The 2.8v voltage measurement method should first align the range switch with the five stops marked V (the AC voltage should be aligned with the gear of the AC voltage when testing the DC voltage, and the DC voltage should be aligned with the gear of the DC voltage when testing the DC voltage).
When measuring voltage, the meter pen should be connected to the circuit being measured. Select a suitable range position according to the approximate value of the circuit under test. Each dry battery has a maximum value of 1.5V, so it can be placed in a 5V range. At this time, the 500 full scale reading of the watch hand on the panel should be read as 5. That's 100 times smaller. If the hand is pointed at 300 scale, it is read as 3V. Note that the value indicated by the tip of the range switch is the corresponding value of the full scale reading of the dial on the watch head, and the real value can be read as long as the meter is converted accordingly. The measurement results are read in this way in all ranges switches except the resistance.
In the actual measurement, when the approximate value of the measured voltage cannot be determined, the switch can be shifted to the maximum range, and then the range can be reduced to the appropriate position. When measuring DC voltage should pay attention to positive and negative polarity, if the pen is reversed, the watch hand will be reversed. If you do not know the positive and negative polarity of the circuit, you can put the range of the Manda meter in the maximum gear, and try it quickly on the circuit under test to see how the pen deflect, you can judge the positive and negative polarity.
The 2.8V voltage is generally the voltage of pin 1 and pin 26 of the digital multimeter 7106 chip. It can be tested with the 10V DC voltage of the multimeter. Connect the red watch pen with 1 pin, and the black watch pen with 26 pins.