[SOLVED]Dell motherboard (LA-910aP) no power troubleshooting

[dominicM]

I have a dell LA-910aP motherboard with no signs of life. It was liquid damaged. I get 19V on the DCIn and even 19V, 5V and 3V on the battery controller (PU100). I cant seem to find where the issue lies. It's difficult to trace as there is no pcb layout available. What is the likely cause? What would be fists things to check? What are the logical steps to take to attempt to find the issue? There is no power draw at the wall and no voltage beyond the dcin area as afar as I can tell. Same with or without battery. No visible damage after liquid cleaned. Any suggestions or tips appreciated.

Datasheet:
http://kythuatphancung.vn/uploads/download/b2f74_Compal_LA-9104P_VAW00_Inspiron_3521.pdf

[wraper]

What is the likely cause?

With liquid damage it could be basically anything.

[Armadillo]

The liquid may be salty conductive, wash, scrub again and dry again.

[dominicM]

I realise water damage can damage almost any part of the motherboard but wouldn't the fact that there is no power past a certain point narrow the cause a little? Aren't some components more or less likely to to fail in this manner than others? I already did wash with distilled water prior to asking but issue is exactly the same as before. If something is conductive wouldn't it normally cause short-circuits? To me it would seem to narrow any bridges so certain components but I don't know specifically which ones.

[Armadillo]

I realise water damage can damage almost any part of the motherboard but wouldn't the fact that there is no power past a certain point narrow the cause a little? Aren't some components more or less likely to to fail in this manner than others? I already did wash with distilled water prior to asking but issue is exactly the same as before. If something is conductive wouldn't it normally cause short-circuits?

Example reset Pin, if the voltage don't rise to a start up level, the micro don't even start and appeared completed dead.
Or protection circuit activated etc... layer of conductive salt cannot be wash by just distilled water. What kind of water damaged is that? soda, coke ?
Plug in a POST diagnostic card.

[dominicM]

I realise water damage can damage almost any part of the motherboard but wouldn't the fact that there is no power past a certain point narrow the cause a little? Aren't some components more or less likely to to fail in this manner than others? I already did wash with distilled water prior to asking but issue is exactly the same as before. If something is conductive wouldn't it normally cause short-circuits?

Example reset Pin, if the voltage don't rise to a start up level, the micro don't even start and appeared completed dead.
Or protection circuit activated etc... layer of conductive salt cannot be wash by just distilled water. What kind of water damaged is that? soda, coke ?
Plug in a POST diagnostic card.

This is a laptop so no PCI slot. There is also no power on most of the motherboard so it wouldn't work anyways. I only get voltage around dcin and battery controller. There is also no voltage on the power button pcb connector.+

Not sure what liquid it was, could be soda, beer or something like it.

[Armadillo]

This is a laptop so no PCI slot. There is also no power on most of the motherboard so it wouldn't work anyways. I only get voltage around dcin and battery controller. There is also no voltage on the power button pcb connector.+

Not sure what liquid it was, could be soda, beer or something like it.

There are the mini PCI-E bus, the LPC bus etc...

See picture.

[dominicM]

This is a laptop so no PCI slot. There is also no power on most of the motherboard so it wouldn't work anyways. I only get voltage around dcin and battery controller. There is also no voltage on the power button pcb connector.+

Not sure what liquid it was, could be soda, beer or something like it.

There are the mini PCI-E bus, the LPC bus etc...

See picture.

True but like I said it's no use as there is no voltage apart from close to dcin and no voltage at the power on button and you can't have POST when power on button is not functional.

[Armadillo]

You can find the shorts by using a thermal imager.
Maybe some can advise you the feel method.

[Rbastler]

Or pour alcohol over the various parts of the circuit, and look for the component, where it evaporates the quickest.

[dominicM]

You can find the shorts by using a thermal imager.
Maybe some can advise you the feel method.

Like I already said there is no short circuit, there is ZERO power draw from a power supply.

[khaahk]

PU100 needs to get DCIN, ACIN should be logical high,
PQ100 and 101 should be opened to let adapter voltage to B+
PU200 should get give REF VREG3 and VREG5 when EN is logical high
KBC needs to have 3.3 ALW power on pin 9,22 etc.

and KB9012 needs to be externally programmed if changed on this mainboard.

[dominicM]

PU100 needs to get DCIN, ACIN should be logical high,
PQ100 and 101 should be opened to let adapter voltage to B+
PU200 should get give REF VREG3 and VREG5 when EN is logical high
KBC needs to have 3.3 ALW power on pin 9,22 etc.

and KB9012 needs to be externally programmed if changed on this mainboard.

I came back to this eventually and followed your suggestions. It turned out to be PU200. VIN pad was corroded, running a wire fixed the issue. Thank you!