Which multimeter is best for professional electricians to use?
The measurement error of the pointer multimeter is large and the conversion rate is slow, but the display of measuring the charge and discharge of the capacitor is intuitive. The AC voltage block uses half-wave rectification (diode rectification). Therefore, the measurement error of the AC voltage block of the pointer multimeter is large because the AC voltage block uses half-wave rectification, so it is said The AC voltage block of the pointer multimeter measures the average value of the alternating current because the measured AC signal is divided by the voltage divider resistor and then rectified by half-wave rectification. The rectified DC current reflects the average value of the alternating current. The input impedance of the pointer multimeter is not that of the digital multimeter. The input impedance is high, and the sensitivity is not as high as that of a digital multimeter. However, professional electricians still recommend the MF-47 pointer multimeter. The new MF-47 circuit design has varistor overvoltage protection components installed on the electrical barrier and current barrier respectively. Some MF -47. MF-47 is not suitable for measuring AC power for a long time. It is prone to burning the voltage dividing resistor at the lowest level of the AC voltage block and the rectifier diode in the rectifier, causing a large measurement error in the AC voltage block or failure of all AC voltage levels. ( If the lowest-grade voltage-dividing resistor among the series-connected voltage-dividing resistors in the AC voltage block is burned out, that is, the 38.3K resistor connected to the AC 10V stage, a failure will occur in which all the AC voltage stages fail. Generally, the rectifier in the AC voltage block is burned out. One of the two rectifier diodes will have a large measurement error in the AC voltage block or failure of the AC voltage block.) Or, in other words, the gear switch has poor contact, or the gear switch is short-circuited, causing the voltage divider resistor or the rectifier diode to burn. Cause AC voltage gear failure, because the current gear switches are PCB switches.
Let me write down some of my experience in repairing multimeters. It can measure alternating current, but it is not suitable for long-term measurements. The main purpose is to determine whether the 220V or 380V voltage is normal. However, if the AC voltage is measured frequently or for a long time, it will have an impact on the voltage dividing resistor and rectifier diode of the MF-47 AC voltage block. I used the above-mentioned MF-47 pointer multimeter AC voltage block. Possible faults have been noted.
