This is the clearest and best demonstration of checking Mosfets I've found so far. Good on you for taking the time and trouble to do this for mugs like me! My search is over, I'm now confident in doing this.
this video is 6 years old as i watched it today, even six years after posting it it still helping people. thats brilliant, thank you i am more wiser on testing mosfet now.
I had a trailer brake controller which was constantly applying the trailer brakes even when the truck was off. Happened to find this video while googling the transistor number and found the transistor was shorted internally just like the one in this video. Thank you so much!!!
Oddly enough, I have a B&K component tester that shows 2.9vdc output on the diode setting but will NOT charge an IRF520. I have a Fluke digital multimeter that outputs only 2.5vdc on the diode setting but works perfectly on the SAME IRF520 every time.
An easy tester is a 9v battery with a single diode and led(with resistor if you want it, for indication) on one probe. Subtract the diode and led voltage and you got a simple polarity tester. (You still need a meter to measure voltage drop on it but got more than 2/3 volts to play with)😊
Thanks for showing how to do this with a known good mosfet and a bad one..no more being confused by the other videos on how to test!! You won yourself a subscriber!!
Thx a lot for your movie! Today I bought a simple china component tester! It make my live so easier! I don‘t soldering anything out and nothing! Clip on the wire measure in secounds, done! Perfect! 💪💪💪
Both of my meters are similar types (read the same way) as yours. Other videos show different readouts, and I was still confused. Now with yours, I know my MOSFET IS faulty. Thank you.
Many thanks for this tutorial. Just got some Mosfets off a Brushless motor ESC and found 2 duff and 4 working OK. I'm making a flashing 10W LED lamp to put in my model aircraft for when they go in to cloud or otherwise out of sight, and needed the mosfets to switch the power on and off to the LED driver.
simple and right to the point " that was a good way to demonstrate that ! Also if checking power mosfets with ohm meter set to ohms reading and you get ANY reading between any combination of gate to drain or source to gate ect that shows a dead short the mosfet is bad it's shorted ! but make sure to discharge it by holding the three leads between your finger and thumb before doing dead short test this way ! I have had many mosfets read .437 and ( point 437) work fine as that is residual capacitance in the internal circuit ! always check a new one before installing it !
Thanks for this tutorial. It helped me fix a GPS problem (level shifter MOSFET was being uncooperative) with my HAB flight tracker for my dissertation.
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Be aware that this works *only if* the voltage provided by the dmm to charge the gate is above the mosfet's gate threshold voltage. The high-voltage fets have Vgs-thr above 4V. Some even atound 10V. The low-signal and ultra-low voltage have lower voltages but not much below 4V. A regular dmm outputs about 1V...2V with high impedance. Some up to 8V on a 10Mohm load. It is safer to use a variable power supply with a high-value series resistor as s gate charger.
Thanks for the help! Because of this video I found that a MOSFET I suspected to be bad turned out to be good. Ended up fixing a device which really had a bad electrolytic cap. Who would have guessed?
awesome video.. the most simple and easy explanation on the internet.. everyone else seems to make it so difficult.. good job.. if u can show this on a laptop motherboard that would be very helpful .. thanks
I found this video informative and great to have produced. I forgot the charge up of source to drain part to develop a capacitive voltage for a short while in good MOSFETs. I would want to double check my schematics of the MOSFET to know where the source and drain are vs gate to drain shorts. I don't have a transistor checker multimeter yet.
Great Info, Thank you! But for the sake of newbies like me, you should have explained as well how come touching the Red Probe of the meter (with the meter in Diode Test Mode) to the MOSFET Gate charges it (if you get my drift, that is). Thanks again.
build a simple tester with an old analog meter, or even a vu meter movement. use a 9 v bat. or two in series with a resister (to limit current to full scale deflection) and red and black alligator clips. clip across collector-emitter and activate base with just a finger from base to col. Same with MOSFETs. you can actually see the transistor switch off or on with a slight brush against the gate from either drain or source. sorry, cannot easily do a video of this but a very simple analog "super ohmmeter" demonstrates transistor,fet action. Also handy to confirm leakage of capacitors that digital meters miss.
Thankyou for the tutorial. I have a Technic amplifer with an issue with high voltage. I think the Toshiba SK117 could be defective, the gate with the old part appears to be the center pin. I am getting low values on the Diode test 145 etc ( my meter is 3 diget), so i assume all must be defective. As i get no 1 (which is OL) on your meter
Awesome video. I have a bad power board in my LG oled tv and I suspect one or two mosfets are burnt. Gonna use your method to test those. Thanks a bunch.
