Pogosti odpravljanje težav in vzdrževanje nasveti za digitalni multimetri
1. If all gears fail to work, focus on checking the power circuit and A/D converter circuit. When checking the power supply part, you can remove the laminated battery, press the power switch, connect the positive test lead to the negative power supply of the meter under test, and connect the negative test lead to the positive power supply (for a digital multimeter). Turn the switch to the diode measurement position. If it displays is the forward voltage of the diode, it means that the power supply part is good. If the deviation is large, it means there is a problem with the power supply part. If there is an open circuit, focus on checking the power switch and battery leads. If a short circuit occurs, you need to use the circuit breaking method to gradually disconnect the components using power, focusing on checking the operational amplifier, timer, A/D converter, etc. If a short circuit occurs, generally more than one integrated component will be damaged. The A/D converter can be checked at the same time as the basic meter, which is equivalent to the DC meter of an analog multimeter. The specific inspection method is:
(1) The meritve razpon od merilnik pod preskus is obrnjen do najnižji DC napetost doseg;
(2) Ukrep w, ali the working napetost of the A/D converter is normalno. According to the A/D converter model uporabljen in the table, ujemajoče do do V+ pin and COM pin, wter the the measured value is consistent with njegov tipično vrednost.
(3) Ukrep the reference napetost of the A/D pretvornik. The reference napetost od pogosto uporabljeno digitalno multimetrsko je na splošno 100mV ali 1V, to is, 2c the DC napetost med VREF+ and COM. If it odstopa od 100mV or 1V, use an zunanji potenciometer. Make adjustments.
(4) Check the display number whose input is zero, short-st the positive terminal IN+ and the negative terminal IN- of the A/D converter, so that the input voltage Vin=0, the meter displays "000" or "{00}}}}}}".
(5) Check the monitor for full bright strokes. Short-circuit the test terminal TEST pin and the positive power supply terminal V+, so that the logic ground becomes high potential and all digital circuits stop working. Since DC voltage is applied to each stroke, all strokes light up and the alignment meter displays "1888", and the alignment meter displays "18888". If there are missing strokes, check whether there is poor contact or disconnection between the corresponding output pin of the A/D converter, the conductive adhesive (or connection), and the display.
2. If there is a problem with some files, it means that the A/D converter and power supply part are working normally. Because the DC voltage and resistance files share a set of voltage dividing resistors; the AC and DC currents share a shunt; the AC voltage and AC current share a set of AC/DC converters; others such as Cx, HFE, F, etc. are composed of independent converters. . Understand the relationship between them, and then according to the power diagram, it is easy to find the fault location. If the measurement of small signals is inaccurate or the displayed numbers fluctuate greatly, focus on checking whether the contact of the range switch is good.
3. If the measurement data is unstable, and the value always increases cumulatively, short-circuiting the input terminal of the A/D converter, and the displayed data is not zero, it is generally caused by poor performance of the 0.1μF reference capacitor.
Osnovano na the zgoraj analiza, the osnovno naročilo of popravilo a digitalno multimeter should be: digital meter glava → DC napetost → DC tok → AC napetost → AC tok → upor doseg (vključno z buzzer and check diode pozitivna napetost padec) → Cx → HFE , F, H, T, etc. But don't be too mehanski. Nekateri očitni problemi lahko be obravnavajo z prvi. Ampak kdaj ustvarjanje prilagajanje, vi mora slediti zgornji postopki.
V kratko, po pravilno testiranje od a okvarjeno multimeter, mora najprej analizirati mogoče lokacija od napaka, in potem najti the napaka lokacija ustrezati do to vezje diagram za zamenjavo in popravilo. Ker the digital multimeter is a relativno na natančna instrument, the komponente mora biti zamenjana z komponente z enaka parametra. Zlasti kdaj zamenjava the A/D pretvornik, a razdelilnik to je bil strog pregledan pregledan s proizvajalec mora biti uporabljen, drugače napake bo in the zahtevani rezultati bo ne ne dosežen. Točnost. The novo zamenjano A/D pretvornik tudi potrebe to to be preverjeno v skladu z do metodo omenjeno nad , in it must not be zaupanja vredno samo ker je je novo.
At sedanjost, tam so mno domače domači proizvajalci digitalno multimetrsko, in njihova kakovost varia. It je težko naj naj kakovost težave z obojestransko bakreno oblečeno plošče med popravili. Kdaj izolacija trdnost of smola plošča is ni dovolj, the main manifestacija is to the napaka is velika kdaj merjenje visoka napetost, in it mora biti razločen od the upor sprememba napetost delitev upor upor kdaj popravilo. V to primer, it is najboljše do uporaba to toko prelom metoda naj naj napaka točka. The sežgani in karbonizirani deli mora biti očiščeni do izpolniti izolacija zahteve. Kdaj the signal not be vhod za do the prelom of the prehod luknja v the dvostranska povezava, it je enostavno do zmedeno zmedeno z the okvarjeno prenos stikalo in težko to ločeno. Za to vrsta napaka, the short circuit metoda bi morala be rabljeno do najdi the fault point.
