Re: Help me repair this UX305 motherboard please
Thanks SMDFlea for your advice.
Here in France repair shops don't move the finger for this kind of job. Anyway it's fine it would be an opportunity to learn. Learning is always a good thing.
Thank you Steve, I downloaded the chip datasheet, here is a screenshot of the pins and their functions. The chip is on the way from China to France, I'll update the thread as soon as I will have finished soldering it, hopefully it solves the issue....
Clinteastwood1
Member
Last Activity: 04-20-2021, 09:33 AM
Joined: 04-02-2021
Location: Grenoble
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Re: Help me repair this UX305 motherboard please
I bought it from ali I suppose they are the same.Leave a comment:
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Re: Help me repair this UX305 motherboard please
Not the elon musk's one at least
If you have one to advice me please let me know, or I'll buy one from Amazon considering the reviews. Not to expensive though since it will be for a one time use.
This guy on yt even replace this kind of chip without any air gun, only zooming with his phone
[url]https://youtu.be/ljyGMOi5JPo[/url]
My chip ref is something like "1285a tp 5c8 a3sh", I found similar chips but the end of the ref isn't exactly the same, I guess my chip is a "TPS51285A"...Last edited by Clinteastwood1; 04-06-2021, 01:32 PM.Leave a comment:
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Re: Help me repair this UX305 motherboard please
I've watched videos on YouTube haha.
I'm gonna buy an air gun, I already have a microscope, a soldering iron, and flux, so it should be fine. I will train myself on another old motherbord first.Last edited by Clinteastwood1; 04-06-2021, 09:48 AM.Leave a comment:
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Re: Help me repair this UX305 motherboard please
I made the alcohol test and the only chip on which alcohol evaporates very fast is this 3/5v regulator. I tested all the chips on the board and coils and mosfets and other components this is the only one causing the alcohol to evaporate in a heart beat.
Is there something else could test? Or I can replace this chip and hope for the best...
These chips are very tiny compared to the others, it won't be easy I should probably buy a dozen of them just in case
Last edited by Clinteastwood1; 04-06-2021, 09:10 AM.Leave a comment:
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Re: Help me repair this UX305 motherboard please
Mate this tut is magic thank you !!!
I don't have any compressed air right now but seen in the comments that you could achieve the same with gas lighter oil or isopropyl alcohol, since I have both I'm gonna test it this way.
Before doing it (I'm not at home right now) and since this area on my board is very hot, couldnt we just conclude it's the chip you circled in yellow which is faulty, since coils don't get faulty, right?
And 2nd question, this chips reads "1285a tp 5c8 a3sh" do you know if...Last edited by Clinteastwood1; 04-05-2021, 05:21 PM.Leave a comment:
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Re: Help me repair this UX305 motherboard please
Thank you very much for the link SMDFlea I'm sure it will help me avoid desoldering mosfets for nothing. I hope I will be able to find my motherboard's problem too, thanks again
Edit: thanks to your link I realized the diode mode has to be used taking into account the sense of the measure. So I took new measures and my mosfets are all fine.
Now with this new information i hope someone here can help diagnose the board.
Here are my last mesures in the 3v/5v area (hot zone)...Last edited by Clinteastwood1; 04-05-2021, 09:59 AM.Leave a comment:
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Re: Is this mosfet dead? Strange behavior
This thread was confusing enough with all my measures and posts I don't think it was a good move adding the mosfet measuring question, this thread is already overloaded I think and nobody still participate to it...
Ok thanks for your reply mate, if I desolder it I will replace it straight away no need to test it
I am going to replace all the mosfets on my board i guess, because I'm afraid I won't be able to troubleshoot it
Cheers...Leave a comment:
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Is this mosfet dead? Strange behavior
Hi,
I am trying to troubleshoot a laptop's motherboard, I measured the resistance of the 2 entry mosfets, and the second one seems to have a weird behavior.
As a matter of fact, it has an infinite resistance (meaning it's dead, right?) but when I measure its voltage it shows 19v as the first one, as if it was fine...
