Aniqlashda ba’zi tafsilotlarga e’tibor berish vaqti keldi PCB kartasi, shuning uchun mahsulot sifatini ta’minlash uchun yaxshiroq tayyorgarlik ko’rish. PCB kartasini aniqlayotganda, biz quyidagi 9 sog’lom fikrga e’tibor qaratishimiz kerak.

1. Izolyatsiya transformatorisiz PCB kartasini aniqlash uchun pastki plastinkadagi jonli televidenie, audio, video va boshqa uskunalar bilan aloqa qilish uchun erga ulangan sinov uskunasidan foydalanish qat’iyan man etiladi.

To’g’ridan -to’g’ri elektr uzatish transformatorlari bo’lmagan televizor, audio va video qurilmalarni to’g’ridan -to’g’ri sinovdan o’tkazmang. Umuman olganda, magnitafonda kuch transformatori mavjud bo’lsa -da, maxsus yoki katta quvvatga ega bo’lganida, televizor yoki stereo uskunalar haqida ko’p narsa bilmaydi, avval mashinaning shassisining zaryadlanganligini aniqlang, aks holda juda zo’r va polga tirik. Televizor, audio va boshqa uskunalarning elektr ta’minoti sxemasi, integral mikrosxemaga tarqalishi, keyingi uzilishlar.

2. PCB kartasini aniqlashda elektr lehimlanadigan temirning izolyatsiyalash ko’rsatkichlariga e’tibor bering

Lehimlash temiridan jonli quvvat bilan foydalanishga yo’l qo’yilmaydi. Lehimlash temirining tirik emasligiga ishonch hosil qilish uchun, lehim temirining qobig’ini maydalash yaxshidir. MOS sxemasi ehtiyotkorroq bo’lishi kerak va past kuchlanishli 6-8V kuchlanishli dazmoldan foydalanish xavfsizroqdir.

3. PCB kartasini aniqlashdan oldin, biz integratsiyalashgan kontaktlarning zanglashiga olib keladigan sxemasining ishlash tamoyilini tushunishimiz kerak

Integral mikrosxemalarni tekshirish va ta’mirlashdan oldin, avvalo, integral mikrosxemalar, ichki zanjirlar, asosiy elektr parametrlari, har bir pinning roli va normal kuchlanish, pinning to’lqin shakli va periferikdan tashkil topgan sxemaning ishlash printsipi bilan tanishishimiz kerak. komponentlar. Agar bu shartlar mavjud bo’lsa, tahlil qilish va tekshirish ancha oson bo’ladi.

4, sinov PCB kartasi pinlar orasidagi qisqa tutashuvga olib kelmaydi

Voltajni o’lchash yoki osiloskop probining to’lqin shakli, qalam yoki zond siljish tufayli integratsiyalashgan kontaktlarning pimlari o’rtasida qisqa tutashuvni keltirib chiqarmaydi, o’lchash uchun periferik bosma pallasining pimlari bilan to’g’ridan -to’g’ri bog’lanish yaxshidir. Har qanday oniy qisqa tutashuv INTEGRATED sxemasiga osonlikcha zarar etkazishi mumkin, shuning uchun tekis qadoqlangan CMOS integral mikrosxemalarini sinab ko’rishda ehtiyot bo’lish kerak.

5, detection PCB board test instrument internal resistance should be large

Integral mikrosxemalar pinlarining doimiy kuchlanishini o’lchashda ichki qarshiligi 20K ω /V dan yuqori bo’lgan multimetrdan foydalaning; aks holda, ba’zi pinli kuchlanishlar uchun katta o’lchov xatolar bo’ladi.

6. PCB kartasini aniqlashda quvvat integratsiyalashgan sxemasining issiqlik tarqalishiga e’tibor bering

Power integrated circuits should have good heat dissipation and should not be allowed to work in a high power state without heat sink.

7, tenglikni kartasi qo’rg’oshini aniqlash oqilona bo’lishi kerak

Integral elektron ichidagi shikastlangan qismni almashtirish uchun periferik komponentlarni kiritish zarur bo’lsa, kichik qismlarni tanlash kerak, va keraksiz parazitar birikmalarning oldini olish uchun, ayniqsa, ovoz kuchaytirgichning integrallashgan davri orasidagi topraklama uchi bilan shug’ullanish uchun simlar oqilona bo’lishi kerak. oldindan kuchaytirgich davri.

8. PCB kartasining payvandlash sifatini ta’minlang

Payvand chindan ham payvandlanganda, lehim va gözeneklarning to’planishi virtual payvandlashga sabab bo’ladi. Payvandlash vaqti odatda 3 soniyadan oshmaydi va lehimlanadigan temirning quvvati taxminan 25 Vt. Ehtiyotkorlik bilan tekshirish uchun integral mikrosxemalar payvandlangan, pimlar o’rtasida qisqa tutashuv mavjudligini o’lchash, lehimning yopishmasligi hodisasini tasdiqlash va keyin quvvat manbaini yoqish uchun ohmmetrdan foydalanish yaxshidir.

9, tenglikni kartasini aniqlash integratsiyalangan kontaktlarning zanglashiga osonlikcha aniqlanmaydi

Do not easily judge that the integrated circuit is damaged. Because the vast majority of integrated circuits are directly coupled, once a circuit is abnormal, it may lead to multiple voltage changes, and these changes are not necessarily caused by the damage of the integrated circuit, and in some cases, the measured pin voltage is consistent with or close to the normal value, it may not be able to show that the integrated circuit is good. Because some soft faults do not cause changes in DC voltage.

