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LCD TVs - LED

LG 42LN5700 TV does not turn on

Robert2cs
hace 5 años
hace 5 años
Good Morning, I have an LG 42LN5700 TV that only turns on standby. When you try to turn it on, the standby switches off for two seconds and turns on again but the TV does not turn on or emit sound. Measuring the secondary voltages I only have 3.5V, no 12V or 24V. I made a bridge between those 3.5V and PWRT_ON and there are no voltages either. In the LG service manual there are no further details of this card, they are sent to replace it directly. Has anyone already had a similar fault that can help me?
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wilson sepulveda
hace 5 años

hello when you give power that voltage has in the pin pwr on must return the voltage to activate the source, and how did the yumper between 3.5v and pwr on, if I disconnect the
https://www.google.com/url?client=internal-uds-cse&cx=partner-pub-2856131593189319:3175406767&q=https://www.yoreparo.com/tv/televisores/lcd/led/preguntas/1571988/ lg-42ln5700-sb-titila-el-led-de-stand-by & sa = U & ved = 2ahUKEwjL3dWTmPjiAhVjmeAKHSVxCUgQFjABegQIDhAB & usg = AOvVaw279ZpWg0gDzh5h4T42dYxWudos

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franciscovallarta
hace 5 años
hace 5 años
check the status of fuse 101 if it is open, it will have the mosfet short for fcc operation If the fuse is in good condition check the polarization and operation of the ic oscillator ic 601 I leave the diagram of the source to facilitate its work ... greetings. LG + EAX64905401, + EAY62810601 + LED + PSU.pdf [1.43MB]
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Robert2cs
hace 5 años

Thank you very much, it is not the specific manual, but I found the exact manual is eax64905301.
I saw that I have no voltage on IC202. Checking I found that it feeds on the Q201 mosfet. There I have approximately 30V between Gate and Gnd and 31V between Sourse and GND, if Vgs is 1V or should I turn on and the mosfet could be good?

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Robert2cs
hace 5 años

I've been checking the TV in my spare time, and I found what seems to be the fault. Transistor Q202 (TC3551T) is burned. It has its 3.5V in the base but not active. Would there be any way to place a temporary resistance to prove that it has nothing more damaged?

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Robert2cs
hace 5 años
hace 5 años
Sorry I had not uploaded the manual of the power source, I thought I could not. Today I will look for the transistor if they sell it. Do you know any replacement of that TC3551T transistor? lg_eax64905301_lgp42_13pl1_led_tv_sch.pdf [280.02kb]
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