Asus x55a problem

[Morsus]

Hello guys.
I got an broken x55a Asus laptop. I found that these x55 laptops are not stable and die all the time. I searched high and low and found even 4 threads here on badcaps about these mobos. But unlikely no thread helped me locate my culprit. So as everyone else problem with this laptop is that when you power it on the mobo starts and after some time cpu fan starts working too (probably when heated more than room temperature) but the display stays off. Same happens with external display (via vga port). So I opened it and everything seems okay. I measured some voltages and its all 19,5,or 3V (somewhere 1.V). The thing I noticed too is that 4 caps near cpu are all short circued same as that grey block element (marked red) but the bottom cap isn't shorted. Can you at least point me out on what should I check to find the culprit? Also how can I test those 3 mosfets in the same circuit?
Here are the pictures.

[heavymachines]

Re: Asus x55a problem

Disconnect all power source including battery, press and hold power button for 30 seconds to discharge static, reconnect power source and all should be well. I had dozen of these models come to shop in last month varying issues from static buildup, to bad battery to blown mosfets not far from dc jack due to stock charger going out with a surge (Shorted itself out).




Missed the bad cap details, if you're certain that is the problem (shorted) replace em.

[heavymachines]

Re: Asus x55a problem

Of course recheck caps out of circuit. Hope your shorted data is correct. Are u using negative lead on ground by screw holes and positive lead to test both sides of cap? I would really try the static discharge hard reset first before getting down and dirty with this.

[Morsus]

Re: Asus x55a problem

Thanks for your reply.
Tried the method twice, same results. The fan starts working the leds light up but no picture on the screen or external monitor via VGA port.

[heavymachines]

Re: Asus x55a problem

Try swapping ram? laptop ram sticks go bad quite often and will do that very symptom and cause short reading....

[Morsus]

Re: Asus x55a problem

Of course recheck caps out of circuit. Hope your shorted data is correct. Are u using negative lead on ground by screw holes and positive lead to test both sides of cap? I would really try the static discharge hard reset first before getting down and dirty with this.

Oh, sorry I didn't specify. I was thinking about how they are shortened between themselves not the ground-cap. When I place any lead on the first connector on fist cap and the other lead on the last connector of the last cap I get a beep on my multimeter. I just checked what you meant and the result is the same. I get a beep on every connector (positive/negative) of the caps shortened with the ground (screw holes). Please take a look at the images. I colored blue every connector that gives a short circuit to the ground.

Edit: I tried removing ram from the board and got the same results as when it was on the board. Will try another ram module as soon as I can find it, probably tomorrow.

[heavymachines]

Re: Asus x55a problem

btw that grey coil (Choke) will read short in diode mode, normal... need to check it in ohms.

[heavymachines]

Re: Asus x55a problem

I get a beep on every connector (positive/negative) of the caps shortened with the ground (screw holes). Please take a look at the images. I colored blue every connector that gives a short circuit to the ground.

Edit: I tried removing ram from the board and got the same results as when it was on the board. Will try another ram module as soon as I can find it, probably tomorrow.[/QUOTE]



Ok looks like we got legit short. Now see if we can find schematic on mobo. Need full part numbers of motherboard.....

[Morsus]

Re: Asus x55a problem

From other topics on the same board:

https://www.google.com/url?sa=t&rct=...dEFWng&cad=rja

Also here are the pictures from my board.

Edit 1: I downloaded the packed file from the link Djosla posted but I have no idea in what program to open those files :/

Edit 2: I have just checked the resistance between the connectors of the grey coil (Choke) seems like it's 0 ohms. When I switch my multimeter to 2k it outputs 1.5 on the screen and quickly dropping on 0 ohms (second or a half of second). Same thing when I switch my multimeter to 20k just more zeros :/

Edit 3: It happens all the same on other Choke since there are two of the same size. [Added an image]

[heavymachines]

Re: Asus x55a problem

Well after looking up this thing for board numbers to find schematics no go and i couldn't find it before either when i had to replace fets. Unless somebody can please upload. But i am going to bet its one of those two ic's by those caps. Not easy to remove and check. Wish they still used sot8 package... Best done with flux and heat gun with reflow station is how i did it on the other x55a er c both very similar...

[heavymachines]

Re: Asus x55a problem

Does this match your fets?

[Morsus]

Re: Asus x55a problem

I can do that, but only tomorrow. I got a reflow station so I'll remove them. It would be great if you could just tell me how can I check them with my multimeter once i get them off
Just to be sure you are talking about these two (image) right?
Those are probably these:
https://cdn.badcaps-static.com/pdfs/...5f799ebbe8.pdf

[heavymachines]

Re: Asus x55a problem

Edit 1: I downloaded the packed file from the link Djosla posted but I have no idea in what program to open those files :/




Open it in notepad. But useless really...

[heavymachines]

Re: Asus x55a problem

Ok good, you check them like most fets, check for shorts on source and drain and gate and drain...http://mayohardware.blogspot.com/201...g-mosfets.html here is instructing how to check it in sot-8 package but same rule applies to the kind you have which is so-8 package. and it wouldn't hurt to check the surrounding caps too. Are you going to be able to put them back if good? You will need to put a small nozzle on reflow station. I would use reg iron for caps with chip quick flux works best for me anyhow..



Edit... You will check it with N channel procedure...

[heavymachines]

Re: Asus x55a problem

Have u checked for shorts with cpu removed?

[Djosla]

Re: Asus x55a problem

Edit 1: I downloaded the packed file from the link Djosla posted but I have no idea in what program to open those files :/




Open it in notepad. But useless really...

you can`t really open boardview files in notepad...Use boardview software...for this i recomend https://www.badcaps.net/forum/showpo...0&postcount=22


Nego komsija,jesi li probao bios da uprogramiras ?

[Morsus]

Re: Asus x55a problem

Have u checked for shorts with cpu removed?

I just did and the shots are gone actually.
I get short circuit only between negative lead on ground (screw hole) and positive on NEGATIVE sides of caps (all ones) and source of top two fets.
So I wont try to remove any components until I get a new processor to try it.

Djosla:
Pozdrav komso. Nisam jos pokusavao da fleshujem bios bez slike na ekranu

[heavymachines]

Re: Asus x55a problem

There you go, i would try different cpu........... and thanks for tip on board view, i have always dealt with pdf etc, never used that and quick lookup of file extension said can be viewed in notepad my bad should've looked further Thanks djolsa. Learn something new everyday.

[Morsus]

Re: Asus x55a problem

Okay, there are news on the problem.
I found another CPU, replaced it, result is exact same as with the CPU before.
I measured voltages of the suspected circuit and wrote the results on the second attachment image.

[Djosla]

Re: Asus x55a problem

Nijesi me dobro ukapirao...na programator da ga flesujes...ne diraj ostalo jer je mozda u redu...Nizak otpor moras da imas u kolu aktivnih cipova...to je normalno...