PCB board debugging method

Yaqinda olib kelingan yangi tenglikni kartochkasi uchun, avvalo, bortda muammolar bor -yo’qligini, masalan, aniq yoriqlar, qisqa tutashuv, ochiq tutashuv va boshqa hodisalarni kuzatishimiz kerak. If necessary, check that the resistance between the power supply and the ground is large enough.

Yangi tuzilgan elektron karta uchun disk raskadrovka ko’pincha ba’zi qiyinchiliklarga duch keladi, ayniqsa karta kattaroq bo’lsa, ko’proq komponentlar, qanday boshlashni bilmaydilar. Ammo, agar siz disk raskadrovka qilishning oqilona usulini o’zlashtirsangiz, disk raskadrovka yarim harakat bilan ikki barobar natija beradi.

PCB board debugging procedure

1. For the new PCB board just brought back, we should first roughly observe whether there are problems on the board, such as whether there are obvious cracks, whether there are short circuits, open circuits and other phenomena. If necessary, check that the resistance between the power supply and the ground is large enough.

2, keyin esa o’rnatish komponentlari. Mustaqil modullar, agar siz ularning to’g’ri ishlashiga ishonch hosil qilmasangiz, ularning hammasini emas, balki o’rnatishning bir qismini (kichik zanjirlar uchun birdaniga o’rnatish mumkin) o’rnatganingiz ma’qul, shuning uchun nosozlikni aniqlash oson. Agar siz muammolarga duch kelsangiz, qanday boshlashni bilmasligingiz uchun.

Generally speaking, you can install the power supply part first, and then check whether the power supply output voltage is normal. Agar siz elektr tarmog’ini yoqishda ishonchingiz komil bo’lmasa (agar shunday bo’lsa ham, sizga sug’urta qo’shishni maslahat berishadi), siz oqimni cheklash funktsiyali sozlanishi voltaj regulyatoridan foydalanishingiz mumkin.

Birinchidan, oqim himoyasini oldindan sozlang, so’ng regulyatorning quvvat manbai asta -sekin ko’tariladi va kirish oqimi, kirish voltaji va chiqish voltaji kuzatiladi. If no overcurrent protection occurs and the output voltage is normal, the power supply is OK. Aks holda, elektr ta’minotini uzing, nosozlikni toping va elektr ta’minoti normal bo’lmaguncha yuqoridagi amallarni takrorlang.

3, keyin asta -sekin boshqa modullarni o’rnating, har bir modul o’rnatildi, sinovdan o’tkazildi, yuqoridagi amallarga muvofiq yoqildi, dizayndagi xatolar yoki o’rnatish xatolaridan kelib chiqqan holda komponentlarning haddan tashqari tokini va yonib ketishini oldini olish uchun.

Noto’g’ri PCB kartasining echimini toping

1. Noto’g’ri PCB kartasini topish uchun kuchlanishni o’lchang

The first thing to confirm is whether the voltage of the chip power pin is normal, and then check whether all kinds of reference voltage is normal, and whether the working voltage of each point is normal. A typical silicon triode, for example, will have a BE junction voltage of around 0.7V and a CE junction voltage of around 0.3V or less. Agar triodda 0.7V dan yuqori bo’lgan BE kuchlanishli kuchlanish bo’lsa (Darlington naychalari kabi maxsus triodlar bundan mustasno), BE birikmasi ochiq bo’lishi mumkin.

2, signal injection method to find the fault PCB board

Add the signal source to the input end, and then measure the waveform of each point in turn to see whether it is normal to find the fault point. Ba’zan biz oddiy usuldan ham foydalanamiz, masalan, audio -video kuchaytirgich sxemalarida tez -tez ishlatiladigan chiqish terminalida reaktsiya bor -yo’qligini bilish uchun kirish terminaliga tegish uchun cımbız tutish. bu usul issiq tayanch plitalari yoki yuqori kuchlanishli davrlarda qo’llanilishi mumkin emas, aks holda u elektr toki urishiga olib kelishi mumkin). Agar teginishdan oldin hech qanday reaktsiya bo’lmasa va teginishdan keyin reaktsiya bo’lsa, bu muammo avvalgi darajada ekanligini ko’rsatadi, tekshirishga e’tibor qaratish lozim.

3. Noto’g’ri PCB plitalarini topishning boshqa usullari

There are many other ways to find trouble spots, such as seeing, hearing, smelling, and touching.

“Qarang” – bu tarkibiy qismlarning yorilishi, qorayishi, deformatsiyasi va boshqalar kabi aniq mexanik shikastlanishlari bor -yo’qligini ko’rish;

“Eshiting” – bu ishning ovozi normal bo’ladimi, masalan, ba’zi narsalar ringda jiringlamasligi, halqa jiringlamasligi yoki tovush normal emasligini tinglash;

“Hidi” – tajribali elektron parvarishlash xodimlari uchun bu hidga juda sezgir bo’lgan yonish hidi, kondansatör elektrolitlarining ta’mi kabi hid bor yoki yo’qligini tekshirish;

“Touch” is to use the hand to test whether the temperature of the device is normal, such as too hot, or too cold.

Ba’zi quvvat qurilmalari, ishlayotganda, isitiladi, agar teginish sovuq bo’lsa, siz asosan ishlamayapti deb hukm qilishingiz mumkin. But if it’s hot where it shouldn’t be or too hot where it should be, that’s no good. General power triode, voltage regulator chip, etc., working in 70 degrees is completely no problem. 70 daraja nimani anglatadi? If you can hold your hand on it for more than three seconds, the temperature is probably below 70 degrees (be careful not to burn your hand).