Common Fault Inspection and Repair Techniques for Digital Multimeters
1. Yog tias txhua lub zog tsis ua haujlwm, cov khoom siv hluav taws xob thiab A / D converter Circuit Court yuav tsum tau kuaj xyuas. Thaum kuaj xyuas cov khoom siv hluav taws xob, koj tuaj yeem tshem tawm cov roj teeb laminated, nias lub hwj huam hloov, txuas qhov zoo sojntsuam mus rau qhov tsis zoo ntawm lub 'meter' nyob rau hauv kev sim, thiab qhov kev sojntsuam tsis zoo rau cov khoom siv hluav taws xob zoo (rau digital multimeters), thiab hloov mus rau diode ntsuas iav. Yog hais tias lub diode rau pem hauv ntej voltage yog tso tawm, nws txhais tau hais tias lub hwj chim qhov chaw yog zoo. Yog hais tias qhov sib txawv loj, nws txhais tau hais tias muaj teeb meem nrog lub hwj huam mov. Yog tias muaj qhov qhib Circuit Court, tsom mus rau kev kuaj xyuas lub hwj chim hloov thiab cov roj teeb coj. Yog hais tias muaj ib tug luv luv Circuit Court, nws yuav tsum tau siv lub Circuit Court breaking txoj kev maj mam disconnect lub Cheebtsam uas siv lub hwj chim mov, thiab tsom mus xyuas lub lag luam amplifier, timer thiab A / D converter. Yog hais tias ib tug luv luv Circuit Court tshwm sim, feem ntau ntau tshaj ib tug integrated tivthaiv yog puas. Lub A / D converter tuaj yeem tshawb xyuas tib lub sijhawm raws li qhov ntsuas yooj yim, uas yog sib npaug rau DC meter taub hau ntawm analog multimeter. Txoj kev tshuaj xyuas tshwj xeeb yog:
(1) Qhov ntau ntawm cov ntsuas ntsuas tau hloov mus rau qhov qis tshaj DC voltage iav;
(2) Ntsuas seb qhov ua haujlwm voltage ntawm A / D converter yog qhov qub. Raws li A / D converter qauv siv nyob rau hauv lub rooj, tus coj V + tus pin thiab COM tus pin yog muab piv nrog tus nqi ntsuas los saib seb lawv puas zoo ib yam nrog nws cov nqi raug.
(3) Ntsuas qhov siv voltage ntawm A / D converter. Kev siv hluav taws xob ntawm cov khoom siv digital multimeter feem ntau yog 100mV lossis 1V, uas yog, ntsuas qhov 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 tso saib thaum lub tswv yim yog xoom. Luv luv qhov zoo davhlau ya nyob twg IN + thiab qhov tsis zoo davhlau ya nyob twg IN- ntawm A/D converter los ua qhov input voltage Vin=0, thiab cov twj tso kua mis qhia "00.0" lossis "{{ 6}} 00".
(5) Txheeb xyuas qhov ci ntsa iab tag nrho ntawm cov zaub. Luv luv lub xeem davhlau ya nyob twg TEST tus pin nrog lub zoo fais fab mov davhlau ya nyob twg V + kom lub logical hauv av muaj peev xwm thiab tag nrho cov digital circuits tsis ua hauj lwm. Vim tias qhov hluav taws xob DC siv rau txhua qhov mob stroke, tag nrho cov hlab ntsha tawg yog ci thiab cov lus sib dhos qhia "1888". Lub rooj sib dhos qhia "18888". Yog tias muaj qhov tshwm sim tsis zoo ntawm cov hlab ntsha tawg, xyuas seb puas muaj kev sib cuag tsis zoo thiab kev cuam tshuam ntawm cov khoom sib txuas ntawm tus pin A / D converter thiab cov kua nplaum conductive (lossis cov kab txuas) thiab cov zaub.
2. Yog hais tias muaj teeb meem nrog ib tug neeg cov ntaub ntawv, nws txhais tau hais tias lub A / D converter thiab lub hwj chim mov ua hauj lwm ib txwm. Vim tias cov ntaub ntawv DC voltage thiab cov ntaub ntawv tsis kam sib koom ua ke ntawm voltage divider resistors; AC thiab 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 kev ywj pheej sib txawv converters. Nkag siab txog kev sib raug zoo ntawm lawv, thiab tom qab ntawd raws li daim duab qhia kev siv hluav taws xob, nws yooj yim los nrhiav qhov chaw txhaum. Yog hais tias qhov ntsuas ntawm cov cim me me tsis raug lossis cov duab digital jumps zoo heev, tsom mus xyuas seb qhov kev sib cuag ntawm qhov hloov pauv yog qhov zoo.
3. Yog tias cov ntaub ntawv ntsuas tsis ruaj khov, thiab tus nqi ib txwm nce ntxiv, qhov kev nkag siab kawg ntawm A / D converter yog luv luv, thiab cov ntaub ntawv tso tawm tsis yog xoom, nws feem ntau tshwm sim los ntawm kev ua haujlwm tsis zoo ntawm {{ 2}}.1μF siv capacitor.
Raws li cov kev soj ntsuam saum toj no, cov kev kho yooj yim ntawm ib qho digital multimeter yuav tsum yog: digital meter taub hau → DC voltage → DC tam sim no → AC voltage → AC tam sim no → kuj ntau yam (xws li buzzer thiab xyuas qhov zoo voltage poob ntawm lub diode) → Cx → HFE, F, H, T, thiab lwm yam. Txawm li cas los xij, nws yuav tsum tsis txhob muaj kev siv tshuab ntau dhau. Qee qhov teeb meem pom tseeb tuaj yeem daws tau ua ntej. Txawm li cas los xij, thaum kho, nws yuav tsum ua raws li cov txheej txheem saum toj no.
Nyob rau hauv luv luv, rau ib tug faulty multimeter, tom qab kev ntsuam xyuas kom zoo, qhov chaw ntawm qhov txhaum yuav tsum tau soj ntsuam ua ntej, thiab tom qab ntawd qhov chaw txhaum yuav tsum raug pom raws li daim duab kos rau kev hloov thiab kho. Vim hais tias cov multimeter digital yog cov cuab yeej meej dua, kev hloov ntawm cov khoom yuav tsum tau ua nrog cov khoom ntawm tib qhov tsis zoo, tshwj xeeb tshaj yog thaum hloov A / D converter, cov kev sib xyaw ua ke uas tau soj ntsuam nruj me ntsis los ntawm cov chaw tsim khoom yuav tsum tau siv, txwv tsis pub. yuam kev yuav tshwm sim thiab qhov yuav tsum tau qhov tseeb yuav tsis ua tiav. Cov hloov tshiab A / D hloov tshiab kuj yuav tsum tau kuaj xyuas raws li txoj kev tau piav qhia saum toj no, thiab nws yuav tsum tsis txhob ntseeg vim nws yog tshiab.
