A1708 820-00840-A no power

[hgoncalves]

Hi,

I have a A1708 820-00840-A with no power.

It puls 20V from ampmeter but 0A (only board on desk).

PPBUS_G3H = 0V and seams to be shorted. It has 0.002 on diode reading and 0.4 ohm in resistance to ground.

R7020 = 20V

F7000 = 0V and 0.002 on diode reading. After lifting F7000, PPBUS_G3H remained shorted.

F8400 = 0V and seams to be ok (it has continuity). When removed F8400, the short remainded in PPBUS_G3H, and PPVIN_S0SW_LCDBKLT_F had 0.500 on diode reading)

should I inject 1V here?

Can you help?

 

[2informaticos]

Why don't check diode mode readings on the big coils first???

 

[hgoncalves]

Hi,

I don't have any other good board to compared them, but I think they are in normal values:

Diode readings:

L7670 = 0.440
L7690 = 0.382
L8410 = 0.833 (maybe to high?)
L7030 = 0.496
L7730 = 0.255
L7430 = 0.004
L7410 = 0.004
L7420 = 0.004
L7210 = 0.009
L7220 = 0.009
L7370 = 0.013
L8060 = 0.067
L7900 = 0.081
L7960 = 0.107
L8030 = 0.243

 

[2informaticos]

Then must be a bad capacitor.
If you didn't escape any coil, then is safe to inject voltage.
As always, start with just 1V
Set amp limit to max first.

 

[hgoncalves]

TKS.

The culprit was C8187.

Now it boots, but it dosen't charge the battery.

The battery is recognized is OSX, the status is "Normal", but it says "Not charging" and stays at 0%.

The mac only puls around 0.500A from the charger

 

[2informaticos]

Tested with known good battery?