How to Check If Your ESC Is Broken (testing your MOSFETS)
How to Check If Your ESC Is Broken: A Comprehensive Guide
Many FPV pilots have encountered a problem with their quadcopter motor/esc (Electronic Speed Controller) but don't know how to check if their ESC is broken. This can be a severe problem, as a broken ESC can cause your quadcopter to malfunction and even catch fire. In this article, we'll show you how to check if your ESC is broken and how you can repair and replace your MOSFETS.
What is a MOSFET?
In simple terms a MOSFET is basically just a switch, in context of an ESC, the job of the MOSFET is to switch the three phases of the brushless motor to make it spin.
Why Do ESCs Break?
All ESC used on drones and quadcopters to drive brushless motors use Metal-Oxide semiconductors (MOSFETs) in the speed controller. MOSFETS are actually one of the most widely produced component on the planet, and almost never fail out of the box. They only fail due to over current, overheating, or over voltage due to a crash/ bad installation or incorrect use outside the operating parameters. Most commonly is during a crash your motor can jam causing a spike in current and voltage that can cause a MOSFET to fail.
How Do I Know If My ESC (MOSFET) is Fried?
1 - Inspect Visually
On some rare occasions a MOSFET may have been placed incorrectly during production and this would mean, and ESC is faulty out of the box, this can be inspected visually (as one of the MOSFET chips will be at a slight angle, or not make the correct contacts.
If you have already used your ESC and on visual inspection you notice one of them seems to be burnt/have some damage then this may be down to user error (such as over current, overheating etc..) Please still get into touch with us so we can see if we can still help, but it is not guaranteed we can issue a replacement under warranty.
2 - Check Continuity on your ESC/MOSFET
If you cannot see any issue visually the next step is to test the MOSFETS themself with a multimeter.
With your ESC unpowered (i.e. no battery connected):
Put your Multimeter into continuity mode
Place one probe on the negative battery terminal/connector, and then check for continuity on each of the motor connectors using the other probe. If you do get continuity make note of what motor this is on, as there is an issue with a MOSFET on this ESC.
Repeat the above but for the positive terminal (one probe on the positive battery terminal/connector), record the location of any continuity beeps
Assuming you had an issue, now we move onto the actual MOSFET for each motor you noticed an issue on. Place one probe on one side of the MOSFET, and move the other probe along the connectors on the other side to check for continuity, if you do get any continuity then mark this MOSFET as faulty.
The video below shows you how to test for this using a multimeter. As a bonus it also shows you how to can repair using a hot air gun.
3 - Check your motor and flight controller
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