ASUS u31sd LAPTOP WILL NOT TURN ON

[heavymachines]

Re: ASUS u31sd LAPTOP WILL NOT TURN ON

There's no white dot in what you have circled in picture the dot to the right of the pink line is solder or a pin from the other side of the board. My DMM doesn't have a diode mode. I have another DMM with auto range

well i guess we will go by the white line as reference to pin 1... and take pic's of the 2 dmm you have so i and others can see what all it has....

[CR Designs]

Re: ASUS u31sd LAPTOP WILL NOT TURN ON

OK , Here we go I used my Dmm with auto range. I'm asuming the thick white line is pin 1. This is how it read

1 & 8 = 191
1 & 7 =189
1 & 6 =185
1 & 5 = 187

Do these look right?

[heavymachines]

Re: ASUS u31sd LAPTOP WILL NOT TURN ON

OK , Here we go I used my Dmm with auto range. I'm asuming the thick white line is pin 1. This is how it read

1 & 8 = 191
1 & 7 =189
1 & 6 =185
1 & 5 = 187

Do these look right?

much better now now do pin 2 to the other 4 and pin 3 etc if no open or short readings we will assume this fet is ok


or super high ohms.....

[CR Designs]

Re: ASUS u31sd LAPTOP WILL NOT TURN ON

Here's my DMM pictures

[CR Designs]

Re: ASUS u31sd LAPTOP WILL NOT TURN ON

Here's a picture of back of board for parts number

[CR Designs]

Re: ASUS u31sd LAPTOP WILL NOT TURN ON

Here's another number from the back of the board

[heavymachines]

Re: ASUS u31sd LAPTOP WILL NOT TURN ON

you do indeed have diode test....

[heavymachines]

Re: ASUS u31sd LAPTOP WILL NOT TURN ON

Here's a picture of back of board for parts number

thank you now i can go hunting.... not that i have not been but came up empty...

[heavymachines]

Re: ASUS u31sd LAPTOP WILL NOT TURN ON

you do indeed have diode test....

and to add to that the ohm range selection is is used for corresponding resistors etc.... however in most ic's you will use 200k or 200 ohm depending on what it is but 200k is most common.... and diode mode has helped me as well in past especially for doing continuity tests diode mode is best bar none but have seen people use 200ohm range as well like fuses for example but for broken connection or tracing diode mode is what you want......


so with that dmm testing mosfet use 200k ....

[opamp]

Re: ASUS u31sd LAPTOP WILL NOT TURN ON

opamp can you find data sheet on this board? i am having no luck...



please double check the motherboard part/model number to aid us in finding a darn schematic for this beast... gonna do some research on this and see if i can find anything and if the part/model number is wrong we will never find it....


need to see how this thing is set up if no luck still after hunting for schematic , i will have you do some live tests but let me research and study the pics of board so i can map out rough idea how this board is wired up...

if we find schematic that would eliminate alot of guess work....

I couldn't find it.

[heavymachines]

Re: ASUS u31sd LAPTOP WILL NOT TURN ON

I couldn't find it.

thanks for trying i have not given up just yet....

[CR Designs]

Re: ASUS u31sd LAPTOP WILL NOT TURN ON

Here's the other readings with the auto range.
2 & 8 = 235
2 & 7 = 207
2 & 6 =202
2 & 5 = 202

3 & 8 = 203
3 & 7 =204
3 & 6 =204
3 & 5 = 202

4 & 8 =314
4 & 7 =372
4 & 6 = 306
4 & 5 = 301

[CR Designs]

Re: ASUS u31sd LAPTOP WILL NOT TURN ON

Heavymachines,
Thank you for all the time and help !!

[heavymachines]

Re: ASUS u31sd LAPTOP WILL NOT TURN ON

Here's the other readings with the auto range.
2 & 8 = 235
2 & 7 = 207
2 & 6 =202
2 & 5 = 202

3 & 8 = 203
3 & 7 =204
3 & 6 =204
3 & 5 = 202

4 & 8 =314
4 & 7 =372
4 & 6 = 306
4 & 5 = 301

looks within reason...gonna study and try to map out via pic's ... it looks grim for any kind of schematics.... anyhow i am gonna make some diagram and may ask for certain ic part numbers... so i can get better idea how this board works..... even thou that can be tricky since it is not in front of me but lets see if we can find the offending part...


in meantime you can put ic back on, go ahead and feel free to put heat sink back on and do live power test on bench and very carefully!!!!

see if you can trace from dc jack to where power stops to parts of board and if you find a dead area follow back towards dc jack where "dead" voltage ends to possible ic or diode or whatever,



pay attention to traces they give you good hints how to track back towards dc jack ... no hdd and display makes it sound like chipset grapics or cpu is getting nothing so a large portion of board will/should have no power.

you can test if cpu is getting power by the coils or directly under cpu socket, called v core test.. check around see if anything is obvious...

also feel around OR use laser thermometer to see what is room temp and warm or even hot just don't put finger on traces..er bare solder joints etc..

if heat sink stays cold then there is a really big portion not getting power....

[CR Designs]

Re: ASUS u31sd LAPTOP WILL NOT TURN ON

What should i have the DMM set to for live test?

[heavymachines]

Re: ASUS u31sd LAPTOP WILL NOT TURN ON

DC current 20 volts ...

[CR Designs]

Re: ASUS u31sd LAPTOP WILL NOT TURN ON

When I was testing the 8 pin fet on some of them the numbers would not hold,like at 200 for example. The number would keep going up like 200,201,203,204. does this mean any thing?

[heavymachines]

Re: ASUS u31sd LAPTOP WILL NOT TURN ON

When I was testing the 8 pin fet on some of them the numbers would not hold,like at 200 for example. The number would keep going up like 200,201,203,204. does this mean any thing?

it's fine that's normal..within reason however best way to test it is breadboard..but you can check it if its receiving voltage and has power input on all source and output all 4 drains but risky, slip up and it will go,but you put positive probe on pin one and neg probe on all 4 drains and take reading on dc 20 volts if all the drains are outputting reasonable voltage should be fine.

however some mosfets have a g pin and some cases a dummy pin on drain side that does nothing but since we can't find a data sheet on this mosfet we can't be for sure 100%....

[CR Designs]

Re: ASUS u31sd LAPTOP WILL NOT TURN ON

I don't think I will try the breadboard test to risky. going to put the heat sink back on and do some tests

[heavymachines]

Re: ASUS u31sd LAPTOP WILL NOT TURN ON

I don't think I will try the breadboard test to risky. going to put the heat sink back on and do some tests

do you have a breadboard?