I recently worked on a Konka LCD TV model LC24FS66DC, with motherboard number 35015272. The main issue was that the buttons were unresponsive, and sometimes the TV would turn on but immediately go into standby mode with the message: "You have entered the standby state, don't forget to turn off the power," then shut down. It was really confusing — was it just me being sleepy or was the TV actually entering standby? I'm not sure if Konka's wording is correct here, but it definitely needs improvement.
After disassembling the unit, I checked the voltage on the button board and found it to be normal. All the button resistances were within range, and using the X10K setting on my multimeter, I confirmed there was no leakage. The buttons looked new, with no signs of rust or damage. The input voltage at the socket was 3.3V, so I ruled out the buttons as the problem.
Next, I measured the main board voltages: 12V and STB3.3V (which read 3.4V). The reset circuit output was also normal, showing a high-level pulse when powered on. However, when checking the voltage at pin 130 of the MCU, I found it to be 0V. That was a major clue pointing toward a possible open circuit in the circuit.
Looking at the schematic, I suspected R561 (a 100Ω resistor) might be open. There was a lot of gray glue around the XS644 socket, so I carefully removed it. After some time, I finally revealed R561, which had been hidden under the adhesive for years. Measuring its resistance showed infinity, meaning it was indeed open. The trace from R561 to the MCU pin 130 was intact, so replacing the resistor fixed the issue.
Attached are the schematics: Konka 35015272.pdf
Another repair involved a Changhong LT4024 TV. It would power on and enter standby, but the screen wouldn’t light up. I measured the 24V power supply, and it spiked briefly before dropping to zero. The start signal was normal, but the optocoupler (pin 1 and 2) had no voltage to ground, indicating a loss of power supply. After removing the white glue around the optocoupler, I found R863 open, which was the root cause.
I also repaired two plasma TVs where the X-plate chip resistors had opened, causing black screens or vertical lines. In both cases, the faulty resistors were covered in glue. This made me wonder — is this a coincidence, or does the glue affect heat dissipation, thermal expansion, or mechanical stress over time?
After all these repairs, I feel like the most frustrating part isn’t the technical challenge, but the unclear messages from the TV itself. I think Konka should change the message from "You have entered the standby state" to "Your TV has entered the standby state." It sounds more natural and less confusing.
These kinds of repairs take time, patience, and attention to detail. But seeing the TV work again after fixing the issue is always satisfying.
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