Asus Strix RX 570 8GB Repair, mosfet Help

Joined
Nov 4, 2010
Messages
24
im trying to repair an asus srtix rx 570, i found a short on 12v line it was a bad mosfet
i cant find any data sheet about the QN3014 mosfet that it uses, and i cant find anywhere that sells it
can anyone help me with an alternative mosfet that i can use, as i dont know that much about mosfets
im just trying to repair things as a hobby and i have only fixed a few graphics cards so far




 
im trying to repair an asus srtix rx 570, i found a short on 12v line it was a bad mosfet
i cant find any data sheet about the QN3014 mosfet that it uses, and i cant find anywhere that sells it
can anyone help me with an alternative mosfet that i can use, as i dont know that much about mosfets
im just trying to repair things as a hobby and i have only fixed a few graphics cards so far




A high res close-up of the chip would help.
They don't always put the full part number on the chip. Likely any 3014 MOSFET would work provided it's in the correct package.

Or you are reading the board labels and your looking at q(transistor) n(npn type)3014, which doesn't tell you anything
 
A high res close-up of the chip would help.
They don't always put the full part number on the chip. Likely any 3014 MOSFET would work provided it's in the correct package.

Or you are reading the board labels and your looking at q(transistor) n(npn type)3014, which doesn't tell you anything

WIN_20211219_13_43_30_Pro.jpg
 
Yeah, coming up blank. Are you sure thats a mosfet? The only thing i found with a similar number was a gate driver, but it may not be available in that package. How about a photo of the entire board, with an arrow pointing at the chip? RazorWind is the resident "fixer of GPU's for personal enjoyment" here.

An image of the chip and area around it, still close up, but not quite electron microscope style might be helpful as well.
 
That logo is for Ubiq Semincondutor (apparently now part of uPI). I was able to find datasheets for the QN3103 and QN3105, which appear to be similar, but not the 3104. Not the first time I've come up empty when looking for a Ubiq part - I think they may reserve some part numbers for proprietary applications, and they don't seem to let their parts get into retail channels very much, either.

It appears that the 3105 is a little bit better, and may have just superseded the 3104. Lacking any better options, you could probably use a QN3105 and it would work OK, assuming that one failed FET is the only problem.

Datasheet for the QN3105.
https://www.ubiq-semi.com/files/2397/2da00fe8-9368-11ea-8d8d-d411d603879c

Edit: I found a few QN3105s on ebay that, at least appear to be real in the photo.
 
  • Like
Reactions: travm
like this
That is a pretty epic logo. I think they were going for a ying/yang thing but it looks more like something else.
 
could i use the mosfet thats on the asus rx570 expedition? i repaired one and have a few mosfets left
its a 4c09b mosfet https://datasheetgo.com/4c09b-datasheet-mosfet/
Probably, but it may run a little hot. You may notice that the RDSon is quite a bit higher than the Ubiq 3105. That means it will dissipate more energy as heat, which you then have to cool. I suspect it would work, though.

Also, and I can say this from experience, when soldering these big SMD power FETs, it pay to preheat the board first, and then be as quick as possible with the hot air when you install the new ones. It's real easy to damage them when you only use the hot air gun.
 
Probably, but it may run a little hot. You may notice that the RDSon is quite a bit higher than the Ubiq 3105. That means it will dissipate more energy as heat, which you then have to cool. I suspect it would work, though.

Also, and I can say this from experience, when soldering these big SMD power FETs, it pay to preheat the board first, and then be as quick as possible with the hot air when you install the new ones. It's real easy to damage them when you only use the hot air gun.
thx 4 the reply
yeah the vrm on the expedition runs very hot, was just checking it would be ok to use them just to test if the card works till i can get some QN3105s
i cant preheat a board that big, but there are no components on the back of the board where the mosfets are so i will heat it underneath for a while its all i can do
 
Last edited:
Back
Top