How to use a multimeter to check whether the ESC is short-circuited?

After building your FPV drone, the first power-on test is called the Smoke Test. It refers to directly powering on the device after repairing or changing a piece of hardware or a hardware group. If there is no smoke the device passes the test. A multimeter is a very commonly used and practical tool in circuit testing and repair. Generally, when we DIY our FPV drone, we will use a multimeter to check whether our electronic products - flight control and ESC are short-circuited to avoid smoke when powered on.

So how to use a multimeter to detect it?

1. First we need to disconnect the power supply of the FPV drone and plug in the test leads of the multimeter. The pens are divided into two parts: red and black. Plug the black test lead into the COM port on the multimeter, plug the red test lead into the voltage resistor port next to it, and adjust the multimeter to the buzzer position (the icon on the dial looks a bit like a wifi icon). The red one is the positive electrode and the black one is the negative electrode. When the two test pens touch each other, you can hear a buzzing sound, thus confirming that the multimeter is in normal working condition. First check the ESC power supply part. The red detection pen first touches the positive pole of the ESC power supply, and the black detection pen touches the negative pole.
2. Please note, you may hear a buzzing sound during the first test, but it does not mean that there is a short circuit, because there is a capacitor connected in parallel to the middle of the power supply, and the capacitor may be charged. Then the capacitor discharges when the detection pen comes into contact, causing the multimeter to mistakenly believe that there is a short circuit. It is recommended to try the test several times. In most cases, there will be no beeping sound the second time, which means that our power cord is welded normally.
3. Then we can check whether there is a short circuit in the motor pad part of the ESC. Keep the red detection pen in contact with the positive electrode of the ESC, and check the motor pads one by one with the black detection pen. If a buzzing sound is heard from any path, it means there is a short circuit. If there is no buzzing sound, it means it is normal. After that, we put down the red detection pen and replaced it with a black detection pen to touch the negative electrode of the ESC power supply. Then recheck the motor pads one by one to make the results more accurate. If you don’t hear a beep after two tests, it means your ESC is normal.

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