How to use a pointer multimeter to measure whether the heating tube is damaged?
Pointer multimeter to measure AC voltage: connect the black pen to negative or ground, the red pen to +, and the gear to AC~500V. Insert two pens into the digital multimeter. The number pointed to by the pointer must be read corresponding to the maximum range on the right: optional If it is 500V, the reading should look at the row with the largest number marked 50 on the right side of the reading plate. If the pointer points to 20, then the reading is 200V.
Pointer multimeter to measure DC voltage: the same as the digital multimeter, the reading is the same as the above-mentioned AC voltage; when the positive and negative poles of the DC voltage cannot be determined, it can be measured as an AC first, but the reading is not concerned, but the test leads are reversed. In the performance test, see which of the two measurements the pointer is deflected, then the positive and negative polarity that the test pen touched this time is the correct polarity. Then set the gear to the appropriate range of the DC voltage and measure the reading.