Philips 32PFL1335/98, no backlight

[anton74]

Hello,

I am trying to repair the backlight problem in my Philips 32" TV. I don't have a backlight tester but I checked all the LEDs with the multimeter - all of them are OK. The voltage at the output of the driver IC (OB3362VP) is about 12V. I tried to measure this voltage when turning on the TV and did not see anything higher than 12-14V. Does it mean that the driver IC is defected and need to be replaced? Could it enter the protection mode if the connections between the individual LEDs are bad? Of course, I will try to power the LED strips from the lab power supply, in order to exclde the issue with the LED strips.
Thanks!

[CapLeaker]

Re: Philips 32PFL1335/98, no backlight

Only because you tested the LEDs in diode mode with your DMM, doesn’t mean the LEDs are good. You’d have to put some power to them and see what happens, in order to totally rule the LEDs being a problem. Plug the back lights back into the PSU and measure the voltages on each voltage string. When you turn the TV on, the voltage should ramp up fast and then ramp down again. You could have an open string too.

[anton74]

Re: Philips 32PFL1335/98, no backlight

I tested the strips with the laboratory power supply today. Al LEDs are OK. There is no high voltage upon turning on the TV. The output of the driver is almost steady 12-14V.

[yokoono]

Re: Philips 32PFL1335/98, no backlight

If the LEDs are ok:
1. BL ON and DIM command missing
2. Defective controller (driver)
3. Defective mosfet.

[anton74]

Re: Philips 32PFL1335/98, no backlight

I will check the MOSFET and the presence of ON and DIM signals. Thanks!