2011 rca 46la55r120q led tv - backlight works, no picture, no sound

[kburks1230]

Need some help with this one. I fired it up and the backlight comes on but I don't get any picture or menu. I don't hear any sounds either. I tested the fuse on the tcon board and it appears to be good. Any ideas?

Thanks!

Ken

[tom66]

Re: 2011 rca 46la55r120q led tv - backlight works, no picture, no sound

What voltage do you read at each end of t-con fuse?

[kburks1230]

Re: 2011 rca 46la55r120q led tv - backlight works, no picture, no sound

I'll read the voltage and export back. I just tested for continuity to see if it was open.

[kburks1230]

Re: 2011 rca 46la55r120q led tv - backlight works, no picture, no sound

.22v at the fuse on the tcon board.

[budm]

Re: 2011 rca 46la55r120q led tv - backlight works, no picture, no sound

The main board is not sending the voltage to the T-CON, there should be a switched MOSFET on the main board close to the LVDS connector that is turn on and supplies the voltage to the T-CON.

[kburks1230]

Re: 2011 rca 46la55r120q led tv - backlight works, no picture, no sound

Do you see the MOSFET in this picture? How do I test it? Or do I just replace it...?

[tom66]

Re: 2011 rca 46la55r120q led tv - backlight works, no picture, no sound

Little 8 pin device near the connector, do you see a part # on it?

[kburks1230]

Re: 2011 rca 46la55r120q led tv - backlight works, no picture, no sound

25l3206e
m2i-12g

[kburks1230]

Re: 2011 rca 46la55r120q led tv - backlight works, no picture, no sound

25l3206e
m2i-12g

[tom66]

Re: 2011 rca 46la55r120q led tv - backlight works, no picture, no sound

Hmm, unfortunately not a MOSFET, but a memory for the processor.

[kburks1230]

Re: 2011 rca 46la55r120q led tv - backlight works, no picture, no sound

There is another board that goes from the main board to the tcon. See the pic attached here.

[tom66]

Re: 2011 rca 46la55r120q led tv - backlight works, no picture, no sound

That is Motion FRC (="frame rate converter") board for 120Hz/240Hz picture. At the top right 4 pin connector what voltages do you get?

[kburks1230]

Re: 2011 rca 46la55r120q led tv - backlight works, no picture, no sound

There is also a bm1084 on the PL MS6M20S 2B board from the last post along with two little 8 pin MP1482DN chips.

The first board I posted a pic of is the the main board with the inputs. The LVDS cable goes from that board to the second smaller board I posted a pic of in my last post. Which is the main board?

[tom66]

Re: 2011 rca 46la55r120q led tv - backlight works, no picture, no sound

Main board has video inputs like HDMI. Above post has motion FRC and there is also a t-con board

[kburks1230]

Re: 2011 rca 46la55r120q led tv - backlight works, no picture, no sound

Tom,

I measure 12v 12v 0v 0v on at that 4-pin connector.

That is Motion FRC (="frame rate converter") board for 120Hz/240Hz picture. At the top right 4 pin connector what voltages do you get?

[tom66]

Re: 2011 rca 46la55r120q led tv - backlight works, no picture, no sound

OK, and on the last right 4 red wires going off to the t-con board (coming out from the bottom of that image) do you read 12V?

[kburks1230]

Re: 2011 rca 46la55r120q led tv - backlight works, no picture, no sound

Nothing on the bottom 4 red wires. The bottom right harness comes from the main board. The left harness goes up to the TCON. I have no voltage on those 4 red wires coming from the main board. I tested those 4 red wires on the main board and have no voltage there as well.

OK, and on the last right 4 red wires going off to the t-con board (coming out from the bottom of that image) do you read 12V?

[tom66]

Re: 2011 rca 46la55r120q led tv - backlight works, no picture, no sound

Hmm, yeah, I looked closely at that board again and the power for the t-con passes straight through the board. Not sure what else to suggest; looks like your main board is bad.

[kburks1230]

Re: 2011 rca 46la55r120q led tv - backlight works, no picture, no sound

Is it worth trying to reflow the main board or is this going to be a bad MOSFET somewhere?

[kburks1230]

Re: 2011 rca 46la55r120q led tv - backlight works, no picture, no sound

Are these two bards interchangeable?

http://******/18AfYp
http://******/18Ag9kO

Same main board number but one is a smaller TV