The multimeter stick is short-circuited and the multimeter does not return to the zero point.
There are a variety of reasons, from outside to inside, from simple to complex step by step to find.
1, release the pen, observe the pointer in the left starting position can be zeroed. If you can not return to zero, use your fingernail to insert the root of the adjusting pointer at the Bakelite to adjust the eccentric lever to zero, adjust the non-responsive, internal small rod broken. Can be zeroed, will be placed on the desktop table hand cupped on both sides of the desktop shaking left and right, observe the needle from the left to the right midway there is no obstruction. There is an obstruction that the pointer scrapes the dial or scrapes the glass. Disassemble and repair. No obstacles, turn to the next step.
2,Adjust the zeroing knob to the right to the end, that is, the maximum zeroing correction. Red pen pointing at the black pen socket metal seat, black pen pointing at the red pen metal seat, equivalent to two pens in parallel, can be zeroed, indicating that the pen has poor contact, check and eliminate. Can not be zeroed, turn to the next step
3, open the bottom battery box cover, take out the 1.5-volt battery, the multimeter will be placed in the DC voltage 2.5-volt gear. Measure the battery is not 1.5 volts, not enough, replace. Voltage is enough, observe the battery box positive and negative shrapnel whether oxidation corrosion, if so, remove. No corrosion, adjust the shrapnel, enhance the contact with the battery, load the battery. See if it can be zeroed. Can not be zeroed, the next step.
4, open the meter box, observe the zero line winding potentiometer centre contact piece, there is no poor contact or potentiometer resistance wire broken. No problem, the next step
5, check the shift switch ohm gear position contact, observe the switch has no poor contact. No problem, next step.
6, observe the small wire-wound resistor of ohm x1 gear, there is no burnt.
If the first five steps to check are normal, the problem is the sixth step, usually people do not pay attention, mistakenly ohm gear to measure the voltage, the internal small wire wound resistor burned, resulting in can not be zeroed. Accurately matched with the same value of resistance, the fault will be eliminated.