So, that mosfet that you are checking is a P-channel type because the Gate is at the positive probe?Am I correct? And how to determine of what pin is the Base, Drain, and Source by using only multimeter (diode mode) amd without looking the specification of that mosfet parts?
Thanks good info to know. I'm trying to learn how to use components like these for fun and so maybe I can better understand them so I can repair damaged electronics to save me a little cash. Mostly because it's fun tho lol.
Does this work for a NTE291 transistor? I just bought a new NTE291 and wanted to test it before I install in, but it doesn't quite test like this. Is the NTE291 different than this? I've watched a few videos how to test transistors and my new NTE291 doesn't do the same as the test videos so I'm confused. I hope I didn't buy a bad "new" transistor.
I can't seem to get my fet to turn on .. it does have a 20-30v VGS rating though .. I'm assuming that's why, right ? Thanks for the video ! Very nice and clear !
The real advantage of mosfets over traditional old fashioned BPJT, is that they are more efficient. The voltage drop over a BPJT is about 0.5-0.7 volts. The voltage drop over MOSFET is 0.1-0.2 volts. Calculated out of Rds(on) x current Ampers. You lose much less power, to heat. Though BPJT switch faster. Just personal experience, I am not an expert.
Hi, there are noises coming from my left speaker only, and right speakers are functioning good perfectly, what could be the problem here? The noises are like interference.
In my testing/checking MOSFETs using Multi-meter, when the gate is charged, why some MOSFETs (N-channel & P-channel), the drain to source let us say 0.002 or less my meter reads, others starts with more higher like 0.435 and running up as fast as a second or half a second until showing infinite? Discharged test is working (no reading on drain to source). What does it mean? Does all MOSFETs behave like that?
Thank You Good tutorial..
+Tuan Sathiyan You're welcome. Thanks for the nice comment! Please like and subscribe!
+Runforlife ,,,very clear explanation ,,,good channel!
thanks
Thanks!
This is the clearest and best demonstration of checking Mosfets I've found so far. Good on you for taking the time and trouble to do this for mugs like me! My search is over, I'm now confident in doing this.
it was so annoying with all the other videos until I found this
I got myself a transistor tester, but this method is still extremely valuable when you don't have access to other tools. Thank you.
this video is 6 years old as i watched it today, even six years after posting it it still helping people.
thats brilliant, thank you i am more wiser on testing mosfet now.
I had a trailer brake controller which was constantly applying the trailer brakes even when the truck was off. Happened to find this video while googling the transistor number and found the transistor was shorted internally just like the one in this video. Thank you so much!!!
Nice video! Just a notice: most multimeter operates between 1V to 2V in diode tester mode which is not enough for a switching MOSFET to open.
Thanks for the info.
I saw a lot of videos and was wondering, Why my DMM can't charge Capacitor by touching the Gate.
Oddly enough, I have a B&K component tester that shows 2.9vdc output on the diode setting but will NOT charge an IRF520. I have a Fluke digital multimeter that outputs only 2.5vdc on the diode setting but works perfectly on the SAME IRF520 every time.
yeah some meters test with 7 Volt and some 3.5 V or lower etc, this needs to be checked first with another multimeter.
An easy tester is a 9v battery with a single diode and led(with resistor if you want it, for indication) on one probe. Subtract the diode and led voltage and you got a simple polarity tester. (You still need a meter to measure voltage drop on it but got more than 2/3 volts to play with)😊
Watched the video, immediately tested my MOSFET. Thank you SO much for the information!
Thanks for showing how to do this with a known good mosfet and a bad one..no more being confused by the other videos on how to test!! You won yourself a subscriber!!
perfect video, clear English & easy to comprehend
That's worth a subscribe. So many videos, so technical from so many super smart dudes that could not correlate to me so easily as you have done ty
Masha-Allah. Zazakallah Khyer. You are very helpful for every engineering students.May you live a long life with Full of gladness and health.
Thx a lot for your movie! Today I bought a simple china component tester! It make my live so easier! I don‘t soldering anything out and nothing! Clip on the wire measure in secounds, done! Perfect! 💪💪💪
Thank you for sharing. Good explanatory and simple tools to test. Thank you again.
Thanks a lot for teaching me how to test a mosfet hope i good learning more from you like other type of mosfet how to test thank you very much !
Both of my meters are similar types (read the same way) as yours. Other videos show different readouts, and I was still confused. Now with yours, I know my MOSFET IS faulty. Thank you.
