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

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Inductance

During the repair of a Changhong rear projection TV model CHD4369S, I encountered an issue with the boot-up process. The C5143 capacitor was shorted, causing the current-limiting resistor to burn out. When I powered it on, the screen turned red with a retrace line, but there was no image for three seconds. After checking the tube, it burned again. Due to time constraints, I didn't get any voltage readings. I replaced the component, and the main power supply voltage of 125V was normal, but the shutdown occurred too late, which was quite alarming.

Upon further analysis, the red screen indicated that the high-voltage package wasn’t broken. I decided to remove the red gun high-voltage line and the red CRT board completely. After doing this, the boot-up image sounded normal, though the red color was slightly dim. After a while, the tube didn’t burn again. I then measured the red cathode discharge and found no voltage, but the 200V supply was normal. It appeared that the TDA6111Q wasn’t receiving power due to the burned current-limiting resistor.

I replaced the resistor with a 33-ohm one and reinstalled the TDA6111Q. After that, the TV booted up normally without any issues. This experience taught me the importance of careful inspection and understanding the circuit flow before making replacements. Sometimes, even a small component like a resistor can cause major problems if not addressed properly.