Greetings friends, I have the following fault on this LG TV Model RP-20CA10. The screen goes black but it has audio. When I start to turn on the TV if the perfect image comes out and also the sound but at the minute the screen turns black but the sound keeps running, it has high voltage and the tube is still on. Sometimes the image appears again well but it comes back to put black and sometimes it is not good again and I turn it off. This TV uses the jungle TB1238BN, Horizontal D2499, regulator STR6654.I have reviewed all the capacitors with the capachek (I measured the capacitors without removing them from the card) and they seem to be OK, I have checked the diodes that are close to the Flyback and have no leak . Also check most of the resistances that are near the part of the flyback where it says ABL. I also found enough weldings in bad condition in the big card and also in that it is connected to the TRC but I have not found more and it follows the Some colleague can help me with the electronic diagram. I have read in some forums that the fault could be in the ABL or in the brightness part but I do not have the diagram to measure voltages and I do not know which signal or voltage I can have in the ABL and how to measure this voltage with respect to which reference point. I would like to know if anyone has had this fault that can give me an idea where the fault may be to proceed to make measurements or some idea of ​​how to attack this type of fault. Usually I do not repair televisions but from time to time. I usually repair repair telephonic central. In advance I thank you for your wise opinions.

Warm regards friend Johelhidalgo, observing everything you said and done, when the TV is dark you must measure the voltage of ABL in the flyback pin since this voltage reaches this pin through resistors that come from the B + to the pin of the ABL must reach at least from 9 to 12VDC, you must follow this line to ic jungle in the path of that track you will find glass diodes that can be open or short, check the resistances that are in the circuit abl, another possibility can be the screen voltage that is failing, this comes from the flyback and once the base of the screen where it connects the red, white cable coming out of the flyback, it is often this base that sulphates and works half , that I can conclude or deduce since you mention that sometimes works ok and sometimes not, check this data and comment your resusltados to continue your help. regards