How to test an SMD Mosfet 

Hey dude where can i contact you for more knowledge?

Thank you!! I pinned your comment because it gives an indepth understanding of mosfets. I really appreciate the feed back, my knowledge in electronics is large and small in different areas, so I wanted to give my knowledge on what I knew about testing them. Any corrections are appreciated!

@@chasefournier your welcome, no corrections just sharing the tiny bit of knowledge i have on smd mosfets.

@@NewbFixer Thanks for adding this explanation. It really helps those learning (like myself).

@@JacobDubs Your welcome buddy.

This is very helpful!I was wondering what the meaning these dots? everytime i look on mosfets.

Thank you! ☺️☺️

That's fantastic! Glad my video could help you! Also, just to rule out everything, inject voltage and see whats gets hot. It's not super likely that multiple fet's would blow all at the same time, but i suppose there is a possibility.

@@chasefournier Just an update. Tackled the GPU again finally. Originally there was 1 blown mosfet that I butchered and removed. Still would kick the cheap PSU I had for a test bench. Followed your tutorial again, found 7/18 that seemed to be shorted out. Managed to get those off without damaging the board (proud of that), and now my test bench doesn't kill itself. No screen though, but I can't be sure it's the GPU still or the test bench, as the mobo and cpu are also not known to be working or not. But progress I guess? I think the board is toast anyway. After getting all those Mosfets off, I checked the resistance between the little pads left where the pins for the mosfet would be. And they're still reading 1-2 ohms. Sooooo google makes it sound like the copper layer inside the board must have welded itself together. Kinda funny how the one noticeably blown mosfet reads 10k between the pads like the other good ones though. Anyway, thanks again for the video. I had to come back to it again after not trying for a year or so lol.

Thank you! 😊💯

Thank you! 😊💯💯

Thanks man! 💯💯☺️

Appreciate it 😊 I don't think of myself to be an expert in mosfets by any means, but to have the general idea on what to look for using your multimeter I think this is a good resource for repair 😊

Glad to hear! Good luck!

Thank you!!

Thank you!!🙏💯💯

Thank you! :)

Thank you!! 💯☺️☺️

Thank you!!! 🙏🙏🙏💯

No problem man! Glad I could help!!

Thanks @@chasefournier

The gate is always with the source and drain are the 4 pins together in that way I never forget where is the gate and source

Thank you!

Thank you!!

You’re welcome 😊

Thank you!!

ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-rwCiTLvTf6k.html

Usually in the several thousands to millions range. 12v to gnd ohms mode.

No worries! It's basically the same thing, there's the Drain, source and gate on your 3 pin just like the one in this video. But I'd suggest checking the part number whatever mosfet you have and determine if it's a NPN or PNP. And then of course the data sheet to see what pins are which.

King 👑🙏🙏

@@chasefournier No u !

Yes.

Usually due to low resistance to gnd the source to drain will show short but isn't actually shorted. However if you inject voltage at the drain you will know for sure.

Typically with these mosfets the gate will be the single connection by itself.

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In this video, the drain and source are switched (my fault). The source is the 3 connections and it is gnd. The gate shouldn't be low resistance to gnd.

@@chasefournier no probs! But if you ohm read across the source & drain, you should get either extreme high resistance or an open? If you have time, try a sound Church of Christ (not Mormon) thank you. If a mosfet is open (power on) can you jump across the source & drain? Thank you

Drain is the positive side and source is negative. On an Xbox board like in this video, drain and source will show show short, but is low resistance to gnd. In some cases there's a possibility it could be shorted at the drain. Just need to check OHMS and Diode readings

@@chasefournier ok thank you. More for laptop m/b use.

Yes it typically does. Honestly, it depends on the voltage rail. Like if it's a really low voltage rail typically it will have low impedance to ground. So it will show in some cases like 0.5 omhs to ground, and it's not shorted. But like if you have a higher voltage rail like say 3.3v to 12v it should be like 500 ohms to like several thousand. Always test gate against the source to test if the mosfet is bad. But typically, you will see on the drain if that rail is low, it is likely shorted. But because of low impedance sometimes it's not shorted. There's so many variables, you'll have to play it by ear depending on the board you have that your troubleshooting.

@@chasefournier ok so mosfets , coils and i think diodes are reading like 5 or under ohms near the gpu / cpu , thats normal ? Also i have a rog 502 loaptop.. dc jack mosfet had short between source and drain but laptop still turned on , but wouldnt charge.. so guys at badcaps told me to change mosfet so i did.. but no power.. tried 2 mosfets.. Put back old mosfet still no power ... man i think those mosfets burnt something.. are these 2 mosfets the same ? nikos pkch288 uuddpo10c ( replacement ) NIKOS PKCH288 GUD201701 ( original ) ?

@@nayefalkurahi3357 if you have a short on drain, it's likely that that power rail is actually shorted. You will need to refer to my video on voltage injection. basically understanding how to find a shorted component. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-rwCiTLvTf6k.html

Voltage injection will typically show a shorted component. It really depends on the circuit.

You can use a DC power supply, or you can buy a voltage injection tool at northridgefix.com

You got it man!

Drain is 4 pins Source 3 pins Gate 1 pin

@@chasefournier thanks for the quick reply yeah I know that part but I meant on the same part of the board so they shouldn't be touching like you said so I was wondering what if they were solderd to the same part on a board ? Or does that never happened like they never solder gate and source to the same pads cuz that would defeat the whole purpose right

The gate is the control pin to turn the MOSFET on and off. It is always a separate trace.

ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-rwCiTLvTf6k.html

ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-rwCiTLvTf6k.html

Nice

Me too its a FET-ish.