Sony KDL-49WE663 red led blinks 6 times

[heol]

Hi.

I'm working on a Sony KDL-49WE663 and when I first turned it on it was blinking red 6 times.
I opened the TV and saw an inductor was fallen off the power/LED driver board so I soldered it back on and tested again, TV turns on and seems fine but the inductor heats up really fast and fell off again.

Then tested the backlight LEDs they all seem fine with LED backlight tester, every LED lights up. I even measured current draw to all individual LED which was around 27 mA.
Haven't found any shorts after hours of testing.
Inductor is about 4.5 Ohms.

Wondering if someone has experience with these TVs? Any pointers where to look?

Attached the picture of the powerboard and diagram from datasheet of driver IC since I cannot find schematic for this TV. The inductor is marked with red.

[dick_barton]

Re: Sony KDL-49WE663 red led blinks 6 times

What voltage do you have on Pin 1 (VCC) and Pin 3 (Reg9V) of the Led driver IC?
Interesting that the inductor fell off. Have you checked that the mosfet is not short circuit?

[heol]

Re: Sony KDL-49WE663 red led blinks 6 times

VCC pin 1 is 18.8V
Reg9V pin 3 is 8.9V

Mosfet is not shorted.

[dick_barton]

Re: Sony KDL-49WE663 red led blinks 6 times

Those voltages appear to good so it doesn't look like the driver IC is faulty.

[dick_barton]

Re: Sony KDL-49WE663 red led blinks 6 times

Have you checked the diode. The photo is small so hard to work out what goes where. Are there components on the underside?

[heol]

Re: Sony KDL-49WE663 red led blinks 6 times

Diode that is shown near the gate of the mosfet is not in this PCB instead there is 1 resistor which measured ok 68 Ohm.

The schottky diode measures ok.

Zener diodes also ok at least no short.

The inductor gets very hot. There must be a short somewhere but I would think there would be other components also get hot they are shorted but cannot find any.

Underside does not have any components.

[dick_barton]

Re: Sony KDL-49WE663 red led blinks 6 times

Can you measure the resistance of each of the led IC pins to chassis and see if there is a short circuit on any of them?

[SLK001]

Re: Sony KDL-49WE663 red led blinks 6 times

Inductor is about 4.5 Ohms.

I think you found your problem.

[heol]

Re: Sony KDL-49WE663 red led blinks 6 times

No short at the pins to chassis.

I think you found your problem.

I will try and replace the inductor. But I measured it again it was near 1 Ohm.

[SLK001]

Re: Sony KDL-49WE663 red led blinks 6 times

I will try and replace the inductor. But I measured it again it was near 1 Ohm.

It should be in the range of sub 100 milliohms.

[alfatv]

Re: Sony KDL-49WE663 red led blinks 6 times

Inductor can get hot if there are shorts in windings.

[dick_barton]

Re: Sony KDL-49WE663 red led blinks 6 times

Someone else recently had a backlight failure due to a faulty inductor. It looks as this may become a more common problem.

[heol]

Re: Sony KDL-49WE663 red led blinks 6 times

Would you think it would make any difference if this 22uH inductor is replaced with 33uH for testing?
Just something I have laying around.

[Pingas]

Re: Sony KDL-49WE663 red led blinks 6 times

hello, try to open the tv and test all the individual low voltage leds and see if they all have the same current consumption

[mostafa221]

Re: Sony KDL-49WE663 red led blinks 6 times

Hello Heo.
Did you solved the problem?
I have the same problem in my tv the same model. the coil 22uh got very hot and other coil in the main board as well near to the vlds cable coming back to powersupply.
plz tell us if u solve it.