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

[JDC]

Ugh. I'm in a hole.

When my friend gave me this TV, the LG 47LN5200-UB would blink when it was powered on and nothing more. I blindly replaced the power board and main board. No change.

Further research showed that this model likes to blow LEDs. Sure enough, when I took in further apart, a couple LED strips were dead along with random other LEDs. I ordered a kit and replaced them all. Now the TV lights up and stays on, but nothing else. No picture.

What else can I look at here? I'm already a couple hundred dollars in the hole but I've learned a lot, so it's worth it in my book.

[dick_barton]

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

Can you return the items even if there is a small returns charge otherwise put them up for sale to recover some of your costs.

[JDC]

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

I could but I'd rather exhaust every option first. This was my first LED replacement and I'm rather proud that I didn't destroy it, lol.

[budm]

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

All the cables are properly back in place? You have DCV on the T-CON fuse?, etc.

[dick_barton]

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

So are you saying you no longer have a blinking standby LED and the backlights are definately on when viewed from the rear of the set, absolutely no doubt about the leds being on?

[JDC]

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

@budm I've literally double checked every connection. The TV comes on, the screen illuminates, and I hear static. As for checking the TCON fuse, can you be more specific?

I just wish there was a way I could test to see if the panel is garbage before I throw a new TCON board in it.

@dick_barton I have no doubt the LEDS are on. When I replaced the LED strips (all of them), it lit up like Christmas Eve in Vegas. They are on even after I put it back together (I'm rather proud of that! )

[budm]

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

We need to see the pictures of the whole back side of the TV to see how all the boards are connected together, then we need the picture of the T-CON board.

[JDC]

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

We need to see the pictures of the whole back side of the TV to see how all the boards are connected together, then we need the picture of the T-CON board.

Will do by Monday. Thanks!!

[ReeceyBurger123]

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

Delete.

[JDC]

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

Delete.

???

[ReeceyBurger123]

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

???

Didnt mean to comment on thread.

[JDC]

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

We need to see the pictures of the whole back side of the TV to see how all the boards are connected together, then we need the picture of the T-CON board.

Here you go. I took a closeup of the TCON fuses as well.

[JDC]

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

Bump.

[CapLeaker]

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

Umm... first off your pics are blurry.

Now there is a ribbon cable going from the PSU to the main board. There is a pin out on the PSU. Measure all those with the TV on and off and post the measured DC voltages with the corresponding pin out name.

Also try to turn on the TV and measure both sides of F1 on the Tcon against cold GND.

Report back.

[nicholas1110]

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

Hello,

I have had the exact thing happen to me on one of the first ones I've done LEDs on this model. Here is what happened to me. I take the tv down to the LEDs. Repair the LED strips as needed. I turn the tv on to check that all LEDs are working and rest the tv on the bottom edge. No I did not disconnect the tcon from the main board l, so when I tipped the tv up the ribbons to the panel touched the metal frame and shorted a component out on the main board. It was near the lvds connections smd square ic chip. So if you left the tcon plugged in and the ribbon cables in the tcon and tipped the tv up I would almost bet you shorted out the main board or something on the tcon from the ribbons touching the metal frame. If you took the ribbons off or unplugged the lvds cable then disregard my suggestion

[JDC]

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

Umm... first off your pics are blurry.

Now there is a ribbon cable going from the PSU to the main board. There is a pin out on the PSU. Measure all those with the TV on and off and post the measured DC voltages with the corresponding pin out name.

Also try to turn on the TV and measure both sides of F1 on the Tcon against cold GND.

Report back.

Using the main board pic I posted above as reference, from left to right:

ON

0
12.13
12.13
0
24.47
0
3.47
3.47
1.107

Off (but plugged in)

0
.007
.007
0
.004
0
3.55
3.55
0

F1 fuse on TCON:

ON .014 both sides
OFF 0 both sides

[JDC]

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

Hello,

I have had the exact thing happen to me on one of the first ones I've done LEDs on this model. Here is what happened to me. I take the tv down to the LEDs. Repair the LED strips as needed. I turn the tv on to check that all LEDs are working and rest the tv on the bottom edge. No I did not disconnect the tcon from the main board l, so when I tipped the tv up the ribbons to the panel touched the metal frame and shorted a component out on the main board. It was near the lvds connections smd square ic chip. So if you left the tcon plugged in and the ribbon cables in the tcon and tipped the tv up I would almost bet you shorted out the main board or something on the tcon from the ribbons touching the metal frame. If you took the ribbons off or unplugged the lvds cable then disregard my suggestion

I took the ribbons off the TCON when I was taking it apart but the connection from the TCON to the main board was left alone.

[dick_barton]

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

You appear to have no TCON voltage, so no picture. You need to follow the wiring back to the mainboard and find the supply. Use your meter to trace the connection from the TCON fuse down to the mainboard. The TCON supply is probably supplied from a switched transistor or mosfet that I suspect has been blown.

Edit
Please can you provide some sharp picture of your main board which would be of help.

[Diah]

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

from yours T-CON photo it show to me the left ribbon cable not correct sitting at the panel socket., take them both out and check the Gold pins of them, then reset them correct, as they labeled with hand writing they seem had story.

[CapLeaker]

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

Using the main board pic I posted above as reference, from left to right:

ON

0
12.13
12.13
0
24.47
0
3.47
3.47
1.107

Off (but plugged in)

0
.007
.007
0
.004
0
3.55
3.55
0

F1 fuse on TCON:

ON .014 both sides
OFF 0 both sides

Those are only half of the pin outs. There are 18 of them in total. We need all of them plus the pin out name!
However... there is no voltage going to the Tcon. no voltage there, no pic. Maybe disconnect the tcon and see if the voltage re appears on the connector.