Dell N7110 Missing 5V rail

[hazardus]

Hello,

I've a Dell N7110 with a missing 5V rail. The 3.3V was missing too after I replaced the KBC it came back but still no 5V.
+5V_EN1 comes from ALW_ON but nothing there. It's coming from KBC but I'm pretty sure the KBC is good. On page 36 nothing on PR166. What could this be?

Thanks.

[meritosari]

Re: Dell N7110 Missing 5V rail

check voltage PU12 pin 18 and 23

[hazardus]

Re: Dell N7110 Missing 5V rail

Nothing on 18. 3.3V on 23.

[hazardus]

Re: Dell N7110 Missing 5V rail

I removed Q26 and I checked if something pulls down the ALW_ON line from KBC. It does not present neither when Q26 was removed.
However when I turn on the bench power supply pin3 on Q26 goes down to 0V if I turn it off it goes above 4V.
I'm totally lost here. Please someone give me some advice.

[smali]

Re: Dell N7110 Missing 5V rail

how many oham on pl10 with ground?

[meritosari]

Re: Dell N7110 Missing 5V rail

Nothing on 18. 3.3V on 23.

what about pin 4 pq41?

i got problem on rt8206b last week ago, causing OVP i check gate low drive mosfet on 5v alw rails its 4v. problem solid capasitor, if measure nothing find short but lost capitance.

sorry for my bad english

[hazardus]

Re: Dell N7110 Missing 5V rail

how many oham on pl10 with ground?

26Ohm to the ground.

what about pin 4 pq41?

i got problem on rt8206b last week ago, causing OVP i check gate low drive mosfet on 5v alw rails its 4v. problem solid capasitor, if measure nothing find short but lost capitance.

sorry for my bad english

Nothing on pin 4. On PU12 missing the enable signal at the pin14(on1).
I have to find out why. Someone recommended to remove PQ48.
On the gate of PQ48 I measured 62Ohm. But nothing on ALW_ON.

[meritosari]

Re: Dell N7110 Missing 5V rail

qoute:
Someone recommended to remove PQ48.

so, thats mean if alw_on pin 2 pq48 high its current flow to ground, right?

i'm newbie too, so i learn about that

[meritosari]

Re: Dell N7110 Missing 5V rail

what about voltage on PU12?
1 ref
3 vcc
4 onldo
6 vin
7 ldo
10 out1
13 pgood1
14 on1
16 lx1
25 lx2
27 on2
28 pgood2

[sopik78]

Re: Dell N7110 Missing 5V rail

Did you solve the problem on 5V rail?

[keeney123]

Re: Dell N7110 Missing 5V rail

and what are the voltages on PQ11 with battery disconnected and adapter plugged in.