Help with component on a  NVIDIA GTX 1080 ti - Page 1
Forum section: electronics / repair

author: 4cx10000
author_rank: Regular Contributor
timestamp: December 04, 2018, 05:11:22 pm
content: Hi!A friend of mine brought in a dead NVIDIA GTX 1080 ti that, as he claim, left a small amount of smoke when he connected the 6- and 8-pin PCI Express power plugs from the power supply. Took the board under my microscope and discovered, as you can see in the picture, a burned 8-pin component which seems to be a mosfet. Pin 1-3 and 5-8 is connected together, pin 4 probably the gate. Anyone know where I can find one? Have vacuum cleaned internet but to no avail; nothing more than dust found.Thanks in advance

author: wraper
author_rank: Unknown
timestamp: December 04, 2018, 05:20:13 pm
content: It's EMB20P03V. Order from China or search for similar.http://www.excelliancemos.com/download_prod_s.php?ds=246&file=2

author: 4cx10000
author_rank: Regular Contributor
timestamp: December 04, 2018, 05:34:47 pm
content: Thanks you so much Wraper for quick reply!Seems that my search did not contain the right characters!Non of the usual distributors seems to have it, so I will follow your advice.Thanks again!

author: Rasz
author_rank: Super Contributor
timestamp: December 04, 2018, 07:04:56 pm
content: are those on upper or lower side? did shorting put 12V into gpu?

author: 4cx10000
author_rank: Regular Contributor
timestamp: December 04, 2018, 07:57:22 pm
content: Hi Rasz!I do not know, but the two mosfet's in the picture is on the lower side of the board. There is an IC, two SOT23 transistors close to the mosfet's and on the upper side, above these components, there is an inductor and a couple of electrolytics, but I did not have time to figure out any more, but as I wrote, I will do that tomorrow.

author: perieanuo
author_rank: Frequent Contributor
timestamp: December 05, 2018, 08:53:57 am
content: any equivalent mosfet found on spare board will do better than china ebay mosfetEnvoyé de mon HUAWEI NXT-L29 en utilisant Tapatalk

author: 4cx10000
author_rank: Regular Contributor
timestamp: December 05, 2018, 09:28:13 am
content: perieanuoWell, then I will have to find one and the truth is that I have not many graphic cards lying around, but thanks for the advice.I may look up an equivalent instead of order them from China, but saw that the mosfet from same manufacturer, as the ones on the board, can be ordered, so I will probably do so.

author: perieanuo
author_rank: Frequent Contributor
timestamp: December 05, 2018, 09:53:22 am
content: and someone already sad this, usually the mosfets die in pair, chack all mosfets from short, inductances for continuity, check all voltages (capacitors) not to be shorted also.most of the time replacing 1-2 mosfets is the trickregards,pierre

author: 4cx10000
author_rank: Regular Contributor
timestamp: December 05, 2018, 10:38:25 am
content: Thanks perieanuo!Yes, both are gone and even if any of them weren't, I would certainly replace them anyway. Hopefully replacing both mosfets will do trick, but as Murphy sometimes gets his hands on my boards, something else might have passed away...

author: perieanuo
author_rank: Frequent Contributor
timestamp: December 05, 2018, 11:00:26 am
content: Quote from: 4cx10000 on December 05, 2018, 10:38:25 amI repaired almost 2 years some mobo-s in a shop, usually it's just that in 95% of the time, sometimes control IC for some voltage synthese dies.easy to replace with hotair, just have to have some spares arround.sometimes also I had found shorted capacitors after I detected burned mosfets (well my method was to see what voltage was involved then apply that voltage with high current capable psu and increasing current limit until I found the hot component (literally hot).I know it's a little bit odd but it works if you have big volumes and you're on tight time scheduleInvestigate the causes is overcomplicated, put the scope, make the dut on high load, check spikes...Just changing the defective mosfets/caps do the trick in almost all casesregards,pierre

author: SparkyFX
author_rank: Frequent Contributor
timestamp: December 05, 2018, 11:37:04 am
content: Don´t forget to dry the board before doing hot air rework ... just mentioning.Inserting the additional PCI Express connectors to the graphics card while hot was obviously a bad idea, as they do not have something like a ground-first connection guarantee (e.g. longer pins for ground). Wiggling while insertion might connect a low impedance supply relative to a ground connection with a lot less current carrying capacity than intended. I reckon the resulting voltage drop shifted these FETs outside their operational range.Long story short: i hope the ground plane connection on his motherboard is still OK as well.

author: wraper
author_rank: Unknown
timestamp: December 05, 2018, 11:55:17 am
content: Quote from: SparkyFX on December 05, 2018, 11:37:04 amPopcorning while replacing such small mosfet is nearly impossible. Replacing GPU would be another thing.

author: SparkyFX
author_rank: Frequent Contributor
timestamp: December 05, 2018, 10:29:24 pm
content: I thought the popcorning is about the water content of the PCB layers (small amounts of water aquired hygroscopically), not mainly the components package (also aquires water).

author: wraper
author_rank: Unknown
timestamp: December 05, 2018, 10:38:16 pm
content: Quote from: SparkyFX on December 05, 2018, 10:29:24 pmI'm talking about PCB. MOSFETs won't popcorn even you try to do so. Unless it's some very moisture sensitive one stored in humid environment. FR4 won't popcorn as well, unless you extremely overheat it or heat very large area like when replacing GPU. And even then popcorning would happen only on some very sensitive boards. Generally baking is not practical. GPU itself is completely different thing, though.

author: lordvader88
author_rank: Frequent Contributor
timestamp: December 07, 2018, 04:49:33 am
content: Quote from: perieanuo on December 05, 2018, 08:53:57 amBroken GPUs sell for a lot of cash, sadly, as someone that would like to fix them for funWhat I what to know is which spec's really should be similar, and which don't matter. And what if u use a way better MOSFET ?? IDK if that would really work either, since all the feedback and monitoring networks might get thrown way off. Changing that stuff would be way harder than just swapping a single fetIDK very much about mosfet spec's past current/voltage rating, Rds drain-source resistance. Their frequency response and on/off times must be critical at the speeds they work at in high end stuff like 1080 ti, over 1 MHz, at least collectively across the phases, on some of the top GPU and mobo's

author: wraper
author_rank: Unknown
timestamp: December 07, 2018, 05:17:22 am
content: Quote from: perieanuo on December 05, 2018, 08:53:57 amHow it would do better than original part? If you want to use equivalent, then buy from Mouser, Digikey, element14...

author: Rasz
author_rank: Super Contributor
timestamp: December 07, 2018, 05:04:33 pm
content: Quote from: lordvader88 on December 07, 2018, 04:49:33 amits a $600-1000 card, you replace withsameparts from reputable distributor