50 inch Rca led problem

[Yosemetesam]

I have a 50lbrq45 I have torn it down completley.
First symptoms red standby light would change to blue no audio or video wouldn't turn off. After tearing it down checking voltages everywhere I baked the main board at 400 degrees for 9 mins. The did the flashlight test and found I had picture and audio but no backlight. One thing I noticed is I could turn the set off after I baked the board. I am not 100 percent baking the board did anything and maybe I turned off before the usual shutdown occurs. I only have pic and sound when I unplug the wire lead for the led,s otherwise they all flash and the unit shuts down. I individually plugged in each light strip and two seem to flash brighter then two others. I am at a dead end

[awyatt2]

Re: 50 inch Rca led problem

something amiss in the inverter or bad led string.

[Yosemetesam]

Re: 50 inch Rca led problem

I tried each led strip separately wouldn't that mean they are all bad? And the other end of the led harness comes out of the power board does that mean the power and inverter are on the same board? I am not real tech savvy please excuse stupid questions.

Thanks

[budm]

Re: 50 inch Rca led problem

Remove the female LED connector from the board, then check each pin of the LED female connector against the chassis to see if any one of them show resistance reading.

[Yosemetesam]

Re: 50 inch Rca led problem

I pulled the harness from the board. Black prone to chassis red probe on all led wires at 200 ohms. I had a constant 1 across the harness no change on each pin. I did that to the male pins on the led light manifold . Using the wire harness is better idea

[Yosemetesam]

Re: 50 inch Rca led problem

Does no resistance mean open circuit or bad connection?

[budm]

Re: 50 inch Rca led problem

open circuit means the wires to the LEDs inside the TV are not shorted to the chassis and cause the board to shutdown, but you may have some LEDs that are shorted out and cause over current for the rest of the LEDs light up brightly and then it goes into over current shutdown mode.

[lookimback]

Re: 50 inch Rca led problem

I had one of these a few months ago with 2 bad LEDs on one strip. They were shorted (not open) and I found the problem by unplugging the dim wire from the power supply, which then made the backlights turn on (not sure if it was the same version as yours, so I don't know if that will work on yours), and then measuring the current each strip was drawing. The current on the bad strip was almost double what the rest were.

[Yosemetesam]

Re: 50 inch Rca led problem

So can I jumper from the main board to the bl on pin to bypass adjust pin which I think is dimmer. Also i unplugged all the led strips and individually tried each strip and same shutdown. I don't believe I had a short in all 4 strips. Woudnt it point upstream to the culprit ( I don't know jack about electronics but all 4?could it be main board or p supply ? But why does all work if take the backlight out of circuit?). I wish the problem was bad caps I would have had this fixed a month ago ��

[lookimback]

Re: 50 inch Rca led problem

Just disconnect adj and see what happens. As for disconnecting individual led strips, it won't work like that. The LED drive controller is going to shut down for undercurrent and overcurrent. So, when it detects that no current is being drawn (because a strip is unplugged) it immediately shuts down. Pictures of your boards would help since we don't know which version you have.

[Yosemetesam]

Re: 50 inch Rca led problem

Not sure where adj is?.

Here is p supply

[Yosemetesam]

Re: 50 inch Rca led problem

You guys rock looks like I need a light strip.

[Yosemetesam]

Re: 50 inch Rca led problem

Do order this exact number? Also any way to trouble shoot lights or better to just replace. Thanks

[lookimback]

Re: 50 inch Rca led problem

Not sure where adj is?.

Here is p supply

That's the one I had. The 3 wire harness on the lower right. Pull the center wire out and the backlight should power on.

[lookimback]

Re: 50 inch Rca led problem

Remove the white reflective sheet so you can get to the strips. The ones which usually fail are where strip doesn't make contact with the metal. You can test them with a multimeter set to diode test mode.

[Yosemetesam]

Re: 50 inch Rca led problem

Got it . You rock