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820-3462 low ppbus no green light

Y

Yoel Ren

Member
this came in, no visible liquid damage, but whole board is dusty
ppdcin is 16.5v normal
pp3v42 present, but no green /orange light.
adapter sense up to pin 2 of j6900 is normal 3.4v,
ppbus is 1v
resistance between pin 17/18 :4 ohm
27/28 is 20 ohm
smc_reset_l is 2.8v at first,after I reball smc, now at 3.2v
should I worry about ppbus later until I get magsafe light ?
 
2informaticos

2informaticos

Administrator
Staff member
PPBUS_G3H must appear, even if no Magsafe light present.
Post ISL6259 voltages; pins 1, 2, 3, 6, 9, 12, 13, 14, 15, 17, 19, 20, 27.
 
2informaticos

2informaticos

Administrator
Staff member
"pin 1 is 0v, i look another post is at least 16.5v"
No idea what you've seen, but not true at all; 0V is perfect at pin1.

Check resistance between pins 17/18 and 27/28.
Post diode mode to ground at L7030.
Check/replace R/C7025.
 
Y

Yoel Ren

Member
resistance 17/18 : 3 ohm 27/28 20 ohm
diode mode L7030 : 0.466v
r7025 is good at 0.1 ohm
c7025 is not shorted.
 
2informaticos

2informaticos

Administrator
Staff member
"c7025 is not shorted"
Does this mean to have good capacity???

Check R/C networks from pins 5, 7, 8.
 
Y

Yoel Ren

Member
yeah good capacity, diode mode to ground on pin 1 of c7025 is 0.533v, pin 2 0.121v
r7042 : 0 ohm
r7015 : 99k ohm
r7016 : 3 kohm, all good according to schematic
 
Y

Yoel Ren

Member
i usually look for another post as reference, but low ppbus's post is too limited..
i can assure u7000 soldering is good, maybe the chip itself is bad ?
 
Y

Yoel Ren

Member
i have changed u7000 multiple times, but all same, ppbus is still at 1-1.1v.. im rather sure the problem isnt u7000 then
 
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