LG 47lv5500 no picture, possibly no sound

[Caleb]

Re: LG 47lv5500 no picture, possibly no sound

Ok, so from the pins on the main that give you .4 ohms look for another .4 ohm reading to a nearby ic or transistor. (it may be on the other side of the board as well)

[vonbismarck]

Re: LG 47lv5500 no picture, possibly no sound

Ok, so from the pins on the main that give you .4 ohms look for another .4 ohm reading to a nearby ic or transistor. (it may be on the other side of the board as well)

Okay, I tried to do what you said but I am guessing I failed. I could only get readings on ic506 and ic507 but I was getting a reading of 48 ohm not .4.

[nmonline86]

Re: LG 47lv5500 no picture, possibly no sound

Have you found the issue? I have one that the screen will turn on but will only have a couple grey stripes appear vertically on the screen.

[tibimakai]

Re: LG 47lv5500 no picture, possibly no sound

I have a 42" and I have found half way unbonded tab, at the panel between the panel's PCB and tab.
I have the same backlight with no image at all.
Gamma reading on the T-con are weird. There are some gaps in the measurements. By gaps, I mean there are at least three measuring points where the voltage is 0V.
I have picked up this TV from somebody, who already messed with it, so I'm not sure if he messed with the panel or not.

[Masba]

Re: LG 47lv5500 no picture, possibly no sound

Hi all, just got similar model tv (47lv550W) with no picture but working audio situation, back light is working.

First thing I tested the T-CON fuse TV unplugged. It gave 1 ohms so figured out its ok, althought there is no voltage when TV is switched on.

Next thing I tested voltages in PSB, picture attached. All voltages were normal except PWR ON, I quess it should be 24v but only got 3.3v instead.

So my logic says there is something broken in the PSB. Anything I could do to fix it or should I order new one straight ahead? Can bad caps do this?

http://www.ebay.com/itm/LG-EAY621698...item4adaf59f5a

[Masba]

Re: LG 47lv5500 no picture, possibly no sound

Ach, dunno why I thought PWR to be 24v... Guess 3.3v ok. TCON fuse shows 9.9V at both ends when TV on. Earlier owner already tried with two different TCON's, both a no-go. So now I'm beginning to think im stuck with a bad panel?

[Caleb]

Re: LG 47lv5500 no picture, possibly no sound

Nothing at all on screen? Could be the main board is not sending signal to the panel. You can typically slowly remove the tcon connector while the set is running pulling one side out slightly further than the other. As it loses connection usually you will see lines flash on screen. If you will see lines tcon is usually OK.

[Masba]

Re: LG 47lv5500 no picture, possibly no sound

Yeah, nothing at all on screen. TV responds normally to remote and fixed buttons, volume control works etc.

Do you mean the cables coming from main board or cables going to panel? Is it safe to pull them when tv is on?

I measured following readings on TCON testpoints:

P_VDD: 0v
GMA1...9: 0,02v
GMA10...18: 0v
VCC: 3,28v
VDD: 0v
VGL: -1,55v
UC1: 0v
VGH: 0v
VST: -1,55v
VGH_EVEN: -1,55v
VGH_F: -1,55v
GCLK1...6: -1,55v
VCOM: 0,26v
Z_OUT: 0v
VCOMRFB: 0,26v
GIP_RST: -1,55v
VGL_1: -1,55v
VGH_ODD: -1,55v
VGH_R: -1,55v
E0: 0v
GST: 0v
MCLK: 0v
GCLK: 0v
VCORE: 0,99v
VIN: 9,72v
HVDD: 0v
SOE: 0v
VST_IN: 0v
OPT_N: 0v
VCOMLFB: 0,26v
PDL: 0,04v
H_CONV: 0v

Can you say anything from those? Attached is picture of the TCON. Large IC on the center does not warm up at all, is that normal? I can hear faint buzzing noise coming from TCON when listening carefully.

[Masba]

Re: LG 47lv5500 no picture, possibly no sound

One more observation for the night: TCON fuse gets 9,9v on both sides even when tv is switched off, normal?

[Caleb]

Re: LG 47lv5500 no picture, possibly no sound

Most of ours over on this side of the pond run on 12v, but 9v may be fine as I've seen them run on 5v. I would try the lower left connector tipping the left side out first so the signal is lost before power. Yes TV should be on, don't tip the connector too much or you could short the pins, losing power should cause no damage.

[Rocketman321]

Re: LG 47lv5500 no picture, possibly no sound

Hi,

I've got a similar problem with a 37LV5500. The difference is I do not get any voltage to the TCON board, VCC = 0v. Power supply is working ok, but there is no sound on my tv, also the backlight of the LCD won't light up.

Also, it isn't clear for me, if the 12v the TCON gets. Is given when the mainboard initialized his own systems.

Any suggestions?

[Caleb]

Re: LG 47lv5500 no picture, possibly no sound

12v for tcon is derived from the main board, I would look at the voltage regulators on the main board and verify they are working then trace back the source from the tcon fuse to the main board. Usually it will go to a fet that switches on the power to the tcon.

[jlrsbcnet]

Re: LG 47lv5500 no picture, possibly no sound

Thanks for the information Guys, I have a 47LV5500-UA, Not video, not sound.
The 3.5v, 12v, 24v, in the P501 on Mainbord, but any voltage in the T-con board.
The problem it's on the Main Control Board.

Thanks guys any info about schematics and troubleshooting let me know.