Greetings to all, I hope you are well.
I consult you because I have a problem with this power source.
The TV when it is connected to the electrical power turns on the blue light but does not give an image. the source is heard a hum.
When I disconnect the power from the TV plates and power it up by itself, the hum goes away.
I have the STB voltages of 5vdc. The microcontroller is powered with said voltage and the main board LED lights up.
but not the 12v or 17v ones, nor the 300vdc high voltage voltages, nor the VS or VA.
I checked about 60% of the components of said source, I measured the ESR of the electrolytic capacitors, they are fine, then when in doubt, I removed them all and measured their capacity and they are correct.
I took out all the octocouplers and tried them one by one, they are all good.
From the PFC source I took out the rectifier diode and the mosfets and the medi, they are good.
From the high source, I measured the mosfets and they are good, a colleague told me that it was a problem with the IC801 L6599D, oscillator. I bought the replacement and installed it, but nothing. the font doesn't work.
According to the LG TV (Plasma) service manual, when connected to the 110vac line, this source is fully activated, delivering all voltages.
But when you do that, you only hear the activation sound of the relays for less than 1 sec and they disconnect and you hear a loud sound like a buzzer but you obviously don't have one installed.
The PFC capacitors (C621, C625, C626) are charged by line voltage but then start to drop to line voltage until they are discharged. In capacitor C160 it is maintained at 160vdc
The voltage on IC801 L6599D VCC rises to 11.2vdc and drops immediately, in another sector I found a stable 24vdc.
I did not find the diagram of this source, I do not understand who drives the relays or who goes to work first, the PFC or the other oscillator.
Who can give me a guide what else to review? Some schematics from a similar source.
Thank you very much to all.
I consult you because I have a problem with this power source.
The TV when it is connected to the electrical power turns on the blue light but does not give an image. the source is heard a hum.
When I disconnect the power from the TV plates and power it up by itself, the hum goes away.
I have the STB voltages of 5vdc. The microcontroller is powered with said voltage and the main board LED lights up.
but not the 12v or 17v ones, nor the 300vdc high voltage voltages, nor the VS or VA.
I checked about 60% of the components of said source, I measured the ESR of the electrolytic capacitors, they are fine, then when in doubt, I removed them all and measured their capacity and they are correct.
I took out all the octocouplers and tried them one by one, they are all good.
From the PFC source I took out the rectifier diode and the mosfets and the medi, they are good.
From the high source, I measured the mosfets and they are good, a colleague told me that it was a problem with the IC801 L6599D, oscillator. I bought the replacement and installed it, but nothing. the font doesn't work.
According to the LG TV (Plasma) service manual, when connected to the 110vac line, this source is fully activated, delivering all voltages.
But when you do that, you only hear the activation sound of the relays for less than 1 sec and they disconnect and you hear a loud sound like a buzzer but you obviously don't have one installed.
The PFC capacitors (C621, C625, C626) are charged by line voltage but then start to drop to line voltage until they are discharged. In capacitor C160 it is maintained at 160vdc
The voltage on IC801 L6599D VCC rises to 11.2vdc and drops immediately, in another sector I found a stable 24vdc.
I did not find the diagram of this source, I do not understand who drives the relays or who goes to work first, the PFC or the other oscillator.
Who can give me a guide what else to review? Some schematics from a similar source.
Thank you very much to all.
Attached Files