Excellent video mate, first class! You really do make it simple even for newbie's like me to understand and for that I thank you very much.👍
Many thanks for this tutorial. Just got some Mosfets off a Brushless motor ESC and found 2 duff and 4 working OK. I'm making a flashing 10W LED lamp to put in my model aircraft for when they go in to cloud or otherwise out of sight, and needed the mosfets to switch the power on and off to the LED driver.
Short and to the point, thank you!
Man, I would just like to express my sincere thank you!
A video well done. I design circuits, but did not have this test technique in my bag of tricks. Thank you.
+TheBdd4 Thanks for your comment! :)
simple and right to the point " that was a good way to demonstrate that ! Also if checking power mosfets with ohm meter set to ohms reading and you get ANY reading between any combination of gate to drain or source to gate ect that shows a dead short the mosfet is bad it's shorted ! but make sure to discharge it by holding the three leads between your finger and thumb before doing dead short test this way ! I have had many mosfets read .437 and ( point 437) work fine as that is residual capacitance in the internal circuit ! always check a new one before installing it !
Thanks for this tutorial. It helped me fix a GPS problem (level shifter MOSFET was being uncooperative) with my HAB flight tracker for my dissertation.
Be aware that this works *only if* the voltage provided by the dmm to charge the gate is above the mosfet's gate threshold voltage.
The high-voltage fets have Vgs-thr above 4V. Some even atound 10V.
The low-signal and ultra-low voltage have lower voltages but not much below 4V.
A regular dmm outputs about 1V...2V with high impedance. Some up to 8V on a 10Mohm load.
It is safer to use a variable power supply with a high-value series resistor as s gate charger.
Thanks for the help! Because of this video I found that a MOSFET I suspected to be bad turned out to be good. Ended up fixing a device which really had a bad electrolytic cap. Who would have guessed?
Thanks, it's clear. But what about P-channel MOSFET? Is it the same way to test?
My question too 😁 do the test on P-channel! 👍
THANK YOU. helped me figure out for the first time of my life if a mosfet it good or not! :D
Does the measurements make any difference when its mounted on the PCB ?
This is a great tutorial, I have just tried this with my IRFZ44N Mosfet and it works perfect. I have liked and subscribed. Thank John.... :)
Great. Thanks for sharing!
Thanks, helped me test and prove a MOSFET in a Honda CBR indicator relay was good
Awesome video for learning, also your way of explaining is well. Thanks brother-Pakistan
good tutorial.at the beginning you have to short those pins with the negative lead but everything is correct.once again good job.
awesome video.. the most simple and easy explanation on the internet.. everyone else seems to make it so difficult.. good job.. if u can show this on a laptop motherboard that would be very helpful .. thanks
THANK YOU ! you saved me a ton of trouble shooting !
On and Off state ...again learned something new... thx verry much.
I found this video informative and great to have produced. I forgot the charge up of source to drain part to develop a capacitive voltage for a short while in good MOSFETs. I would want to double check my schematics of the MOSFET to know where the source and drain are vs gate to drain shorts. I don't have a transistor checker multimeter yet.
Very simple and valuable explanation. Useful for beginners like me. Like to watch your other videos. Tanks.
This video is actually really good
Fantastic and educative video ❤❤❤❤🎉 excellent work bros.
This works because the mosfet is of a n-channel type. On a p-channel you have to switch your polarity of the multi meter.
very clear explanation. now I know. Keep it up. Thanx u.
This is how you should do a tutorial short and to the point!
Great Info, Thank you! But for the sake of newbies like me, you should have explained as well how come touching the Red Probe of the meter (with the meter in Diode Test Mode) to the MOSFET Gate charges it (if you get my drift, that is). Thanks again.
Saved me a ton of time. Thank you!!!
Hi, is this method for all types of transistors? Or just mosffets. And does it matter if its PNP or NPN? Thanks
tnx so much for sharing ung knowledge👍👍👍GODBLESS
Outstanding video. Very well explain and simple to understand! Keep it coming... 73, Joe-K4JGA - JGA Electronics Repair Center, Florida
Good tutorial
build a simple tester with an old analog meter, or even a vu meter movement. use a 9 v bat. or two in series with a resister (to limit current to full scale deflection) and red and black alligator clips. clip across collector-emitter and activate base with just a finger from base to col. Same with MOSFETs. you can actually see the transistor switch off or on with a slight brush against the gate from either drain or source. sorry, cannot easily do a video of this but a very simple analog "super ohmmeter" demonstrates transistor,fet action. Also handy to confirm leakage of capacitors that digital meters miss.
Very nice awesome video. Thanks sir (Pakistan)
It's correct method,I do the same👍
very nice, very clar, thanks
Excellent demo. Thank you.
