How to use a digital multimeter to measure whether the heating tube is damaged?
Calculate the resistance value of the heating tube according to the parameters, and then measure it with the resistance file of the multimeter according to the resistance value. The resistance is generally divided into cold and hot states. The multiple of the difference is 10 times larger depending on the material, so the test is not one The constant standard, as long as it is not 0 (short-circuit the test leads first, look at the displayed data, and measure the resistance value of the heating tube after subtracting the data at the time of the short-circuit), or the resistance value is greater than 100 ohms, then it can indicate the heating tube It is good, otherwise it is damaged.
Digital multimeter to measure AC voltage: connect the black test lead to the ground (marked in the test lead socket), and the red pen to the AC (or V letter plus one) hole, the gear point to AC~ column 750 (some is 1000) ( If measuring 220V) range. Then the two pens touch the two holes of the power socket respectively, and the reading is the AC voltage value.
Digital multimeter to measure DC voltage: measure AC at the same time, but the red pen is connected to the + hole, and the red pen is also in contact with the power supply + pole. The gear is at DC (or there is a short horizontal line under the letter V). small. For example, when testing a AA battery, select the 2V range. If the polarity is reversed, there will be a negative display before the reading.