Changhong color TV PF2139 one machine diseased fault repair - Home Appliances

Single chip microcomputer STM32L151CCU6

Brand AVX TPSE226M035R0125 Low impedance tantalum capacitor AVX 22

Electronic scale crystal oscillator 3.2*2.5mm 3225 16M (16.000MHZ) 12PF 10PPM 20PPM 30PPM

This morning, someone brought a Changhong 21-inch color TV PF2139, which was repaired in another store nearby. The original fault was not turned on. The master said that the high voltage package was broken. After switching the high voltage package, it could be turned on, but the image is not. Normal, the master repaired for two days and said that it was not repaired. He could only change the motherboard. The user did not agree to get me here. Plug-in check, it can really start, the fault is that the center of the line deviates to the right by about 10 cm, there are several horizontal lines at the top of the image, and sometimes the image is still beating. Quote 80, the user agrees to repair. Disassemble the machine and check the new high-voltage package. Many parts of the field have also been changed. The large pieces also have signs of welding. There are other suspected solder joints in the repair welding block, and the boot failure remains. First, do not worry about changing things, first measure the field block voltage, then the field block is TDA8356, find the 6th pin voltage 16V, the normal should be 45V, look forward to the vine, find the high voltage package rectification output 45V normal, to 6 feet There is a 10 ohm resistor R404, the measurement has been opened, replaced with a resistor, and the upper retrace line problem is solved. After researching the problem of the center of the line, the line center is not normal. It should be a line pulse problem. After careful observation, the 6-pin copper foil of the high voltage package is broken. The broken position is on the side of the rivet. It is really difficult to detect. After welding, the center is normal. However, the image is somewhat too large, and the high voltage of the high voltage package may be insufficient. The reverse capacitance is appropriately reduced, and the image is completely restored.
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