820-01987

[wirelessplanet]

Board came in for no power. drawing only 5v 0 amps. i checked all the coils and large caps and found a short on ppbus_g3h. I took off f7000 and injected voltage but nothing is getting hot. (checked with flir). any suggestions on how to find the short?

 

[2informaticos]

Injecting voltage without checking for damaged secondary power supplies first???
If you injected into CPU and it has heatsink on it, that can be the reason nothing heats.
What exact voltage did you inject and which was the current indication?

What is the exact ohm resistance on PPBUS_G3H (to ground)?
Any big coil gives the same reading?

 

[wirelessplanet]

What exact voltage did you inject and which was the current indication? i send 2v 1amp
What is the exact ohm resistance on PPBUS_G3H (to ground)? .9 ohms
ive noticed shorts on the following lines,
ppbus_g3h_ssd0 (removed u9080)
ppvin_g3h_p3v3g3h (removed r5440 and short went away on that line)
ppbus_g3h_spkramp_left
ppbus_g3h_spkramp_right

no other big coils are short. L7210 and L7220 seemed a little low to me but may be good 3.2ohms.

 

[2informaticos]

3.2 ohm may be good on CPU core; you should compare with good board.

"i send 2v 1amp"
Into 0.9 ohm???
Should be more than 2A (2V divided by 0.9 ohm); if we believe in Ohm law.
Set amp limit to max before injecting; and use powerfull cables for lab PSU.