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

[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

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.

[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.

[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.

[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

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

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

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.

[dick_barton]

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

As budm says it is time for a recap so we all know the next starting point.

[JDC]

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

I think it would be best for us all if we called it a night for right now and start fresh again in a day or two. I really appreciate everyone's help and I apologize for not being more thorough. I'll do better next time, for sure.

[dick_barton]

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

I suspect Budm may be eluding to the fact that when you replaced the original fuse and had the led blinking this was probably due to the faulty led strip in the backlight.
Once you repaired the backlights I would have expected you TV with it's original boards to be working.

[JDC]

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

I suspect Budm may be eluding to the fact that when you replaced the original fuse and had the led blinking this was probably due to the faulty led strip in the backlight.
Once you repaired the backlights I would have expected you TV with it's original boards to be working.

Worth a shot if I can get a hold of the original boards. I started working on this TV a month ago. I'll need to look for them.

[budm]

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

At this point we know the power supply and the LED driver are working so you can leave the power supply board in place, I would put the old main board back in place and go from there.
BTW, and no one else had worked on the TV before you received it, we hope.

[CapLeaker]

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

Yep... change that main board out for the original one. If you have a oscilloscope handy, you could try measuring the LVDS, if the TV turns on.

[budm]

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

BTW, it took a little over 30 posts (starting at post 33) just to find out that the DCV measurement were made wrong on the T-CON board, I almost got to the breaking point, I knew it was the measurement error when it did not make any logical sense in the readings results.

[Diah]

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

I hear static (snow) when I turn it on.

if you put the original main board, will be easy to check after this static, by moving the load from MB step by step.

first disconnect LVDS from MB side, and check, static remain or not, if no more you hear. then put back LVDS to MB and disconnected LVDS from T-CON and check.. still you hearing the noise mean LVDS, if static no more, go further to T-CON and so on till the ribbon cable to LCD,

if at the first point of LVDS disconnected from MB and remain to hear static noise, then disconnect the speaker and check them of shorted. if they are well.. disconnect the IP section and check..

this is easy way. if your measurement way you have lack or not sure of them.

[CapLeaker]

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

BTW, it took a little over 30 posts (starting at post 33) just to find out that the DCV measurement were made wrong on the T-CON board, I almost got to the breaking point, I knew it was the measurement error when it did not make any logical sense in the readings results.

Wouldn't be the first time we got a run around.

[JDC]

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

Originally Posted by budm
BTW, it took a little over 30 posts (starting at post 33) just to find out that the DCV measurement were made wrong on the T-CON board, I almost got to the breaking point, I knew it was the measurement error when it did not make any logical sense in the readings results.

Wouldn't be the first time we got a run around.

I feel bad enough, guys.

[JDC]

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

I put the original main board in, same result except now I don't hear snow from the speakers.

This has to be a bad TCON board.

[JDC]

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

if you put the original main board, will be easy to check after this static, by moving the load from MB step by step.

first disconnect LVDS from MB side, and check, static remain or not, if no more you hear. then put back LVDS to MB and disconnected LVDS from T-CON and check.. still you hearing the noise mean LVDS, if static no more, go further to T-CON and so on till the ribbon cable to LCD,

if at the first point of LVDS disconnected from MB and remain to hear static noise, then disconnect the speaker and check them of shorted. if they are well.. disconnect the IP section and check..

this is easy way. if your measurement way you have lack or not sure of them.

I can try that but before I do, I want to clarify what I mean by static: it's the white noise you hear when the TV isn't tuned to a good channel.