LCD TV repair experience and operational skills to share - static flow chart simulation dynamic mode - appliance repair - Huaqiang Electric

Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin

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Mobile phone crystal 3.2*2.5mm 3225 26M (26.000MHZ) 7.5PF 10PPM 20PPM 30PPM

The practical experience and operation skills of LCD TV repair with static flow chart simulation dynamics. Foreword: The author has published a discussion about the type, internal structure, drive connection method, replacement method and attention points of LCD LCD TV backlight. In some cases, the descriptions are relatively simple, lacking basic comprehensiveness and systemicity, and also cover the comprehensive maintenance operation process of multiple failures in an LCD machine. To this end, the author uses this case to take a look at the maintenance operation of the whole machine with the "senior syndrome" thinking: observe the abnormal condition of each plate and component;
Second check: test the work indicators of the board;
Three repairs: repair of faulty panels;
Four exchanges: replacement of faulty panels;
Five reforms: modification of faulty panels, set up the maintenance operation mode of "Five in One", select a representative LCD LCD TV with multiple faults as a practical case, and conduct a comprehensive analysis and repair demonstration. Guidance for fault repair reference.
Case: This is a 40-inch SAMSUNG, model: LN40C530F1F. Usually, there is always a thought before the author overhauls the LCD TV. In medicine, everyone knows that the human liver is a hematopoietic organ, and the heart is a transporting organ for blood circulation. Before the doctor visits the doctor, he usually uses the questions of one question, two views, three models and four tests as the principle of seeing a doctor. The patient is routinely examined. If necessary, further use of advanced methods such as B-ultrasound, CT and MR for computed tomography. Detection. The goal is to obtain the first-hand judgment of the disease reference from the patient to determine the location of the patient's condition. The author calls it the diagnosis and treatment thinking of "Four in One". The author also draws on the reference of this medical thinking and summarizes the "five in one" maintenance operation mode described in "Preface". Because of this, we will make a comprehensive inspection and fault location judgment on the demonstration of the 40-inch SAMSUNG TV related to the fault to achieve the purpose of repair.
Everyone knows that the TV power board is the energy supply center of the whole machine, providing normal working voltage for each component of the TV, like the function of the human liver and the heart, and integrating the functions of the two to provide energy for the various parts of the machine. The main board is a human-like brain in the machine, which has the function of command and control center, and sends work control commands to all parts of the machine. To this end, the author's maintenance operations must use the power board detection as the entry point, and routinely check each data indicator as the main means to obtain the relevant reference data for fault analysis, positioning and judgment.
The fault of the machine is: the cold machine is off for more than ten minutes, the heat machine is out of time for a short time, and the sound is intermittently silent when the backlight is off. The author is slightly determined to be a power board failure, but also consider the motherboard at the same time there is a problem, after the initial observation of the motherboard plug line, there is already a bit number 203, model PJ9D, Sk24 diode solder joint, as shown in Figure (A). After the repair welding, the test sound fault has been eliminated, and the motherboard returns to normal.
After detecting the 5v, 13v, Ps-0N, BLU-0N, LD voltage of the power board, no abnormality was found. Only a small capacitor of 10J6KV was found next to the high voltage output transformer, as shown in Figure (A). Suddenly, I was happy for a while, I was about to dismantle it, and welded it to the same one. The test machine failure has not been eliminated. Why? Ask yourself. The natural idea is to continue to trace the high-voltage board. First, check the high-voltage transformer of the high-voltage board, and find that a transformer is internally broken! As shown in Figure (B), due to the urgency of the mind, a high-voltage board (this board is a plurality of transformer bayonet type, the original machine is in-line type) is replaced by the replacement, as shown in Figure (2). This modification, and successfully lit up the backlight, in order to test the stability of the backlight, let the backlight continue to work, to see the aftereffects. At this point, the mood was a little easier, just like the heart, I thought I was done, and I only enjoyed it for more than an hour.

