Ok so the BL turns on the backlight while PS-ON turns on the auxiliary power supplies. Following the circuit it seems to have understood that the two transistors QM853 and QM855 OR the presence of the two signals: presence of backlight voltage and PS_ON. Maybe that's why the TV still works even without PS_ON connected. I would like to understand why the PS_ON signal is knocked down to GND when connected. The fault could fall on the two transistors but I can't figure out what type of components they are. By measuring them they would seem like MOS but even in this case the behavior is very stra...

The BLU_ON signal rises to 5V when the TV is on and drops to GND when it is off. So is that the signal that controls the power supplies? I was convinced it was PS_ON....
I'd like to understand what PS_ON is for and find the fault that leads to the behavior I described. I don't think I can trust myself to leave it unplugged...​

This is the situation:
With ps_on connected:
This signal (PS_ON) does not move and remains at 0V both by operating the remote control TV and from the key.
Tensions on the exit of the Switching power supply are present and stable while on the connector there is only A5V, but not present B5V and not even Vamp and B13V.

If you disconnect PS_ON, operating from remote control or button, the tensions on the connector are correct and the backlight lights up and turns off correctly. A correction compared to what has been said before: With PS_ON disconnected, the 5V voltage...

Hi everyone,
I just repaired one of these power supplies, classic breakdown of str6052s and cm804 (snubber cap).
Now all the power supplies are OK but I have strange behavior on the TV, once I turned it off using the remote control it never turned back on even though the power supply is still OK. I did several tests and came to the conclusion that by disconnecting the PS_ON conductor, the TV turns on and off correctly. Strange! The PS_ON signal coming from the main board emits a 5V signal for a few seconds when turned on and then returns to 0V (if disconnected from the power supply)...