How To Find Short Circuit VRM MosFET With An ESR Meter
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- Опубликовано: 6 июн 2021
- Learn Electronics Repair #062
In this video we look at VRM circuits. These are very common circuits, especially on Motherboards and Graphics Cards. In order to diagnose these devices we need to understand how the VRM works and how to find the faulty component(s) when they fail
This is an important fault finding tutorial - make sure to watch it and if anything is not clear then please post in the comments section below and I will help you because you really need to understand this one
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Thank you
Richard
Great technique. Also, nowaday, you can put thermo camera on it and you will see the heat signature shows up on the shorted phase mosfet.
This man is underrated!
Thanks again for pointing this video to me. I am quite impressed. I have found myself diagnosing this exact fault in vcore a few times, and I will sure find it again eventually, and this approach is going to be really helpful.
Another great video. Cheers!
I stumbled upon this video and have to say, I love your channel! Keep up the good work! I tested this process with my motherboard's VRM that has a shorted high side MOSFET and it indeed worked for isolating which one was bad. In my case, there was also an easier way to tell -- the gate was also shorted to the drain and source. But I'm assuming they don't always fail that way! Very clever idea using an ESR meter. Thanks for sharing.
@doogulass
Sometimes there is a combined driver and dual MOSFET chip driving the inductor coil - in which case you can't access the gate terminals because they are internal inside the chip. Then this method really becomes useful.
This is legendary! I don't have to remove mosfets one by one now!
A legend in my own lunch break eh? Wow!
Comprehensive tutorial, brilliant , I have an asus prime board that is tripping the psu so going to try and fix it.
fascinating insight, thanks for this interesting lesson
Wow, one of the best explanations on RUclips, you sir are a legend. Thank you for sharing
Wow, thanks!
24:27 wow. thank you for that useful tip. I have the same esr meter so I can use your advice.
Good lesson
nice video, very informative.. keep uploading videos
Thanks :-)
very good info :)
Awesome video
Very good, thx.
great content!
Glad you like it!
Nice one, keep it up 👍👍👍
Thanks, I will :-D
I love your stuff and have been watching plenty of them especially your motherboard repair ones. I had a question, at a glance if a motherboard is starting (fans spin) and immediately stopping (fands stop), but removing the 12v CPU power allows it to boot and stay on (no CPU 12v plugged in but fans continually spin, mobo stays "on") what are some things you would check?
In my testing VRMs seem okay (no shorts, similar resistance between same pins on all of them) and vcore on all coil outputs is 0.8v. (ryzen b450). No short from 12v to vcore, and 100 ohms from vcore to ground. I tested a good ryzen (b320) motherboard and it's vcore is also 0.8v. I can seem to figure out what would trigger the motherboard to turn off immediately while CPU 12v in plugged in.
I got both high side short to 12Vin and low side short to ground. MB just turned off mid Win update and goes into hiccup start-stop now. CPU is alive and tested.
Is it safe to assume that VRM mosfet(s) are to be replaced? Should there be any other issue that lead to short or it could just be 'natural' death?
P.S. I am familiar with DC-DC buck theory and prototyping my own convetrers, but have zero experience in PC component level repair.
Ok what about the 5 pound short circuit test u made.on another video
Hi master, merry Christmas, what is the perpose of the vrm coils ?
To lower and regulate the voltage (eg: 12V to 1.xx V).
Where should I look next if the mosfets are not shorted? I know the vcore is the problem since the mobo boots up when cpu cable is unplugged.
Vcore also powers part of the Northbridge so your problem could be there, but there are so many possibilities. In this instance I would suggest you register for free on badcaps forum www.badcaps.net/forum/
The post in the motherboard section (there are separate sections for desktop or laptop) with some pics of your board, the model number etc. Describe what you have tried so far and what happens. I'm sure you will get help there, quite possibly from myself amongst others.
Great work. But as a hobbyist or tinkerer i cant shell out money for all the instruments in market. I have a 2nd gen h61 motherboard that gives the 'beep' in both upper and lower mosfets.
I just ordered a 'short finder' thingy that injects voltage to heat up the shorted component. Wont voltage injection work here?
I've not used one of those 'short finders' you mention. You need to be careful not to inject too high a voltage though, remember there could be low voltage derived rails coming from the one you are injecting voltage in to
@@LearnElectronicsRepair yea true. Injection is sort of the last resort for techs i believe, your method ensures no further damage and is better. 👍
Hi can you put a link pls..i would like to see the item
I absolutely love Dicky Cad
I like your channel but when your explaining your technical skills try to tell where you are putting the probes from the meter ex. Ground to gate I think you what I mean people need to know what you are measuring