RCA 47LA55RS Red Light OK, Not power ON

[alfredomfr1]

5v and 12v ok, no power on, when plug the power cable the relay sound one time first and one-two, one-two after that a weir sound but nothing happen.
Power Board Model: HLP-45D01

[alfredomfr1]

Re: RCA 47LA55RS Red Light OK, Not power ON

There are nothing related to troubleshot this tv power board on the web, any help?

[alfredomfr1]

Re: RCA 47LA55RS Red Light OK, Not power ON

I made a bridge between power-On and stby(5v) and the TV turn on when power button is pressed, the red light led become blue but still no backlight on screen.

Voltage Read:
24v: 25v
12v: 11.69v
14v: 16.79v
5v: 5.26v

Any suggestion?

[CapLeaker]

Re: RCA 47LA55RS Red Light OK, Not power ON

Did you have a look at the inverter board?

[alfredomfr1]

Re: RCA 47LA55RS Red Light OK, Not power ON

This TV has 2 inverter boards, how can I test these 2 boards?

[CapLeaker]

Re: RCA 47LA55RS Red Light OK, Not power ON

Aaah! It has a Master and a Slave backlight setup. Does the backlight come on for 2 secs and off or no backlight coming on at all? You can check if the main board is actually giving the turn on signal to the backlight. I can't see the pinouts on the power supply. Basically there are some wires going from the power supply to the inverter board. Turn the TV on, and check the BLON pin on the power supply. You also should check fuses on the inverter board. Maybe some pics of the inverter boards would be nice.

[alfredomfr1]

Re: RCA 47LA55RS Red Light OK, Not power ON

In the backlight connector (Pic 3) which is the BLON pin?

[Moreno83]

Re: RCA 47LA55RS Red Light OK, Not power ON

I would try and replace those 2 caps also
I fixed a samsung lcd with no backlight with replacing those caps!

[alfredomfr1]

Re: RCA 47LA55RS Red Light OK, Not power ON

Master
24V: 25v
BRI1: 1.66v
SW1: 4.97v
BRI2: 0v
SW2: 0v

[alfredomfr1]

Re: RCA 47LA55RS Red Light OK, Not power ON

I have not 680uf 35v capacitors, I need to order.

[Moreno83]

Re: RCA 47LA55RS Red Light OK, Not power ON

Do you have other capacitors?
For example 4x 330uf?

[alfredomfr1]

Re: RCA 47LA55RS Red Light OK, Not power ON

560uf 25v, nothing close to 35v

[CapLeaker]

Re: RCA 47LA55RS Red Light OK, Not power ON

And the measurements on the Slave? Looks like the Master is getting juice from the power supply. Does the backlight attempt to turn on for a second or nothing at all?

[alfredomfr1]

Re: RCA 47LA55RS Red Light OK, Not power ON

Slave
24v: 25v
BRI1: 4.97
SW1: 1.66
backlight did not attempt to turn on.

[budm]

Re: RCA 47LA55RS Red Light OK, Not power ON

https://www.badcaps.net/forum/attach...1&d=1422285528
What DCV do you have on CN1? Especially the pin 12_ON/OFF.
Please post all the readings of the CN1 connector.

[alfredomfr1]

Re: RCA 47LA55RS Red Light OK, Not power ON

CN1
24V: 25.05v
VBR-A: 1.66v
on/off: 4.97v
VBR-B: 0v
Status: 0v

[budm]

Re: RCA 47LA55RS Red Light OK, Not power ON

OK, the control signals and the 24VDC are OK.
I see that there is small white ribbon cable with 4 pins, does it go to the T-CON board? If it does go to the T-CON board, remove it and see what happen.

[alfredomfr1]

Re: RCA 47LA55RS Red Light OK, Not power ON

ribbon cable removed, backlight come on for a second and turn off

[alfredomfr1]

Re: RCA 47LA55RS Red Light OK, Not power ON

How can I test the inverter board in order to determine the defective one?

[alfredomfr1]

Re: RCA 47LA55RS Red Light OK, Not power ON

Any help?