Common Digital Multimeter Troubleshooting and Repair Techniques
Rau cov cuab yeej faulty, thawj kauj ruam yog los xyuas thiab paub qhov txawv ntawm qhov kev ua txhaum yog qhov tshwm sim (tag nrho cov haujlwm tsis tuaj yeem ntsuas) lossis tus kheej (tus kheej lub luag haujlwm lossis tus kheej ntau yam), thiab tom qab ntawd sib txawv qhov xwm txheej thiab daws nws raws li.
Yog tias txhua lub zog tsis tuaj yeem ua haujlwm, lub hwj chim muab hluav taws xob thiab A / D converter circuit yuav tsum tau xyuas kom zoo. Thaum kuaj xyuas cov khoom siv hluav taws xob, tshem tawm cov roj teeb uas tau teem tseg, nias lub hwj huam hloov, txuas qhov kev sojntsuam zoo rau qhov tsis zoo ntawm lub ntsuas hluav taws xob, thiab txuas cov kev sojntsuam tsis zoo rau lub zog zoo (rau digital multimeter). Tig qhov hloov mus rau qhov ntsuas diode. Yog hais tias cov zaub qhia qhov zoo voltage ntawm lub diode, nws qhia tau hais tias lub hwj chim mov yog zoo. Yog tias qhov sib txawv loj, nws qhia tau hais tias muaj teeb meem nrog cov khoom siv hluav taws xob. Yog tias muaj qhov qhib Circuit Court, tsom mus rau kev kuaj xyuas lub hwj chim hloov thiab cov roj teeb coj. Yog tias muaj kev cuam tshuam luv luv, nws yuav tsum siv txoj hauv kev sib tsoo kom maj mam txiav cov khoom siv hluav taws xob, nrog rau kev tsom mus rau kev tshuaj xyuas lub tshuab ua haujlwm, lub sijhawm, thiab A / D converter. Yog hais tias ib tug luv luv Circuit Court tshwm sim, nws feem ntau puas ntau tshaj ib tug integrated tivthaiv. Kev kuaj xyuas A / D converter tuaj yeem ua tiav ib txhij nrog lub ntsuas qhov yooj yim, sib npaug rau DC meter taub hau ntawm analog multimeter. Kev tshuaj xyuas tshwj xeeb:
(1) Tig qhov ntau ntawm cov ntsuas ntsuas mus rau qhov qis tshaj DC voltage theem;
(2) Ntsuas seb qhov kev khiav hauj lwm voltage ntawm A / D converter yog qhov qub. Raws li tus qauv ntawm A / D converter siv nyob rau hauv lub rooj, sib xws rau V + thiab COM pins, sib piv cov nqi ntsuas nrog lawv cov txiaj ntsig zoo saib seb lawv phim.
(3) Ntsuas qhov siv voltage ntawm A / D converter. Feem ntau siv digital multimeter siv voltage feem ntau yog 100mV lossis 1V, uas ntsuas DC voltage ntawm VREF + thiab COM. Yog tias nws deviates ntawm 100mV lossis 1V, nws tuaj yeem hloov kho los ntawm lwm lub potentiometer.
(4) Txheeb xyuas tus lej xov tooj nrog xoom input, luv Circuit Court qhov zoo davhlau ya nyob twg IN + thiab qhov tsis zoo davhlau ya nyob twg IN - ntawm A / D converter kom cov input voltage Vin=0, thiab lub ntsuas yuav tso saib "{{4 }}.0" or "00.00".
(5) Tshawb xyuas cov teeb ci ntsa iab ntawm lub monitor. luv luv Circuit Court xeem davhlau ya nyob twg TEST tus pin mus rau qhov zoo lub hwj chim davhlau ya nyob twg V +, ua rau lub logic hauv av los ua siab thiab tag nrho cov digital circuits yuav tsum tsis txhob ua hauj lwm. Vim tias qhov hluav taws xob ncaj qha tam sim no siv rau txhua qhov mob stroke, tag nrho cov strokes tau teeb pom kev zoo thiab cov lus sib dhos qhia "1888" thiab "18888". Yog tias muaj qhov tshwm sim tshwm sim tsis zoo, xyuas seb puas muaj kev sib cuag tsis zoo lossis kev cuam tshuam ntawm tus pin tso zis ntawm A / D converter thiab cov nplaum nplaum (lossis thaiv), thiab cov zaub.
Yog tias muaj teeb meem nrog ib tus neeg cov ntaub ntawv, nws qhia tau hais tias ob qho tib si A / D converter thiab lub hwj chim mov ua haujlwm zoo. Vim hais tias DC voltage thiab kuj ntau yam sib koom ua ke ntawm voltage divider resistors; AC / DC tam sim no sib koom shunt; AC voltage thiab AC tam sim no sib koom ua ke ntawm AC / DC converters; Lwm yam xws li Cx, HFE, F, thiab lwm yam yog tsim los ntawm cov converters ywj siab. Los ntawm kev nkag siab txog lawv txoj kev sib raug zoo thiab xa mus rau daim duab hluav taws xob, nws yooj yim los nrhiav qhov tsis raug. Yog tias qhov ntsuas ntawm cov cim me me tsis raug lossis cov lej pom tau hloov pauv ntau, nws yog ib qho tseem ceeb uas yuav tau xyuas seb qhov kev sib cuag ntawm qhov hloov pauv yog qhov zoo.
Yog tias qhov ntsuas cov ntaub ntawv tsis ruaj khov thiab cov txiaj ntsig ib txwm sib sau, thiab qhov chaw tawm tswv yim ntawm A / D converter luv luv, thiab cov ntaub ntawv tso tawm tsis yog xoom, nws feem ntau tshwm sim los ntawm kev ua haujlwm tsis zoo ntawm 0.1 μ F siv capacitor.
