I encountered a Samsung LCD monitor that wouldn't display anything after booting up. The screen was completely black, so I decided to open the unit and inspect the high-voltage board's four-lamp interface.
Using an oscilloscope, I checked the feedback terminals of the two lamp sockets at the bottom of the board and compared their waveforms. Both signals looked identical, which initially suggested there wasn’t a problem with the circuitry itself.
After replacing the upper connector, only one of the feedback signals became normal, while the other remained unstable. This indicated that there was an issue with that particular lamp tube.
The customer needed the monitor to work as soon as possible, so I opted for a temporary repair solution. I connected a capacitor labeled "3KV27J" to the high-voltage port and plugged in the remaining three lamps. The screen turned on, but it still flickered black. When I measured the feedback signal again with the oscilloscope, the two waveforms were still unbalanced.
To fix this, I added another identical capacitor in parallel. This time, the screen no longer went black. Unfortunately, I didn’t get a chance to check the waveform after the machine was fully operational.
During installation, I had to flip the circuit board, so both capacitors were placed at the bottom.
This method can also be applied to LED displays. In my opinion, as long as the peak amplitude of the feedback signal is consistent, even using a simple conductor like a stick could work. It all depends on how well the signal is balanced.
ELCB is an acronym for Earth leakage circuit breaker, which is a device placed inside a water heater, commonly referred to as ELCB electric leakage breaker. This circuit breaker has the function of disconnecting the device from the circuit whenever an electrical leak occurs through the human body when touching the electrical parts of the device.
ELCB is to limit the incident of electric shock inside the machine, disconnecting the power when there is a problem, ensuring safety for human life as well as fire and explosion prevention.
How many types of ELCB?
ELCB is often used in both civil and industrial applications.
For the domestic electricity system, the installation problem is not difficult, but in industry, the anti-shock for workers and the prevention of electrical leakage for electrical equipment with large capacity requires a bridge. Automatic anti-shock, high-power leakage protection, and often has a much higher price.
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