Changhong rear projection TV CHD4369S repeated burning tube fault repair example - Home Appliances

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

MOS power IC full range

Brand AVX TPSE226M035R0125 Low impedance tantalum capacitor, AVX 22

ESD TVS electrostatic protection tube, 0201 package, 3.3V ultra low capacitance ESD

Inductance

When I tested the Changhong rear projection TV model CHD4369S, I found that the boot check line C5143 was shorted, causing the current limiting resistor to burn out. After powering it on, the screen turned red with a retrace line, and there was no image for three seconds. I checked the tube and it burned again. Since the time was limited, there was no voltage detected. I replaced it, and the main power supply voltage of 125V was normal, but the shutdown was too late, which caused another burnout. It was quite scary. After careful analysis, I noticed that the red screen during boot was present, so I thought the high voltage package wasn’t broken. Then I removed the red gun high voltage line and the red visual release board completely. The boot image and sound were normal, but the red color was slightly reduced. After some time, there was no more burning of the tube. I first measured the red cathode discharge and found no voltage, while 200V was normal. However, the TDA6111Q chip wasn’t receiving the signal. The current limiting resistor had burned out. I replaced it with a 33-ohm resistor and installed the TDA6111Q. After that, everything worked normally during boot.