820-3115 not turning on

Yoel Ren

Member
this came in botched from another store without smc.
Replaced smc, and i got green light now., but board still not turning on.
pp5v_s5 : 5v
pp3v3_s5 : 2.9v ( strange )
ppvrtc_g3h : 2.9v ( strange too)
ppbus_G3h : 12.6v
I have tried replacing tps, but still no luck.
any pointer ? thanks..
 

Yoel Ren

Member
the whole board is cool.
u7200justtt a bittt of warm.
r7269 and r7270 is 5k ohm each.
all around u7200 and u7200 itself has been resoldered and rock solid.

all around u2600 is perfect too.
 

2informaticos

Administrator
Staff member
You cannot propely check the resistor value onboard.
If needed, play with RC/RD divider, until get correct 3V3_S5.
 

Yoel Ren

Member
hmm.
i tried to play with rc rd, at first, I wire r7270, but I got 2v.
i thought, ok, lowering resistance give me lower value, lets replace with higher rating resistor. so I gave 15k ohm resistor to r7270.
but voltage is like 200mv.
Im confused.

for r7269, from board view its connected to ground. but according to schematic, theres no ground on either pin 1/2 of r7269.
so I tried to wire it, but voltage is gone, so I replace r7269 back.
 

2informaticos

Administrator
Staff member
According to SCHEMATIC, pin 2/R7269 goes to ground through XW7201.

The formula from the schematic shows that increasing R7270 (RC) value, will increase VOUT (3V3_S5).
 

Yoel Ren

Member
hi, can we start over ?
i dont have pp3v3_s5 now, I have put everything back.
I have smc_pm_g2_en, but s5_pwrgd is 0v.
p5v3v3_reg_en is present, but pp3v3_s5_reg isnt present. is it because of missing s5 pwrgd ?
I have tried replacing u7941.
 
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2informaticos

Administrator
Staff member
S5_PWRGD is a power good signal, which will come high ONLY when 3V3_S5 is present.

Replaca R7269/70 and check all solders and traces.
 

Yoel Ren

Member
i see..
replaced r7269 and r7270 to original value. and back to square one. pp3v3_s5 is 2.9-3.0v
any advice for r7270 value ? is 100k too much ?
 

Yoel Ren

Member
THANKSSS A LOTTT!!
Pin 9 of u7200 to r7220 is actually broken, the broken trace is camouflaged so well.
you told me to check, so i have to do it with resistance mode to all trace.
when i see resistance so huge, turn out there's small crater.
i will be more careful next time, thanks a lot!!
 
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