So is it dead or my method to detect dead mosfets is crap? ( I tried with the diode mode of my multimeter, it also shows there is a discontinuity)
Thanks for your help guys....Last edited by Clinteastwood1; 04-05-2021, 07:49 AM.Leave a comment:
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Re: Help me repair this UX305 motherboard please
Hi Mon2 thanks for your help. I took some measures as per your suggestions. This time I took measures for all the bios chip pins to avoid confusion. Also for coils.
This area around the coils becomes very hot after a short moment.
Thanks I hope it helps...Last edited by Clinteastwood1; 04-05-2021, 07:21 AM.Leave a comment:
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Re: Help me repair this UX305 motherboard please
Little mistake sorry, pin 8 of winbond bios chip is not the right one, it's the first one at the top and it reads 1v (it's pin 5 that shows 0.28v).
It should read 3.3v I think so there is problem. Is this chip dead?Last edited by Clinteastwood1; 04-04-2021, 03:46 PM.Leave a comment:
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Re: Help me repair this UX305 motherboard please
Ok some people told me it's not reliable to use the ohmmeter to test mosfets so I took all the measures again in diode mode (testing random pins of the mosfets side by side). Please look at the pic below.
Red circles = faulty mosfets
Green circles=good mosfets
Yellow area = slightly hotter than the rest of the board
I really hope you can help me because I really do need this laptop
...
Last edited by Clinteastwood1; 04-04-2021, 09:38 AM.Leave a comment:
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Re: Help me repair this UX305 motherboard please
Thanks techtiger for coming back helping me.
- Keyboard pin 5 = 3.3v
- WINBOND : pin 1 : 0.11v, pin 8 : 0.28v
- the 2 Gragy Coils middle of the Bord : 0v
Ok will do but I don't have any laptop to open the software (since my laptop is this one and is faulty) I am on my smartphone. Btw I have a ux305UA
Edit : I checked again all the mosfets for continuity (multimeter in ohmmeter mode) and I finally found there is always a pair of pins where I can find...Last edited by Clinteastwood1; 04-03-2021, 04:21 PM.Leave a comment:
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Re: Help me repair this UX305 motherboard please
I get 0V for both when my charger is plugged in...Leave a comment:
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Re: Help me repair this UX305 motherboard please
Mcplslg123 I made the measures for the mosfets I circled in red in my initial post here is what I get on the first pic below.
Sametbey I made the measures in ohms (caliber 200k) in blue on the second pic. Values at 1 mean infinite resistance....Last edited by Clinteastwood1; 04-03-2021, 09:40 AM.Leave a comment:
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Re: Help me repair this UX305 motherboard please
sametbey those schematics are hieroglyphs for me
In fact the ones indicating "1" in diode mode should be in short circuit, because when I use the multimeter in ohmmeter mode it indicates huge resistances for those mosfets (if I understand correctly the "1" in diode mode does not equals to 1 ohm it's a convention to say there is no continuity in the component, meaning huge resistance, at least my multimeter works like that I guess it's a basic one).Last edited by Clinteastwood1; 04-03-2021, 08:38 AM.Leave a comment:
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Re: Help me repair this UX305 motherboard please
Thank you very much guys that's very kind to help me.
I took some mosfets measures before I read your messages, with the multimeter in diode position.
If needed I can take more measures according to your instructions.
The measures indicating "1" mean the mosfet is faulty, right?
Thanks for the doc sametbey, I have an ux305ua it's slightly different from this one, but it could help too...Last edited by Clinteastwood1; 04-03-2021, 06:30 AM.Leave a comment:
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Re: Help me repair this UX305 motherboard please
Hello techtiger and thank you much for your help.
I'd like to test what you suggest but it sounds like chinese to me
I can't locate where are the gate/drain/source on the mosfets since I'm not electronics savvy... But I'm going to search on Google if I can find a tuto for this.
Concerning SN2867RUYR and PR8906 I am afraid I can't find these. Here are pics of the back of my MB:...Leave a comment:
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Re: Help me repair this UX305 motherboard please
Here are the best pics I can take with my phone I hope it helps to identify the mosfets...Leave a comment:
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Re: Help me repair this UX305 motherboard please
At any pin?Leave a comment:
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