Lokaci ya yi da za a kula da wasu cikakkun bayanai a cikin gano Kwamitin PCB, so as to better prepare to ensure product quality. When detecting PCB board, we should pay attention to the following 9 common sense.

1. It is strictly forbidden to use the grounded test equipment to contact the live TV, audio, video and other equipment on the bottom plate to detect the PCB board without the isolation transformer.

Kada ku gwada TV, sauti, da na’urorin bidiyo kai tsaye ba tare da masu rarraba wutar lantarki da keɓaɓɓun na’urori ba. Kodayake gabaɗaya mai rikodin yana da mai canza wutar lantarki, lokacin da aka fallasa shi zuwa musamman musamman ko babban ƙarfin fitarwa na yanayin samar da wutar lantarki ba su da masaniya sosai game da TV ko kayan aikin sitiriyo, da farko bayyana cewa ana cajin chassis ɗin injin, in ba haka ba mai sauƙin gaske da rayuwa mai rai. TV, sauti da sauran hanyoyin samar da wutar lantarki na kayan aiki, ya bazu zuwa da’irar da aka haɗa, ƙarin ɓarna.

2. Kula da aikin rufi na baƙin ƙarfe na siyarwa lokacin gano allon PCB

Ba a yarda a yi amfani da baƙin ƙarfe tare da ikon rayuwa ba. Don tabbatar da cewa baƙin ƙarfe ba shi da rai, zai fi kyau a murƙushe harsashin ƙarfe na ƙarfe. MOS Circuit yakamata yayi taka tsantsan, kuma yana da aminci don amfani da baƙin ƙarfe mai ƙarancin wuta tare da 6-8V.

3. Kafin gano allon PCB, yakamata mu fahimci ƙa’idar aiki na haɗaɗɗiyar kewaye da kewaye

Kafin dubawa da gyara madaidaiciyar madaidaiciya, ya kamata mu fara saba da ayyukan haɗaɗɗun da’irori, da’irori na ciki, manyan sigogi na lantarki, rawar kowane fil da madaidaicin ƙarfin lantarki, kaɗawar fil da ƙa’idar aiki na da’irar da aka haɗa ta gefe. aka gyara. Idan waɗannan sharuɗɗan sun kasance, bincike da dubawa sun fi sauƙi.

4, gwajin PCB gwajin baya haifar da gajeren zango tsakanin fil

Ƙarfin ƙarfin lantarki ko ƙirar gwajin oscilloscope, alkalami ko bincike ba sa haifar da ɗan gajeren zango tsakanin fil ɗin haɗaɗɗiyar da’irar saboda zamewa, yana da kyau a haɗa kai tsaye tare da fil na madaurin bugawa na gefe don aunawa. Duk wani gajeren gajeren zango na iya lalata INTEGRATED circuit cikin sauƙi, don haka yakamata a kula sosai yayin gwajin fakitin fakitin CMOS.

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

Lokacin auna ƙarfin wutar lantarki na DC na fil ɗin hanyoyin haɗin kai, yi amfani da multimeter wanda juriya na ciki ya fi 20K ω /V; in ba haka ba, za a sami manyan kurakuran ma’auni don wasu voltages na fil.

6. Kula da watsawar zafi na haɗaɗɗiyar wutar lantarki lokacin gano allon PCB

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

7, gano gubar jagoran PCB yakamata ya zama mai ma’ana

Idan ya zama dole don ƙara abubuwan haɗin gwiwa don maye gurbin ɓangaren da ya lalace a cikin haɗaɗɗiyar da’irar, yakamata a zaɓi ƙananan abubuwan haɗin, kuma wayoyi yakamata su zama masu dacewa don gujewa haɗuwar parasitic ba dole ba, musamman don magance ƙarshen ƙasa tsakanin amplifier mai haɗa sauti da da’irar preamplifier.

8. Tabbatar ingancin walda na hukumar PCB

Lokacin da aka haɗa walda da gaske, tarin solder da pores suna da sauƙi don haifar da walda ta kama -da -wane. The welding time is generally not more than 3 seconds, and the power of the soldering iron is about 25W. The integrated circuit has been welded to carefully check, it is best to use ohmmeter to measure whether there is a short circuit between the pins, confirm no solder adhesion phenomenon and then switch on the power supply.