Perfect and practical bro 👌
Thankyou for the tutorial. I have a Technic amplifer with an issue with high voltage. I think the Toshiba SK117 could be defective, the gate with the old part appears to be the center pin. I am getting low values on the Diode test 145 etc ( my meter is 3 diget), so i assume all must be defective. As i get no 1 (which is OL) on your meter
What's missing in this tutorial is identifying first the Mosfet name, it's 2sk3911.
Excellent tutorial explained perfectly, thank you.
Thank u for ur lessons it help me alot great work explain very clearly an simple
Awesome video. I have a bad power board in my LG oled tv and I suspect one or two mosfets are burnt. Gonna use your method to test those. Thanks a bunch.
Thanks dude. Very well explained without wasting any time. Is this test work on both N-channel & P-channel MOSFET???
Jameeluddin Sheikh n-channel needs a positive voltage on gate to switch on, p-channel needs negative. So I guess you just reverse the test leads.
This is how i've tested mosfets in the past. I found using the meter to charge the gate didn't work with every meter i tried.
this is the tuturial i like ...1m likes for u...
Nice explained 👌
So, that mosfet that you are checking is a P-channel type because the Gate is at the positive probe?Am I correct? And how to determine of what pin is the Base, Drain, and Source by using only multimeter (diode mode) amd without looking the specification of that mosfet parts?
Thank u for your good Training
Good, i hve been looking for something like this thank you for sharing
Thanks good info to know. I'm trying to learn how to use components like these for fun and so maybe I can better understand them so I can repair damaged electronics to save me a little cash. Mostly because it's fun tho lol.
Nice tutorial! Should I remove the mosfet before testing? or can I test it while in the PCB? Thank you!
Sancho Cabatay u should remove
Does this work for a NTE291 transistor? I just bought a new NTE291 and wanted to test it before I install in, but it doesn't quite test like this. Is the NTE291 different than this? I've watched a few videos how to test transistors and my new NTE291 doesn't do the same as the test videos so I'm confused. I hope I didn't buy a bad "new" transistor.
Can the same test be done while the transistor is soldered in the machine? Or do you need to remove the part first?
That was good. Thanks. A bit missing show parasite mosfet diode.
thank you............. goods information
Good one. I like your explanation. Thanks for this vid.
Great video thanks a lot
I can't seem to get my fet to turn on .. it does have a 20-30v VGS rating though .. I'm assuming that's why, right ?
Thanks for the video ! Very nice and clear !
Yes, the meter is not putting enough voltage on the gate to turn it on. Try using three 9v batteries in series, or a power supply.
Hello,
Thank you very much for this info/tutorial. ☺
This is what i needed thanks
Very informational video, thank you very much for posting :)
Will this test work if the MOSFET is still soldered to the board?
Really informative enjoyed it
The real advantage of mosfets over traditional old fashioned BPJT, is that they are more efficient.
The voltage drop over a BPJT is about 0.5-0.7 volts.
The voltage drop over MOSFET is 0.1-0.2 volts. Calculated out of Rds(on) x current Ampers.
You lose much less power, to heat.
Though BPJT switch faster.
Just personal experience, I am not an expert.
Very useful. Thank you.
Nice video, thanks.
What we want starts at 0:44.
thank you so much for such great explanation.
Thank you!
Great tips thank you so much 😊 😊
yes good tutorial..could of thrown out a lot of good ones if i never would of seen this video..thank you
Is the mosfet also broken if I can't get any connection while doing everything you did? Or am I probably doing something wrong?
Witch company and model of multimeter used in this tutorial..plsss share the info multimeter....
Good video.How do you know that the first one is the gate,drain and last is source?
Thank you so much, i have learnt something today.
Thank you
How do you test them when they are still in the circuit board? Do you have to remove them to test properly?
Thank you for your video
HI. well explained. in very simple way. thank you very much
That is: "shorted", not "shorten". Thanks for the video, very useful and informative.
Hi, there are noises coming from my left speaker only, and right speakers are functioning good perfectly, what could be the problem here? The noises are like interference.
nice tutorial
Thanks for this great tutorial.
You are the best bro
In my testing/checking MOSFETs using Multi-meter, when the gate is charged, why some MOSFETs (N-channel & P-channel), the drain to source let us say 0.002 or less my meter reads, others starts with more higher like 0.435 and running up as fast as a second or half a second until showing infinite? Discharged test is working (no reading on drain to source). What does it mean? Does all MOSFETs behave like that?
Thanks awesome explanation