Hisense plasma TPW5029D AV2 picture flash, black screen - appliance repair - Database & Sql Blog Articles

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Model: Hisense TPW5029D
Movement: Plasma-MST6
Fault Phenomenon: AV2 picture flickers and eventually turns black, while the sound remains normal.
Diagnosis and Repair: After powering on, the AV1 input signal was normal, and the image displayed correctly when AV1 was connected. However, when switching to AV2, the image became distorted and unstable, eventually leading to a black screen. The audio remained unaffected throughout.
Analysis: Since AV1 worked properly, the issue wasn't related to the signal processing or channel circuits in the later stages. Therefore, the problem likely originated from the AV2 input or the signal switching section. However, since the signal initially displayed normally, it ruled out a faulty switching circuit. Upon closer inspection, it was noticed that the image brightness increased before turning black, suggesting an impedance mismatch at the AV2 input.
Solution: Further testing revealed that the matching resistor R210 at the signal input had unstable resistance, fluctuating between infinity and hundreds of ohms. Replacing the resistor resolved the issue. The root cause was traced back to frequent plugging and unplugging of the AV cables, which caused wear and intermittent contact over time.