TOSHIBA LCD TV 50L2300U power-on flashing off the fault repair example - Appliances

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SMD aluminum electrolytic capacitor

Today, I worked on a 50-inch TOSHIBA LED TV model: 50L2300U. The customer brought it in this morning, and upon powering it on, it would flash off after about one second. This kind of issue is quite common in LCD TVs, regardless of the size. From my experience, there are several possible causes for such a failure:

• Power board or constant current board (about 50% chance of being the cause)
• LED strings or lamp beads (around 40% probability)
• Mainboard issues (approximately 8%)
• Other less common reasons (about 2%)

These percentages are based on my personal observations and do not represent any official position. In this case, I focused first on the power and constant current boards because of the quick failure symptom, which aligns with my troubleshooting approach.

After removing the back cover, I noticed that one of the rectifiers on the constant current board had a reversed resistance close to the forward resistance value of a HER303 diode. I replaced it with a new one of the same model, and the TV worked perfectly after testing. The repair cost was $228.