820-3115 ppbus 12.3v

[Yoel Ren]

Hi, ,this board came in with corrosion near smc and thunderbolt ic, there's a short on ppbus_g3h near u6901, at the thunderbolt stuff, anyway , i clean the corrosion and dig out the short, ppbus came in at 12.3v
I already test the smc at known good board, and i know the smc is good, i also changed isl, but ppbus still 12.3v
pp3v42 is good at 3.42, but smc_bc_acok is low at u7000 = around 2v
but at u6901, smc bc acok isnt present, should i jump smc bc acok from isl to u6901 ? im afraid the short i dig is breaking the trace from isl to u6901

 

[2informaticos]

You can bypass SMC_BC_ACOK trace, if broken.
However, it is not the reason for incorrect PPBUS_G3H.

Check diode mode and voltage on SCL/SDA lines of battery bus.
Test w/ and w/o BIL connected.

 

[Yoel Ren]

no need to test without bil because i still test it outside the chassis.
diode mode 0.452 sda
0.230 scl, i changed d6950, now sda scl is 460 452, looks good.
smc bc acok at u6901 has 2.8v now, and i have green light. but ppbus still 12.3v

 

[2informaticos]

Did you check continuity to SCL/SDA pads underneath SMC?
Change again ISL6259 and be sure R7000 is good.