820-3536-A Green/Orange Light, No Power.

[gcain]

Customer said it just stopped working (hehe!)

Opened it up, filthy, so I'm guessing a short burnt something.


Okay, PPBUS_G3H Sits at 12.59v for a few moments then drops to 12.12 then back up...

I traced it along the rail and reached Q7130, pin 6 is going up and down like crazy.... This connects to U7100:in21 which is also going up and down.

Does Q7130 feed power /into/ U&100:in21?

This would mean Q7130 is faulty right?

 

[dukefawks]

Remove F7140 and see if 12.6V is stable.

 

[gcain]

Once F7410 is removed Pin 1 delivers a stable 12.57v.
I took a measurement from a few different points on the Pin 1 side.

 

[gcain]

Did we just break the rail into two segments for isolation, or is the F7140 faulty?

 

[dukefawks]

The board is trying to turn on, this is when PPBUS drops to 12.12V. Is CPU Vcore coming on? Any shorts on any of the coils?

 

[gcain]

Is CPU Vcore coming on? Any shorts on any of the coils?

PP5V_S0 was fluctuating so I was measuring around, and suddenly the fan turned on...

Reassembled the machine and it boots every time now. Take the wins when you get them I guess.