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First of all,to thoroughly understand the principles of some typical circuits,purely in the heart.Drawings are dead, the brain in the mind is alive, able to analogue, able to reason, able to touch, a hundred passes.
1.How can I repair pcb boards without drawings?
First of all, to thoroughly understand the principles of some typical circuits, purely in the heart.Drawings are dead, the brain is alive in the mind, to be able to analogue, to reason, to be able to touch, a pass. For example, switching power supply, always away from the oscillator circuit, switching tube, switching transformer these,check the circuit to see whether there is no vibration, capacitance has no damage, the triode, diode body has no damage, regardless of what comes across the switching power supply, the operation of the operation are almost the same, do not have to force circuit diagrams; such as a variety of operational amplifiers composed of analogous circuits, even if it changes a thousand in the ‘virtual short’ and ‘short’ and ‘short’ and ‘short’ and ‘short’ and ‘short’ and ‘short’ and ‘short’. Virtual short’ and “virtual break” on the basis of reasoning, but also can have a head of the line,the section intricate analysis, get a clear understanding of the white.
2.Necessary testing equipment is required.
If you will repair as their own work, then a certain amount of equipment is necessary. Soldering iron, multimeter, commonly used disassembly things, brand not too bad. If you are in a position to get a 100M dual-trace oscilloscope, and then if you are in a position to set up an online repair tester.
3.To study the repair sequence
Study the order of inspection and repair to find the shortest way to deal with the problem, to avoid randomly stabbing and dismantling, repair can not be, resulting in the expansion of the problem. Repair is like a doctor to see a doctor, also studied a ‘look, smell, ask and cut’. ‘Look’ that is, check the appearance of the faulty board to see whether there are significant traces of damage above, there are no components burned black, burst, circuit boards have no corrosion caused by broken lines, leakage, capacitance has no leakage of liquid, the top of the top has no rise, etc.; “Smell” sniffing with the nose to smell the smell of something burnt, no smell of something burnt, no smell of something burnt, no smell of something burnt, no smell of something burnt, no smell of something burnt,no smell of something burnt, no smell of something burnt,no smell of something burnt. There is no something burning smell, the smell is announced from where; ‘ask’ is very important to specifically ask the person in question, the equipment out of trouble at the time of the situation, from the status of reasoning may be faulty parts or components; ‘cut’ that is, the use of certain detection instruments and means, and the power and powerlessness of two kinds of Divided into two conditions of power and powerless, view circuit parts or components of the resistance, voltage, waveforms, etc., will be good and bad circuit board comparison test, observe the difference in parameters.
Repair circuit boards
4.Circuit board small resistance bad, first straight look at the small resistance specification mark, find the same specifications of small resistance instead of 40 watts of soldering iron to heat the circuit board on the bad resistance welding branding down, installed with the same specifications of the small resistance, with the soldering iron, solder welded firmly and pick up and check whether the circuit board and other components touch each other, such as the bad resistance to burn black, specifications are not clear, it is necessary to look at the circuit diagram to confirm that there is no drawing, the available small resistors instead of the method of measuring one by one. Qualified performance.
5.Use a multimeter to test, there should be two solder joints are through, or find a board to determine the power and ground pins of the chip, test which solder joints and they are through, you can confirm the positive and negative poles.
6.The power supply board does not respond, indicating that the components are damaged!
Pipeline one, looking for TV manufacturers for after-sales maintenance,after-sales maintenance have special circuit board drawings, measuring the corresponding point of the voltage value, so as to see which point of the circuit is abnormal, replace the corresponding components can be repaired!
Pipeline two, hands-on ability! Circuit board on the lightning and static devices,using a multimeter to measure the circuit board on the TVS tube, whether there is a short circuit. There is also the power supply chip, measure the resistance to ground! A little bit of maintenance!
7.How to repair the board without a drawing?
1）Possibly the video signal is not detected,囙start the blue screen protector and the screen.
(2) may be the screen for a long time so that the screen panel suffered damage,resulting in the screen can not properly carry out a job.
(3) may be a TV, set-top box or DVD player and other equipment through the AV cable connection,AV cable yellow plug is not connected to the standard or plug loose, resulting in the TV can not be normal output video signals, that is, no picture.
4) The voltage may be unstable, resulting in a black screen phenomenon.
(5) may be circuit board problems, resulting in circuit burn,circuit burn will lead to chip problems.
8.The basis of electrical engineering, the basis of circuit analysis, the basis of analog circuit, the basis of digital circuit,the basis of microcontroller, component testing knowledge, maintenance experience cases. These. Want to systematically learn circuit board maintenance technology, need to find some excellent circuit board repair books to learn. Circuit board repair is not a day or two can learn well, patience to build a good theoretical foundation, and then carry out practical exercises, day by day, you can master this technology.