Konka LCD TV LC24FS66DC button is not easy to use - are "glue" to blame - appliance repair
Konka LCD TV LC24FS66DC, motherboard 35015272. Symptom: The button is not easy to use, and occasionally it can be turned on but immediately "you have entered the standby state, don't forget to turn off the power", and then shut down. First spit a slot, but also you have entered the standby state, I am snoring or am I asleep? It is the TV enters the standby state! ! ! Konka’s wording is not right here, huh, huh, don’t be true with him, or study TV! Rice cooker relay is a common device in the automatic control system. It is generally used to connect and disconnect the circuit. It is an important part of the automatic control and remote control circuit. Rice Cooker Relay,Rice Cooker Electromagnetic Relay,4-Pin Rice Cooker Relay,Rice Cooker General Purpose Relay Ningbo Xingchuangzhi Electric Appliance Co.,Ltd. , https://www.xingchuangzhi.com
Disassemble, measure the voltage of the button board is normal, the resistance value of each button is normal, the pointer table X10K file measures the keys without leakage, the appearance is newer and no rust, the voltage of the button input terminal at the socket is 3.3V, which determines that it is not a button problem. .
The main board 12V, STB3.3V (actual 3.4V) is measured. The reset circuit output is normal (high-level pulse at power-on). In turn, measuring the voltage of the MCU 130 pin 0V, found a major clue.
From the drawing, it should be R561 (100Ω) open circuit or line break, where is R561? There is a lot of gray glue on the socket XS644, the glue is carefully removed, and the R561 buried for many years is finally revealed. Measure the resistance of R561 to infinity, R561 to MCU 130 pin line is normal, replace R561 troubleshooting.
Attach the drawings: Konka 35015272.pdf
Changhong LT4024, open/standby response but the screen is not bright, measuring power supply 24V output voltage rises immediately after the moment it will go to 0, the measurement start signal is normal, 24V voltage regulator optocoupler 1, 2 to ground without voltage, obviously optocoupler Loss of power supply causes instantaneous protection of the power supply. A pile of white glue around the optocoupler is removed and exposed to R863. The measurement has been opened.
L32F2350B backlight constant current plate sampling resistor open circuit leads to black screen
In the past two years, I have also repaired two plasma X-plate chip resistors to open the screen and display vertical bars. The common point of these faults is that there are glues on the bad resistors! !
I am afraid it is no coincidence! What do you think? Is it affecting heat dissipation, thermal expansion and contraction, or what is "stress"?
Finally finished, I think again, Konka, please change "you have entered the standby state" to "your TV has entered the standby state"