820-2879 one beep

[OndrejT]

Heya guys

I have this board 820-2879 .When I bought it boot up once and die. I mean literals just say good bye and never start up again. Except annoying beep

I opened it there was some funny paper on the RAM but well it doesn't charge battery from start. So I decide first work on it and change isl625 now I am stuck with this RAM problem. On L7330 is 0.22 V
I changed already u7300 twice and still same issue. I was thinking to change Q7330 as a start point but that mos look OK. Any advice where to start?

 

[2informaticos]

Post first diode mode at L7330, red probe to ground.
Also post some voltages for U7300; pins 10, 11, 14, 15.

 

[OndrejT]

So L7330 on diode mode 0.270

pin

10:3.30
11:3,28
14:5
15:5

I know I said Q7330 look ok but pin 3-4 should not have 0.002 on diode mode, right? Its a stupid question but I rather ask and be stupid a minute that stay stupid

 

[2informaticos]

"pin 3-4 should not have 0.002 on diode mode, right?"
Not really true.
If U7300 detects a problem, it will short G-S of Q7330, to avoid any output voltage.
You can remove Q7330 and see if is short indeed.

Check all components and traces around U7300.
Change it, if nothing strange found.