820-2936 NO GREEN LIGHT

[Yoel Ren]

hi, this came in, clean.
ppbus is 12.2v
pp3v42 is 3.3v
but theres no green light.
I have used my known good smc in the customer board, but still no green light.
then i saw smc_bc_acok is 0.5v.
r5087 is good, i have replaced it too.
u5110 has been replaced.
diode mode of smbus_smc_bsa_scl and sda is same, at 0.484. voltage is same too.
i have make sure that continuity of r5281 and r5280 reach bottom of smc.
smc_reset_l continuity is present on bottom of smc as well.

i read this post : https://boards.rossmanngroup.com/threads/820-3115-from-no-power-to-power-then-no-power.21236/
"Is PPDCIN_G3H fluctuating between 16.6v to 16.1v rapidly on pin 1 or 2 of D7005 "
and my ppdcin is fluctuating as rossmann say, is this the cause ?

 

[2informaticos]

Do you get correct 20MHz oscillation at Y5010?
If no o-scope available, post SMC_XTAL/EXTAL DC voltage.

Should be good to try another ISL6259.

 

[Yoel Ren]

unfortunately i dont have o scope.
smc_extal is 1.6v ( diode mode 0.737 )
smc_xtal is 0v ( diode mode 0.722 )

another isl6259 is tried, but still same symptom..

 

[Yoel Ren]

just curious, but if i jump r5087, i have green light, board turn on and post.
but better take care of this the proper way.

 

[2informaticos]

Replace R5087; you can use 100-330K, instead of 470K.