God? Always toss me up! In desperation, the scene of "the mountain is running out of water, only the road is one", the non-folding screen can not be backlit.
The backlight of this machine is CCFL (cold cathode) tube, as shown in Figure (6).
The driving form is a power supply high-voltage integrated type, and a single transformer is superimposed with a plurality of transformer high-voltage output driving type, as shown in (2).
The light board is a plurality of transformer in-line type, as shown in Figure (B).
The lamp is a loop grounded, as shown in Figure (10).
Therefore, the reclamation process begins here:
<1>, remove the TV back cover and remove all the accessories in the machine, as shown in Figure (1~2).
<2>, remove the TV plastic frame, at the same time, remove the four-sided screws of the screen metal frame, and carefully remove the metal frame.
<3>, place the screen body on a vertical object (the slope is appropriate), and carefully remove the liquid crystal screen (the operation reference is basically the same as in Figure 14), and take out the light guide sheet (several pieces of synchronous operation) It can be seen that the backlight tube is seriously deteriorated, and the end cover is seriously baked, as shown in Figure (5).
<4>, prepare the replaced backlight tube and remove the aging tube, as shown in Figure (6).
<5>, remove all the lamp end blocks (12 pieces) and take them out to wear a high-pressure lamp tube lead (the original lamp board is in-line type is now changed to bayonet type), the lead color is six red and six white, and the length is actually It is suitable to take the material, as shown in Figure (7).
<6>, the end of the threaded end seat is reassembled in the original position. The author asks that the wiring direction is positive and negative, that is, one red and one white order, to be welded, as shown in Figure (8).
<7>, the same amount of heat-shrinkable tube and bayonet plug are used for the butt welding. After the welding, the heat-shrinkable tube is heat-treated to make it heat-shrinked to achieve insulation, as shown in Figure (9).
<8> After the above operation, the lamp is replaced and reset (the direction is positive and negative) as shown in Figure (11). Then connect the accessories correctly, power on the test machine, the backlight is successfully illuminated, and its bright effect is comparable to the original, as shown in Figure (12).
<9> After the backlight is turned on normally, then turn off the power, insert the light guide into the screen to reset, and carefully move the LCD screen into the frame. This operation is damaged when the components of the screen are damaged, as shown in Figure (14). .
<10> After the LCD screen is successfully embedded, it is placed on the workbench to reset the metal frame, and the four-sided screws are properly fastened, as shown in Figure (15~16).
<11> After the above operations are completed, all the accessories of the machine are connected by a wire, as shown in Figure (17). And close the back cover of the machine to tighten the screw, power on the test machine 0K, as shown in Figure (18). At this point, the operation process of replacing the backlight tube of the entire TV set is completed, and the perfect repair success fee is US$203.

Afterword: This case is a comprehensive fault of LCD TV sets. It is also the origin of the "senior syndrome" described in "Preface". The author deliberately uses the analogy method, through the combination of image matching and text description. The reader has a clear direction and deep understanding of the "check", "judgment" and "repair" of the fault, and then, the fault is handled faster and better. The author has been carefully organized and representative. However, whether it is refined or not, of course, the moderator has his own judgment.
Perhaps, some friends believe that: this post is too long, too much." I am sorry, because the author is limited, this is the author's helplessness, the author completely accepts your criticism, because your criticism today is my tomorrow Progress, the author does not do anything to do the best, but to do better. The author is willing to work with the masters and friends as an active forum to enhance understanding, share, share, and improve together.
This post is the author's personal maintenance experience. It is purely an opinion and operation method of personal behavior and does not represent any position. "Strong Request": The author is not familiar with the operation of the computer, and the poster is used to the mobile phone. Here, the moderator is requested to re-edit the paragraphs of the "Preface", "Case" and "Language" of this post, so that the reader can Easy to read, after completing the editing operation, the "Request" section is given to delete the forum space. Here, I would like to express my sincere gratitude to all the moderators for their hard work!