LG 47LN5200_U: PWR, MAIN, and all LEDs replaced, no picture

[JDC]

Re: LG 47LN5200_U: PWR, MAIN, and all LEDs replaced, no picture

At this point we know that we do have the 12V at the fuse to run the board, so it is either bad T-CON or the main board is not sending the signals to the T-CON board. Also what do you get when you only have one ribbon cables between the T-CON and the LCD panel connected one at time, also we also hope that all the cables are properly seated for sure.
So did you have image on the screen before the LEDs backlights went out or not?

The TV was given to me dead with a blown fuse on the power board. Once replaced, the power light would come on and the screen would blink. Once the power board, main board, and LED strips were replaced, the TV would light up and I'd hear snow from the speakers. That's where we're at now.

[budm]

Re: LG 47LN5200_U: PWR, MAIN, and all LEDs replaced, no picture

I don't have those boards handy at the moment. How's your day going?

I measured .2 ohms for the F1 fuse. Does that sound okay?

At this point we know that we do have the 12V at the fuse to run the board, so it is either bad T-CON or the main board is not sending the signals to the T-CON board. Also what do you get when you only have one ribbon cables between the T-CON and the LCD panel connected one at time, also we also hope that all the cables are properly seated for sure.
So did you have image on the screen before the LEDs backlights went out or not?

[JDC]

Re: LG 47LN5200_U: PWR, MAIN, and all LEDs replaced, no picture

I don't have those boards handy at the moment. How's your day going?

I measured .2 ohms for the F1 fuse. Does that sound okay?

[budm]

Re: LG 47LN5200_U: PWR, MAIN, and all LEDs replaced, no picture

So back to square one, we do have Voltage to run the T-CON but you do not get image on the screen.
So to be sure, before the LEDs went out, you were getting the pictures fine then the backlights went out so you start replacing boards but it turns out to be backlights problem, right?
I would put all the original boards back in place and see what happen.

[JDC]

Re: LG 47LN5200_U: PWR, MAIN, and all LEDs replaced, no picture

Post #16 you made the Voltage test and this is what we are told:

F1 fuse on TCON:

ON .014 both sides
OFF 0 both sides

We are chasing tail here.

This is my fault. See attached. That's what I was measuring from. I saw what looked like F1 and assumed that's what you were talking about.

The way I have the TV set up on my workbench, the light casts a shadow over the F1 fuse you have been refering to the entire time. I never saw it. The F1 marking was in the shadow.

[dick_barton]

Re: LG 47LN5200_U: PWR, MAIN, and all LEDs replaced, no picture

I think it's a lot to take in when your unfamiliar with electronics and servicing in general and what we take for granted as being common sense is quite alien to the beginner. Especially terminology. So you try to take it one step at a time and hope that the assistance offered through the Forum does the job.

[budm]

Re: LG 47LN5200_U: PWR, MAIN, and all LEDs replaced, no picture

Post #16 you made the Voltage test and this is what we are told:
https://www.badcaps.net/forum/newrep...reply&p=651873
F1 fuse on TCON:

ON .014 both sides
OFF 0 both sides

We are chasing tail here.
So now you do have 12V feeding the T-CON board.

[JDC]

Re: LG 47LN5200_U: PWR, MAIN, and all LEDs replaced, no picture

That is white component is the SMD fuse which should have 12VDC on it.

Which it does (12.11 VDC); I just checked while the the TV was on.

The problem is that I'm not following the terms you are using correctly. You said the F1 fuse is the only fuse on my TCON? Then you say that the fuse I circled in the pic is a SMD fuse? I don't understand.

[budm]

Re: LG 47LN5200_U: PWR, MAIN, and all LEDs replaced, no picture

Courtesy Shopjimmy

I wonder now as to which FUSE that he tested and got 0VDC reading.

[dick_barton]

Re: LG 47LN5200_U: PWR, MAIN, and all LEDs replaced, no picture

Courtesy Shopjimmy

[budm]

Re: LG 47LN5200_U: PWR, MAIN, and all LEDs replaced, no picture

What is the component that I circled then?

That is white component is the SMD fuse which should have 12VDC on it.
So it that the one you measured the Voltage and you get 0VDC?

[JDC]

Re: LG 47LN5200_U: PWR, MAIN, and all LEDs replaced, no picture

Yes, there is only one fuse (F1) on that T-CON board.

What is the component that I circled then?

[budm]

Re: LG 47LN5200_U: PWR, MAIN, and all LEDs replaced, no picture

Yes, there is only one fuse (F1) on that T-CON board.

[JDC]

Re: LG 47LN5200_U: PWR, MAIN, and all LEDs replaced, no picture

SMD = Surface Mounted.

I understand that but when you refer to the SMD fuse, are you referring to the F1 fuse in this case?

[budm]

Re: LG 47LN5200_U: PWR, MAIN, and all LEDs replaced, no picture

SMD = Surface Mounted.

[JDC]

Re: LG 47LN5200_U: PWR, MAIN, and all LEDs replaced, no picture

I am surprised that you ask if that is the SMD fuse we need to check the resistance you you have already did the Voltage test on it an it shows as below:

Post #16: F1 fuse on TCON:

ON .014 both sides
OFF 0 both sides

Right now per your measurement you do have continuity from L1100 (checked out to be <1 Ohm) all the way to both ends of the T-CON and you also have 12V at the output of the switched transistor so I do not know why you do not have 12V at the T-CON fuse.

So far we've been calling it the F1 fuse. Is it also called a SMD fuse?

[budm]

Re: LG 47LN5200_U: PWR, MAIN, and all LEDs replaced, no picture

I am surprised that you ask if that is the SMD fuse we need to check the resistance you you have already did the Voltage test on it an it shows as below:

Post #16: F1 fuse on TCON:

ON .014 both sides
OFF 0 both sides

Right now per your measurement you do have continuity from L1100 (checked out to be <1 Ohm) all the way to both ends of the T-CON and you also have 12V at the output of the switched transistor so I do not know why you do not have 12V at the T-CON fuse.

[JDC]

Re: LG 47LN5200_U: PWR, MAIN, and all LEDs replaced, no picture

Black probe on either end of L1100, red probe on one end of the SMD fuse of the T-CON board one end at a time, it should show <1 Ohm (set meter to 200 Ohm scale).

You mentioned a SMD fuse. Is that the one circled in red in the attached pic? If so, all combinations measure between .5 and .8.

[budm]

Re: LG 47LN5200_U: PWR, MAIN, and all LEDs replaced, no picture

Black probe on either end of L1100, red probe on one end of the SMD fuse of the T-CON board one end at a time, it should show <1 Ohm (set meter to 200 Ohm scale).

[JDC]

Re: LG 47LN5200_U: PWR, MAIN, and all LEDs replaced, no picture

He needs to check the resistance between that inductor against both ends of the SMD fuse on the T-CON to make sure it is connected all the way to the T-CON board.

It would probably be best at this point if you told me exactly how to do that. With the TV unplugged and my meter set to ohms, set one probe on what fuse? The other on what inductor?