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LG TV model CP-20j52a does not turn on

lilisbet
hace 5 años
hace 5 años
Good, I have a LG TV model CP-20j52a that does not turn on. Once connected to the AC outlet, it enters Stand By but never turns on when I press the power switch, nor does it respond when I touch a volume, menu, TV / AV button. I started measuring the voltages at the source and the 112V of + B are present. In the microprocessor are the 5V of VCC. The 26V of the Vertical power supply that comes out of the flyback does not have them, replace the vertical amplifier with a new one and the problem continues, then I checked the diodes and other components of that circuit and found no more faulty ones. Of course I appreciate all the help you can give me, I don't know what is causing the TV to not turn on and I'm a bit without ideas anymore. regards
luis tartaglia
hace 5 años

Hi. I commented that chassis is thus to guide me to help you.
If the horizontal does not oscillate, it will not have flyback output voltages such as vertical.
You must control the power to the driver transformer. In ST mode and when it gives PW. Placing the tester in st and do not remove it and from PW.
Check if the + b is reaching the TSH manifold, but in st.
Check jungle tension Hvcc. For the doubts in ST and when giving PW. The same in the Hout pin which is where the pulse comes from at the base of the hirizontal driver transistor. You must have the tension in your collector in ST. When I comment chassis it will be more

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luis tartaglia
hace 5 años

Specific. Check the buttons that work well. Pressing should dial 0. PW is given with that of the channel. NO of the volume or menu. These must be powered with 5v. PW with remote control. Do not touch anything else on the vertical cinculto.

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lilisbet
hace 5 años

Thank you very much for the suggestions, it's too late, tomorrow I try and comment on the results.

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lilisbet
hace 5 años

The chassis I think is MC-83C 6870VM0212G I will check your suggestions and tell you

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Javier Chavez C
hace 5 años

Is the MC-83C series printed on the main card?
Please make sure the Chassis so you can be sure and give accurate information.
By saying "I think" we all remain in doubt

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lilisbet
hace 5 años

If the series is printed on the main card

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Javier Chavez C
hace 5 años

Thank you, there I leave the diagram in the comments of my solution proposal

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Javier Chavez C
hace 5 años
hace 5 años
Diagram here: https://elektrotanya.com/lg_cp-14,20j52a,f62a,b86a_chassis_sc-023a_sm.pdf/download.html What voltage do you get in + B both in STBY and on the ON order? What voltage do you get in the collector of the horizontal DRIVER transistor in both STAND BY and ON?
lilisbet
hace 5 años

I do not have a TV remote control. Both in ST and when pressing PW the values are the same, yes the + b is reaching the TSH collector, in the jungle Hvcc is 0v and Hout 0v.

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Javier Chavez C
hace 5 años

Excuse me, the suggestion is not to measure in the TSH, but in the collector of the horizontal DRIVER transistor.

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Javier Chavez C
hace 5 años

Test directly on the Power pin of the microprocessor, if there are changes of Voltages in both STAND BY and the ON order.
Heat the chips or pins on the Microprocessor's swing glass and repeat the test

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lilisbet
hace 5 años

I heated the legs of the microprocessor's oscillation crystal, repeated the test and everything continued the same. I measured the voltage in the collector of the horizontal driver transistor and it gives me 13V. When I press power everything stays the same in ST because it is like the TV does not recognize that it is being sent to turn on.

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Javier Chavez C
hace 5 años

The working conditions of the microprocessor are
Microprocessor and EEPROM voltage.
RESET voltage
Voltage on the microprocessor crystal pins and the good condition of the crystal.
Check the good condition of the command buttons on the front panel. And the power (voltage) of them

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lilisbet
hace 5 años

Thank you very much for spending time trying to help me, in the end I didn't know how to fix the TV and I gave it back to the owner. I think the problem was in the microprocessor, but I didn't have any available to replace it. Really, thank you very much for the suggestions.

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