SONY VPC Series DA0HK2MB6E0 dead...NEED HELP

[loser18]

OK...

I've got QUANTA HK2 (DA0HK2MB6E0) which is completely dead...
I'm stuck at PU9 (PM6686TR) as don't have DH2 voltage from pin26...

As far as I understand:

-VIN comes to pin6 (got 19V)
-that should activate EN_LDO (got 5V)
-EN_LDO should go to LDO (got 5V)
-also should activate EN2 (got 3.6V)
-& finally EN2 should activate DH2 (got 0V) & should have 3V+ which should activate LX2 and then go to SIO...


Am I wrong???
Any ideas what else to check???
These Sandy Bridge mobos are so complicated...So many voltages


I'm attaching schematic...this one is for HK1 (can't find for HK2), but at least the charging and 3&5V circuits looks the same...

ALSO NOTICED THAT PR275 & PC191 IS MISSING!!!

[atsio]

Re: SONY VPC Series DA0HK2MB6E0 dead...NEED HELP

Check resistence to ground on PL13 without power adapter plugged in.

[loser18]

Re: SONY VPC Series DA0HK2MB6E0 dead...NEED HELP

Check resistence to ground on PL13 without power adapter plugged in.

THX for response...

It's not shorted...
Checked all the coils & they're OK...(PL7 & PL8 beeps but shows 1 & 10 ohms)
Short is only under 0.5? isn't it?

[atsio]

Re: SONY VPC Series DA0HK2MB6E0 dead...NEED HELP

No

[lezsimply]

Re: SONY VPC Series DA0HK2MB6E0 dead...NEED HELP

002 and 001 is shorted I think.

[atsio]

Re: SONY VPC Series DA0HK2MB6E0 dead...NEED HELP

Usually the 3.3v rail has high resistance. A relative low resistance i.e. 20 Ohm, might point you there is a problem somewhere on the rail.

[loser18]

Re: SONY VPC Series DA0HK2MB6E0 dead...NEED HELP

Ok...

Think some idiot have done reflow on GPU & NORTHBRIDGE...(didn't even bother to remove epoxy)
There's flux all over the board...he tried to clean that,but I'm not blind...
Will reball both chips and will post results...
Really wondering why people are touching things they don't understand...

[loser18]

Re: SONY VPC Series DA0HK2MB6E0 dead...NEED HELP

Also would I have S5, S4 & S3 voltages without CPU (or if CPU's faulty) as GMCH is a part of the CPU in SandyBridge???????

[atsio]

Re: SONY VPC Series DA0HK2MB6E0 dead...NEED HELP

Yes

[loser18]

Re: SONY VPC Series DA0HK2MB6E0 dead...NEED HELP

OK...

A bit of progress...
Found spare PM6686TR, replaced & now I've got 3V, so obviously there was problem with chip itself...Now it turns on but cuts off after few sec...
Took off PL7 & PL8 and they're both shorted on right side, so will reball U16 & VU4...

[loser18]

Re: SONY VPC Series DA0HK2MB6E0 dead...NEED HELP

OK...

Desoldered both chips & both shorts gone...
However don't have stencil for northbridge so probably just leave it for spare components as got other things going on...

THX to everyone for replies...(maybe when i'll have some more spare time, i'll order stencil)