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Shortage in 3 terminals of mosfet

maker_iiefijce_1663941788

Sep 23, 2022
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Hi, I have a Bldc motor Controller i dont know what went wrong with the controller, +ive and - ive terminal just shorted. When i opened up the controller all the mosfets in one line shows shortage across all three terminals. What causes all 3 terminals Gate, Drain, Source to shortens itself?
I would also like to simulate this type of shortage on a breadboard if anyone has idea do let me know
 

danadak

Feb 19, 2021
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maker_iiefijce_1663941788

Sep 23, 2022
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Thanks, Dana for your kind reply
I would like to simulate that effect on a breadboard (all gate drain source shortage) can you tell me exactly how can I do that just to have additional knowledge of electronics
 

Alec_t

Jul 7, 2015
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A piece of wire will simulate a short circuit, but I don't see how that will add to your knowledge?
 

maker_iiefijce_1663941788

Sep 23, 2022
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A piece of wire will temporarily shorts the terminals but when I remove that wire shortage will be gone
What I want to simulate is how MOSFETs could be permanently damaged i.e. Showing shortage on all three terminals
 

Alec_t

Jul 7, 2015
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Use three pieces of wire (G to S, G to D, D to S), and don't remove them.
If you want to simulate the fault actually occurring, a timed switch across the relevant terminals could be used. Again, that won't add much to your knowledge. You need to identify which of the many causes of FET failure is possible in your particular controller circuit.
 

maker_iiefijce_1663941788

Sep 23, 2022
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Alec try to understand what I'm trying to achieve
I want to damage my spare Mosfet (take IRF740 as example) to permanently in such a way all three terminals are shorted by itself (not by some kind of wire)
If I know practically what is done it would be a bonus in my knowledge
 

danadak

Feb 19, 2021
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Knowledge gained would be to examine the internal damage as the pics
show. Plus there are variants to these failures, all the way to package blowup.
But knowing the 3 pins are shorted, by any means, is limiting in gaining any
specific additional knowledge.....

Can you describe what your thinking is here as its not clear to me what
you can gain here. Note a way of looking at cause and effect is to use a DSO
and set it up for V and T triggers, and data logging, to see what V or I went
out of spec as it took out the MOSFET. Single shot time base setting.

And use a DSO to look at recurring transients that will eventually blow part but
occur with some frequency before device destruction. Using masks or just more
trigger settings for excessive parameters.

Regards,Dana.
 

John Canon

Jun 1, 2022
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Alec try to understand what I'm trying to achieve
I want to damage my spare Mosfet (take IRF740 as example) to permanently in such a way all three terminals are shorted by itself (not by some kind of wire)
If I know practically what is done it would be a bonus in my knowledge
Mosfets hate reverse voltage. You could install a DPDT reversing switch like I saw on one of the other threads.
Mosfet ByeBye.jpg
 

hevans1944

Hop - AC8NS
Jun 21, 2012
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Hi, I have a Bldc motor Controller i dont know what went wrong with the controller, +ive and - ive terminal just shorted. When i opened up the controller all the mosfets in one line shows shortage across all three terminals. What causes all 3 terminals Gate, Drain, Source to shortens itself?
I would also like to simulate this type of shortage on a breadboard if anyone has idea do let me know
The most likely cause is too much current in the mosfets, which will melt the silicon die inside the package and short everything inside together. Why would you want to simulate this effect on a breadboard? Destroying components tells you nothing, other than you have successfully destroyed the component. You will learn nothing from the experience that you don't already know: if all three terminals of a mosfet are internally shorted together, the mosfet does not work.

The REAL problem is discovering WHY your mosfets all shorted. No amount of "simulation" will ever reveal "why" or "how" failure occurred. You need real-world observation and test of actual circuits with electronic instruments, plus troubleshooting skills, not computer simulations. Or just go ahead and buy another BLDC motor controller/power supply and move on with your life. Maybe the one that failed was an imported piece of junk. There is a lot of that kind of stuff floating around for unsuspecting buyers.
 
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