Sony Vaio VGN-N31M No Power - DEAD

[rmps]

Hi guys,

I have a Sony Vaio with Motherboard MBX-160 MS72 that have no power, no lights, nothing..

I checked pin8 of Bios Chip and it only have 0.20v ..
Power button only have 0.20v too..

What could it be? Some help?

Thanks in advance

[whaldsz]

Re: Sony Vaio VGN-N31M No Power - DEAD

1. check if you have around 19v at PR1 (DCBATOUT).
2. check PU3. It gives 3.3v to U16 (FLASH BIOS) and U15 (SIO)

[rmps]

Re: Sony Vaio VGN-N31M No Power - DEAD

PR1 have 0 volts.... :/

[spleenharvester]

Re: Sony Vaio VGN-N31M No Power - DEAD

Is PQ3 burnt up? There looks like there might be a mark at its top right corner?

[rmps]

Re: Sony Vaio VGN-N31M No Power - DEAD

Is PQ3 burnt up? There looks like there might be a mark at its top right corner?

No m8..

That´s solder paste because i´ve already replaced PQ1, PQ2 and PQ3...

[spleenharvester]

Re: Sony Vaio VGN-N31M No Power - DEAD

Ah okay, is there any schematic out?

[sorinac]

Re: Sony Vaio VGN-N31M No Power - DEAD

check pf1 fuse
and here is the schematic

[spleenharvester]

Re: Sony Vaio VGN-N31M No Power - DEAD

Definitely check PF1. Check PQ2 also.

[rmps]

Re: Sony Vaio VGN-N31M No Power - DEAD

Definitely check PF1. Check PQ2 also.

PF1 is good

PQ2
pin1- 19.86v
pin2- 19.86v
pin3- 19.86v
pin4- 19.86v
pin5- 0v
pin6- 0v
pin7- 0v
pin8- 0v

Also: this is a MS72 board, not MS70 like the schematic above.

I think this is the right schematic for this board.

Thanks in advance

[spleenharvester]

Re: Sony Vaio VGN-N31M No Power - DEAD

Right, so it appears there is a short on DCBATOUT. Here is what I would personally do:

1) Measure the resistance of pins 5/6/7/8 of PQ2. I am assuming there probably isn't a short because otherwise there'd be 0v on pins 1/2/3/4.

2) If no short is present, work your way around that diagram and try to find a short. I would personally check PD1, and PD6 first.

3) If you find a short, start removing components one by one to find the source.

You may find the MAX chip needs replacing, it's entirely possible.

EDIT: If you did find a short, I would assume either PD6, PC22 or PC24 have gone open circuit, because otherwise it would be 0v on pins 1/2/3/4 too. Someone correct me if I'm wrong.

[rmps]

Re: Sony Vaio VGN-N31M No Power - DEAD

Right, so it appears there is a short on DCBATOUT. Here is what I would personally do:

1) Measure the resistance of pins 5/6/7/8 of PQ2. I am assuming there probably isn't a short because otherwise there'd be 0v on pins 1/2/3/4.

2) If no short is present, work your way around that diagram and try to find a short. I would personally check PD1, and PD6 first.

3) If you find a short, start removing components one by one to find the source.

You may find the MAX chip needs replacing, it's entirely possible.

EDIT: If you did find a short, I would assume either PD6, PC22 or PC24 have gone open circuit, because otherwise it would be 0v on pins 1/2/3/4 too. Someone correct me if I'm wrong.

SO, i was about to measure what you´ve told me but PD6 is not present... O.o (WTF?)

Check picture:
(already replaced PC30,PC23,PC22,PC28 and PC24)

[spleenharvester]

Re: Sony Vaio VGN-N31M No Power - DEAD

That's pretty weird. Check around for other empty component pads on the board, are they tinned like that one is?

Also PC26 and PC27 have what looks to be dry joints and also a blob in between them that could migrate. Maybe worth taking a look at.

Aside from that, if the other empty pads on the board are all tinned, I'd just assume it was removed from the design for a reason and carry on without it. Especially if there is a short.

EDIT: It's right next to PC22. Is it possible you accidentally desoldered it when replacing PC22?

[rmps]

Re: Sony Vaio VGN-N31M No Power - DEAD

Dont know why but PC26 and PC27 are shorted to ground.. The dry joints means that i´ve already took them apart from the board to see if the short was still there... and it was :/

[rmps]

Re: Sony Vaio VGN-N31M No Power - DEAD

That's pretty weird. Check around for other empty component pads on the board, are they tinned like that one is?

Also PC26 and PC27 have what looks to be dry joints and also a blob in between them that could migrate. Maybe worth taking a look at.

Aside from that, if the other empty pads on the board are all tinned, I'd just assume it was removed from the design for a reason and carry on without it. Especially if there is a short.

EDIT: It's right next to PC22. Is it possible you accidentally desoldered it when replacing PC22?

No my friend... I´m preety sure that PD6 was never there.....

[spleenharvester]

Re: Sony Vaio VGN-N31M No Power - DEAD

PC26 and PC27 are on the same line as DCBATOUT. Are you able to confirm that there is a ground short on the whole of that line? On PC8 etc?

[rmps]

Re: Sony Vaio VGN-N31M No Power - DEAD

PC26 and PC27 are on the same line as DCBATOUT. Are you able to confirm that there is a ground short on the whole of that line? On PC8 etc?

As you can see on the picture, there is no PC8. But all of that is shorted..
PC16, PC15, PC14, PC8, PC13, PC4, PC5 and PC1 (All shorted to ground)
Along with PC26 and PC27 of course.

EDIT: This PQ6 seems suspicious to me. It´s an AO4606. What do u think?
EDIT 2: PQ6 pin1 and pin3 are shorted to ground too.... :/

[spleenharvester]

Re: Sony Vaio VGN-N31M No Power - DEAD

EDIT: This PQ6 seems suspicious to me. It´s an AO4606. What do u think?

We are on the same train of thought.

Test for presence of short on PC13 throughout this.

1) Remove PR1 and identify which side of its pads the short is on. As we both know, it will probably still be the DCBATOUT side.

2) Remove PQ6 and test which side of the pads the short is on, if it is still there. Afterwards, leave PQ6 removed for now.

3) If we are unlucky and the short is still there, I would personally remove PQ3 and PD1.

If the short is still closest to the DCBATOUT side with PC13 on, that narrows it down to either that row of caps, or MAX itself. As well as PC26 and PC27 don't forget.

If you still can't find the short it will likely be in another area, but we can cross that bridge if it comes to it.

EDIT: Pins 1 and 3 being shorted are to be expected.

[rmps]

Re: Sony Vaio VGN-N31M No Power - DEAD

Thank you my friend!

Will do just that! But tomorrow... Dinner time here

Thank you once again!
Regards

[spleenharvester]

Re: Sony Vaio VGN-N31M No Power - DEAD

Good luck! I get frustrated as hell when I end up having to remove components haha.

There's always the chance that something connected to DCBATOUT is shorted too, something I forgot about in my last post. But first things first.

[rmps]

Re: Sony Vaio VGN-N31M No Power - DEAD

My friend..

After removing PC1/PC4/PQ3/PD1/PC26/PC27/PQ6/PC30/PC23/PC22/PC28/PC24/PR1/PL1/PL2/PL3 and PL4 the short is still there!!

OMGGGGGG

What the hell is going on in this motherboard? Witchcraft? O.o

DAMN!