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820-3115 3v3_s5 short to ground

Gmorb

Gmorb

Member
so 3v3_s5 seems to be shorted to ground i get a beep on my meter but when i inject voltage my power supply doesnt helkp me find it. must be too small of a short to be detected? what other tricks can i use?
 
2informaticos

2informaticos

Administrator
Staff member
Beep is not equal short.
Which is the exact value, on diode scale; red probe to ground, also black to ground.
Usual DC multimeters beep until 060-075, which is not short at all...

Post PPBUS_G3H and 3V42 voltage.
Do you get magsafe light?
 
Gmorb

Gmorb

Member
ppbus_g3h and 3v42 are present with a green light on charger.

on 3v3_s5 i get a beep at 23ohm and dropping

and on diode mode i get 0.013v on 3v3_s5
 
2informaticos

2informaticos

Administrator
Staff member
That is low value, but insufficient to heat anything if inject voltage.
Confirm you are NOT measuring diode scale on powered board.
Also remember, always wait 15-20s after power removed, before do any continuity measure on board...
 
J

JohnB8812

New member
Yeah as 2informaticos said disconnect power for 15-20 seconds then measure resistance to ground on 3v3_S5 again without power applied. If it's still short, inject 3.3 volts into that line. There should absolutely be current draw on a low resistance short might be hard to find it. You can increase amperage to 4 or 5 amps if you power supply allows it.
 
Gmorb

Gmorb

Member
i was able to find some shorted components by leaving magsafe on while injecting voltage i replaced a couple components that went to the same line now i do get voltage on 3v3_s5 but it fluctuates a lot. it goes as far back as r6990 on pin 2. Replaced d6990 but no change r6990 is at proper resistance no change.

removed smc but i still get fluctuation. bad pch?

any further ideas?
 
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