Good night. I comment: According to what you say I conclude that the source works perfectly. what happens is that you say that the "Voltages are gone" is that the source works by sending a standby voltage to the main, it is usually 3.3v or 5v that voltage is processed by the main board and when the main detects that these voltages There is a power order sent to the source to enable the rest of the voltages. You should check which is the integrated corresponding to that stage of on / off standby and if the integrated is well you have a problem in the microprocessor. PD: It may be some smd component of the main related to the on / off standby. But I already tell you that from my experience that is unusual on a television under 8 years old.