Please ignore the red circle in the pics. I stole it from the internet.
This board was pulled from a working unit and tested for a week before I sold it on ebay.
It was returned saying that it "worked for 10 minutes and died"
I found the main 8.5v power rail to be 2.15v. Not shorted. Same diode mode reading as the good board.
On the good board if you measure the coil with an Oscope you can see the 15v pulsation on one side of the coil and a flat 8.5v on the other side.
On the bad board it is a flat 2.15v on both sides of coil, no pulsation. It seems like the full 15v is not making it to this area of the board for whatever reason and it's not even attempting to pulse the voltage.
But right next to this area is the 3.3v standby rail area and it is working on both boards which also uses the 15v rail. I can see the 15v being chopped up into a smooth 3.3v, even on the bad board, so the 15v rail is present on the board but just not able to power the 8.5v rail.
At least that's what my amateur brain is telling me.
Not sure how to proceed since there are no schematics... Any idea of what could be happening?
This board was pulled from a working unit and tested for a week before I sold it on ebay.
It was returned saying that it "worked for 10 minutes and died"
I found the main 8.5v power rail to be 2.15v. Not shorted. Same diode mode reading as the good board.
On the good board if you measure the coil with an Oscope you can see the 15v pulsation on one side of the coil and a flat 8.5v on the other side.
On the bad board it is a flat 2.15v on both sides of coil, no pulsation. It seems like the full 15v is not making it to this area of the board for whatever reason and it's not even attempting to pulse the voltage.
But right next to this area is the 3.3v standby rail area and it is working on both boards which also uses the 15v rail. I can see the 15v being chopped up into a smooth 3.3v, even on the bad board, so the 15v rail is present on the board but just not able to power the 8.5v rail.
At least that's what my amateur brain is telling me.
Not sure how to proceed since there are no schematics... Any idea of what could be happening?
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