The AMS1117 series regulators are available in an adjustable version and a variety of fixed voltage versions. They are designed to provide 1A output current and the operating voltage difference can be as low as 1V. At the maximum output current, the minimum voltage difference of the AMS1117 device is guaranteed not to exceed 1.3V, and it will gradually decrease as the load current decreases.

It depends on how you test it! The voltage between the output and GND can be measured when the power is on. As mentioned above, if the input is 5V and the deviation between the output and 3.3 is too large, it is basically less. When the power is off, you can also test whether the input and output are short-circuited to ground, or you can do it Certain judgment, in addition, it can also be used after removal

Use the ‘diode’ gear of the multimeter regardless of the ‘pole’, and any short circuit between the three legs (buzzer sound) is breakdown-bad, not sound-good

If it is not powered on, check if there is a short circuit between the input, output and GND. If there is a short circuit, there is no need to test it again, it must be broken.

If there is no short circuit, power on and test again.

It is best to disconnect other circuits to prevent damage to the lower 3.3V

The test can test whether the 3.3V voltage is correct, and whether the load capacity works

In addition, what you need to know is that pin 1 of 1117 is grounding, pin 2 is output, and pin 3 is input. Check if the hand is hot. If the 1117 is very hot, it may not mean that the 1117 is broken. It is very likely that the load on the back of the 1117 is too heavy or short-circuited. It is recommended to measure the electrolytic capacitors around 1117 to see if there is a short circuit. The 1117 is generally used as a 3-terminal regulator chip. It is impossible to measure directly with a multimeter. It is recommended to solder it with an air gun or a soldering iron. According to the chip data sheet, ground pin 1 of 1117, and add +5V DC power to pin 3 to see pin 1 and pin 2 (the middle pin is usually the same as the upper pin). (The heat sink is connected) Whether there is a voltage output of about 3.3V, to judge the quality of the 1117.