ground.

 

[2informaticos]

Do you get 32KHz clock output from U2800?
PM_SLP_SUS_L goes high?
What about 3V3_S5?

I recommend you change U2800; check if PP3V3_T29 is gone when U2800 removed.
If not, remove U3810 and see if board starts this way; with new U2800, of course.

 

[jadao]

3V3_S5 is present at 3.3v.
Didn't checked 32 kHz, I will check and confirm it with O-scope and new U2800. I found something like 0.6v wich I think should be more around 0,4V... I will check also PM_SLP_SUS_L.

I found diode mode on PP3V3_S0 very low 0.050. with PP3V3_T29 full short to ground 0.001 in diode mode, must be something with U3810.

I remove u3810 and will report... THANKS!

 

[jadao]

Waw this board is trash I removed U3810 and still full short on PP3V3_T29 and PP3V3_S0 with diode mode 0.050.
It looks like endless issues...

PP3V3_T29 short was caused by u3900.

injected power 3.3V on PP3V3_S0 and only j9000 area and U1800 are slighly warm nit burning at all.

PP1V05_S0 is also full short removed R7640 and confirmed short from system side...
Injected 1v05 5 amps it draws 2Amps and only U1800 and U1000 are slightly warm...
removed all power switches u4202 u3815 u3816 and caps to make sure...

Board is in S0 state but it's a nightmare... game over for this one I think, too much trouble...
thanks for the help...

 

[2informaticos]

Sometime, unsuccessful repair serves too; you gain experience!