[SOLVED]820-00165 Short on PPBUS_G3H

[computercaverva]

Got a board in that has no signs of liquid damage, has magsafe light but no other signs of life. Found F7040 blown, replaced after checking that things around the ISL looked par for the course. Still no fan spin and the smell of something getting hot. Long story short in a rabbit hole removing anything that could possibly short the rail to ground Q3080, isloated the part of the rail from the back light, etc. Im starting to think this board may have a CPU short and that its a donor board. Resistance between pin 1 and pin 2 of L7310 and L7320 is 0.2 Ohm. Is there any hope are should I tell the client "He's Dead Jim."?

 

[dukefawks]

Resistance between pin 1 and pin 2 of L7310 and L7320 is 0.2 Ohm
Why are you measuring a coil and what were you expecting?

Inject voltage on PPBUS and see what heats up.

 

[computercaverva]

When power is injected c7056 gets hot beside the CPU.

 

[smiba]

Remove C7056 and see if that clears the short, then replace it

 

[dukefawks]

There is no C7056 in my 00165 schematic. Just rip it off, it is on PPBUS anyway and not need to replace.

 

[computercaverva]

There is no C7056 in my 00165 schematic. Just rip it off, it is on PPBUS anyway and not need to replace.

This is what I get for trying to remember component numbers without a schematic in front of me. It was C7376 when I replaced it with another cap the short was gone however it got hot with power running through it. I removed it completely and the computer turns on, is it ok to leave it off for good?

 

[smiba]

If you replaced it with another cap it quite possibly just was leftover heat from the replacement or it was also damaged.

Like duke said you can leave it off for good. Its not very important as its just one of the 8 big input capacitors.

 

[computercaverva]

Awesome! This was the first repair for a new business client I always hate the first impressions being unrepairable! This one is solved. Thanks smiba and [USER][/USER]