9, gano allon PCB ba sauƙaƙe ƙayyade lalacewar haɗin kewaya ba

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

Don sabon kwamitin PCB da aka dawo da shi, da farko yakamata mu lura sosai ko akwai matsaloli a cikin jirgin, kamar ko akwai bayyanannun fasa, ko akwai ɗan gajeren zango, da’irar buɗewa da sauran abubuwan mamaki. If necessary, check that the resistance between the power supply and the ground is large enough.

For a newly designed circuit board, debugging often encounter some difficulties, especially when the board is larger, more components, often do not know how to start. Amma idan kun ƙware hanyar ɓarna mai ma’ana, cire kuskure zai sami sakamako sau biyu tare da rabin ƙoƙarin.

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, sannan kayan aikin shigarwa. Module masu zaman kansu, idan ba ku tabbatar da cewa suna aiki yadda yakamata ba, yana da kyau kada a shigar da dukkan su, amma wani ɓangare na shigarwa (don ƙananan da’irori, ana iya shigar da su gaba ɗaya), don haka yana da sauƙi don tantance laifin kewayon, don haka lokacin da kuka haɗu da matsaloli, ba ku san yadda ake farawa ba.

Generally speaking, you can install the power supply part first, and then check whether the power supply output voltage is normal. Idan ba ku da tabbacin lokacin kunnawa (koda kuwa kun kasance, ana ba ku shawara ku ƙara fuse, idan da hali), kuna iya yin la’akari da amfani da mai daidaita wutar lantarki mai daidaitawa tare da aikin iyakancewa na yanzu.

Da farko saita saiti na yanzu, sannan ƙimar ƙarfin wutar lantarki mai ba da wutar lantarki a hankali a hankali, da saka idanu kan shigarwar, ƙarfin shigar da ƙarfin lantarki. If no overcurrent protection occurs and the output voltage is normal, the power supply is OK. In ba haka ba, cire haɗin wutan lantarki, nemo laifin, kuma maimaita matakan da ke sama har sai wutar lantarki ta zama ta al’ada.

3, sannan sannu a hankali shigar da wasu kayayyaki, kowane shigar da aka saka, iko akan gwaji, kunnawa bisa ga matakan da ke sama, don gujewa wuce gona da iri da ƙona abubuwan saboda kurakuran ƙira ko kurakuran shigarwa.

Nemo maganin kwamitin PCB mara kyau

1. Auna ƙarfin lantarki don nemo allon PCB mara kyau

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. If a triode has a BE junction voltage greater than 0.7V (except for special triodes such as Darlington tubes), the BE junction may BE open.

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. Wani lokaci kuma za mu yi amfani da hanya mafi sauƙi, kamar riƙe tweezer don taɓa tashar shigarwa a duk matakan don ganin ko akwai wani martani a tashar fitarwa, wanda galibi ana amfani da shi a cikin hanyoyin sauti da bidiyo (amma ya kamata a lura cewa ba za a iya amfani da wannan hanyar ba a cikin da’irori tare da faranti na zafi mai zafi ko da’irar ƙarfin lantarki, in ba haka ba yana iya haifar da girgiza wutar lantarki). If there is no reaction before the touch, and there is a reaction after the touch, it shows that the problem is in the previous level, should focus on inspection.

3. Other methods for finding faulty PCB boards

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

“Look” is to see whether there is obvious mechanical damage to components, such as rupture, blackening, deformation, etc.;

“Listen” is to listen to whether the sound of work is normal, such as some things should not ring in the ring, the ring does not ring or the sound is not normal;

“Ƙamshi” shine a bincika ko akwai ƙamshi, kamar ƙamshin ƙonawa, ɗanɗano mai ƙarfin lantarki, ga ƙwararrun ma’aikatan kula da lantarki, yana da matuƙar kula da waɗannan ƙanshin;

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

Some power devices, when working, heat, if it is cold to the touch, you can basically judge that it does not work. 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. Menene digiri 70 ke nufi? 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).