Tiswija Tekniki għal Diġitali Multimetri
1. If all gears cannot work, the focus should be on checking the power circuit and A/D converter circuit. When checking the power supply, remove the stacked battery, press the power switch, connect the power switch, connect the positive lead to the negative power supply of the measured meter, and connect the negative lead to the positive power supply (for a digital multimeter). Turn the switch to the measurement position of the secondary transistor. If the display shows the positive voltage of the secondary transistor, it indics that the power supply is is good. If the deviation is large, it indics that there is a problem with the power supply.
The A/D converter can be checked simultaneously with the basic meter, li is equivalent the DC meter head of an analog multimeter. The specific inspection method is:
1) Dawwar il-firxa ta ' il imkejjel metru għal l-inqas livell ta' DC vultaġġ ;
2) Miżura jekk il xogħol vultaġġ ta' A/D konvertitur is normal. Skont il l A/D konvertitur mudell użat in the table, corresponding to the V+pin and COM pin, do the measured values match their typical values.
3) Miżura il referenza vultaġġ ta' A/D konvertitur. At present, the reference voltage of commonly used digital multimeter is generally 100mV or 1V, that is, is, measure the DC voltage between VREF+and COM. If it deviates from 100mV or 1V, it can be adjusted through an external Potentiometer.
4) Check the display number with zero input, short circuit the positive terminal IN+and negative terminal IN - of the A/D converter, so that the input voltage Vin=0}, and the instrument displays "00.0" or "{00}.}.{}}".
5) Iċċekkja il sħiħ bright strokes on the monitor. Short circuit the test pin at the testing end the the positive power supply terminal V+, so that the logic ground becomes high potential and all digital circuits stop working. Due the DC voltage applied applied to each stroke, the allinja meter displays 221888" and the alignment meter meter meter displays meter displays 2218888" when all strokes are lit. If hemm is a lack of stroke, check the corresponding output pin of the A/D converter and the conductive adhesive (or wiring), as well as as jekk hemm is poor contact or disconnection between the A/D converter and the display.
2. If hemm hemm kwistjonijiet ma individwali gerijiet, it jindika li t it jindika li it the A/D converter and power supply are working properly. Because the DC voltage and resistance range share a set of voltage divider resistors; AC and DC current sharing shunt; AC voltage and AC current share a set of AC/DC converters; Other components such as Cx, HFE, F, etc. are composed of independent different converters. Understanding the relationship between them and based on the power diagram, it is easy to locate the faulty part. If the measurement of small signals is not accurate or the displayed number jumps excessively, the focus should be on checking jekk the contact of the range switch is is good.
3. If il kejl data is instabbli u il valur dejjem jakkumula, u l input terminal of the A/D converter is short circuited, and the displayed data is not zero, then it is generally 0.1 μ Caused by poor performance of F's reference capacitor.
Ibbażat fuq il fuq analiżi, the basic repair sequence for a digital multimeter should be: digital meter head → DC voltage → DC current → DC current → AC voltage → AC current → resistance range (inklużi buzzer and checking positive voltage drop of the secondary tube) → Cx → HFE, F, H, T, etc. But it should not be too mechanical. Some obvious problems can be addressed first. But when conducting calibration, it is necessary to follow the above procedure.
