Toshiba 50L5300UC no power LED

[tech2014]

I have a toshiba lcd tv that has no front power LED. It doesnt turn on, but I get all of my voltages,except the BLON. I get 0v. When the power is turned on the LED stays off and I get nothing on the screen, even with the flashlight test. The customer said the TV will sometimes turn on and work fine, then it will shut down. If its a backlight not turning on, and since the power LED doesnt come on, would that point to a main board issue. I can't find a service manual, I hate working on Toshibas.

There are only 2 boards, a power supply and main board. See pics.

[tech2014]

Re: Toshiba 50L5300UC no power LED

so nobody has a clue? This board hasn't been helpful lately.

[budm]

Re: Toshiba 50L5300UC no power LED

https://www.badcaps.net/forum/attach...1&d=1453777713
Please report the readings of each pin of the J206 when TV is OFF and when TV power switch is activated, YOU MUST put down the pin names of each pin in your readings.

[tech2014]

Re: Toshiba 50L5300UC no power LED

Here are the voltage reading :

Pin 1-3 12V2-12.49V
Pin 6 12VA=12.5V
Pin 10 5V1=5.14V
Pin 11 ACD=3.545V
Pin 12 PWON=3.30V
Pin 13 BLON=0V
Pin 14 5V1=5.14V
Pin 15 DIM=3.23V

[tech2014]

Re: Toshiba 50L5300UC no power LED

I think I found the problem on the main board. There is a power distribution IC U15. I get 12.4V at the VIN pin 1, but my EN and VOUT pins are both at 0V. Part number is APL3546A.

This IC controls the voltage for the BLON transistors.

[tom66]

Re: Toshiba 50L5300UC no power LED

If EN is low, the regulator should be off, so for some reason the main CPU isn't sending the on/off signal.

[tech2014]

Re: Toshiba 50L5300UC no power LED

So it is definitely a main board problem then?

[budm]

Re: Toshiba 50L5300UC no power LED

'Pin 13 BLON=0V' So the main board is not sending the BL-ON signal to turn on the Backlights circuit.
'I get 12.4V at the VIN pin 1, but my EN and VOUT pins are both at 0V. Part number is APL3546A.

This IC controls the voltage for the BLON transistors.' So the processor is not sending the signal to EN pin to turn the IC APL3546A on.
So you need to trace out where that EN pin goes to.

[budm]

Re: Toshiba 50L5300UC no power LED

So it is definitely a main board problem then?

Yes.

[tech2014]

Re: Toshiba 50L5300UC no power LED

Does anyone have any idea where I can find a main board replacement?

[fberni]

Re: Toshiba 50L5300UC no power LED

repair manuals http://www.toms-service-manuals.com/...h=Submit+Query

[skipnich]

Re: Toshiba 50L5300UC no power LED

I'm having the same issues with my TV. All voltages are similar. Did you ever find a source for a replacement board?