How to use a pointer multimeter to detect whether the speaker is good or bad
Turn the pointer multimeter to the ohm position, and then turn the multimeter to one ohm, and randomly connect the pointer multimeter, red test lead, and black test lead to zero, so that the measurement is accurate. No need to measure the speaker, just turn the multimeter to zero. To one ohm, the test lead can be connected to the positive or negative pole of a speaker at will. Just touch the other pole of the speaker with another test lead. As long as you hear the sound of clicking, it proves that the speaker is good. On the contrary, it is silent. Turned out to be bad. The above is the measurement method of using a pointer multimeter to judge whether the speaker is good or bad. To judge whether the speaker is good or not, it is best to use a pointer multimeter to measure one ohm.
It is enough to use the detection resistance gear to detect the speaker. The driver of the speaker is a copper wire winding coil. According to the impedance needs, it can be divided into 4 ohms, 8 ohms, etc., as long as the current passes through it is good. This is the knowledge I learned 55 years ago, when I assembled seven-tube transistor semiconductor radios and repaired transistor TVs. Now they are all integrated circuit chips, and the knowledge has been updated, but the principle of the speaker has not changed much.
Digital Multimeter History
Digital multimeters have developed slowly through history. Early multimeters used a dial that deflected the pointer with a magnet, the same as the classic galvanometer; modern ones use a digital display provided by an LCD or VFD (Vacuum fluorescent display). Analog multimeters are not hard to find on the used market, but they are less accurate due to bias in both zeroing and accurate readings from the instrument panel. Some analog multimeters use vacuum tubes to amplify the input signal. Multimeters of this design are also called vacuum tube voltmeters (VTVM, VacuumTubeVoltMeters) or vacuum tube multimeters (VTMM, VacuumTubeMultimeters). Modern multimeters are all digitized and are specifically called digital multimeters (DMM, DigitalMultiMeter). In this device, the measured signal is converted into a digital voltage and amplified by a digital preamplifier, and then the value is directly displayed by the digital display; thus avoiding the deviation caused by parallax when reading. Likewise, better circuitry and electronics improve measurement accuracy. The basic accuracy of the old analog instrument is between 5[%] and 10[%], while the modern portable digital multimeter can reach ±0.025[%], and the accuracy of the bench equipment is as high as one millionth.
