60-inch Sony repair and improvement - android - Phones Developers

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A week ago, a user went to the store and said that the 60-inch Sony in the house looked at the camera at night and suddenly there was no image. [The old man at home looked at the day and night] At that time, he thought that who shut the TV. Half of the price of Suning, which was bought by more than 4,000 people at the roadside fair, was out of luck for half a year. Now that there are no bills, you can only repair it yourself.
The maintenance door-to-door knows that this Sony TV is fake, although the appearance of the machine is very beautiful. After the power is turned on, the red light turns blue, the backlight of the screen is bright, and there is no gray screen. The test board has only one set of 12V power supply [the power supply does not have a PFC circuit, the switch tube TK5P65W is 60W, no heat sink]. LED power supply has 135v, normal no problem, touch the motherboard, the frequency multiplier board has temperature rise, the test logic board has no 12v voltage, short circuit to ground, VDD, VGH, VGL should have no problem with the ground resistance value, it seems that it can only be IC The boost switch tube or the chip capacitor is faulty. It is found that the VGH switch tube CE junction is short-circuited along the line, but the boost diode has nothing to do, it is not the breakdown caused by the load, the model is silk screen COPA12, check There is no parameter data, only according to the line analysis is the triode [non-field effect tube] C C5706 [5A.50V.15W] substitution, VGH has 34.6v output, a bit high, the phone asks a maintenance screen peer said that there is such a high Voltage board.
Improve the sound of the test machine is normal, after working for a period of time, I feel habitually feel the temperature of the motherboard, the frequency multiplier board, the logic board, and I don’t dare to touch it for a long time. It is estimated to be forty or fifty degrees. [If you install a plastic back cover, It is much higher, because the space of the assembly machine is small, which is not conducive to heat dissipation. The power supply voltage is also no problem. The temperature is definitely the culprits of its early death. It seems that it can only be installed on the multiplier, logic and two power supplies to help it. Cooling [There was no heat sink at all, so I was angry and attacking the heart]. Afterwards, I even drilled two centimeters of holes on the back cover to help convection and heat dissipation. The half-hour cooling effect of the upper cover test machine is very obvious. It seems that this [Sony] finally has a cool office.