820-00165 power issue

[jgraffis]

working on a 820-00165 that was working yesterday just fine, left it plugged in to charge overnight and now no green light on charger.
pp3v43_g3h is present
smc_bc_acok is present
ppubus_g3h is low at 8.13v
smc_rest_L is way low at 1.014v
r5100 30koms

I'm thinking I've got a bad smc, even though I've replace it already.
any ideas?

 

[PhilipC]

if SMC_RESET_L is low then smc wont turn on, so not a bad SMC. check SMC_RESET_L resistance to gnd and U5110 for any peculiarities

 

[jgraffis]

resistance to ground on pin5 of u5110 0.466kohms. pin4 smc_manual_rst_L is kinda strange at 2.7v, pin 8 is at 3.3v, pin6 is 3.41v, pin1 and pin3 at 3.42v, pin 7 at 3.42v

 

[dukefawks]

Crap under SMC, SMC itself is most likely fine.

 

[jgraffis]

i recalled the smc to only end up with the same issue. i ordered a donor board to replace the SMC, then got another one of these that came in with liquid damage.. so i fixed it got it running but fans on high. took that SMC off and put on this board, now the machine turns on and runs but fan on high i ran the diagnostics and had a couple issues show up( see picture). i guessing i probably have a bad smc from the second board.

does this sound right?

 

[jgraffis]

No Title

 

[nate8organic]

I have seen the same thing and it did end up being the smc, also double check the solder job is good on it sometimes the balls are just not seating good.

 

[dukefawks]

Problem on SMBUS_SMC_1_S0_SDA / SCL. Crap in J4002, bad SMC/soldering are the 2 most likely. Could be anything connected to this bus though.

 

[jgraffis]

i did check j4002 really good under microscope. i just thinking that the same fan spin issue on 2 machines with the same SMC chip is kinda a common denominator. but won't know for sure until donor board arrives and hopefully has a good SMC.

thanks for the help guys. I'll keep you posted.