LG 47lv5500 no picture, possibly no sound

[vonbismarck]

I currently have a 47lv5500 that doesn't get display a picture. The TV had a broken screen when I first got it. It took me a while to find a replacement but was finally able to do so. The person I bought the replacement from said that it was working (can't remember if they said if it was new or not, it was a while ago). Because of family issues, I wasn't able to transfer anything over for a few months. When I finally did, the TV would turn on but no picture would/will show. The screen will light up when turned on, go black for a second or two and then go back to just displaying a lightened screen. I asked someone before if they thought it was the T-Con board but they thought it might be the panel. I a hoping it isn't the panel as it isn't really worth it to replace (the panel I bought is a sunk cost now).

Any ideas on what/where I should look/check? I can provide pictures if need wanted.

Thank you

Michael

[tom66]

Re: LG 47lv5500 no picture, possibly no sound

Can you tell if the backlight lights up or not?

[vonbismarck]

Re: LG 47lv5500 no picture, possibly no sound

Can you tell if the backlight lights up or not?

Hello. I want to say that yes, the backlight lights up. When I turn the TV on with the back off I see light when viewing it from the back.

[budm]

Re: LG 47lv5500 no picture, possibly no sound

Then we need to check and see if we do have DC voltage at both ends of the SMD fuse on the T-CON board next.

[vonbismarck]

Re: LG 47lv5500 no picture, possibly no sound

Then we need to check and see if we do have DC voltage at both ends of the SMD fuse on the T-CON board next.

Hello. Sorry, I was gone for most of the day. How do I go about checking the voltage? Should I provide a picture of the T-Con board?

Thank you

Michael

[vonbismarck]

Re: LG 47lv5500 no picture, possibly no sound

Then we need to check and see if we do have DC voltage at both ends of the SMD fuse on the T-CON board next.

Here is a picture of the T-Con board. Where/how do I check for voltage on both ends of the SMD fuse?

Thank you

[Caleb]

Re: LG 47lv5500 no picture, possibly no sound

Fuse is located between the white ribbons. Its white with brass ends says 3a on it. You should have continuity between the ends as well as about 12v on both ends when TV is on.

[vonbismarck]

Re: LG 47lv5500 no picture, possibly no sound

Okay, these are the results I got (hopefully I tested it right):

For continuity, the fuse is shorted (the meter beeped)

As for voltage, I was getting around .85 - .88 for each side. Obviously, nowhere near the 12V I should see.

Does this mean the T-Con board is bad or a different board?

[budm]

Re: LG 47lv5500 no picture, possibly no sound

That means the main board is not sending the switched B+ to the T-CON board, this switched B+ is fed through switched MOSFET on the main board close to the power pin of the LVDS connector (this connects the main board an the T-CON board through ribbon cables) of the main board.

[vonbismarck]

Re: LG 47lv5500 no picture, possibly no sound

That means the main board is not sending the switched B+ to the T-CON board, this switched B+ is fed through switched MOSFET on the main board close to the power pin of the LVDS connector (this connects the main board an the T-CON board through ribbon cables) of the main board.

Is this something that I would be able to replace? Also, does it sound like that is the only problem (i.e. if I replace the part/whole board, should the TV then work)?

Thank you

[Caleb]

Re: LG 47lv5500 no picture, possibly no sound

Close up pictures of the main board by the ribbon connections would be helpful in directing you where to test next.

[vonbismarck]

Re: LG 47lv5500 no picture, possibly no sound

Close up pictures of the main board by the ribbon connections would be helpful in directing you where to test next.

Hopefully this is will help.

[vonbismarck]

Re: LG 47lv5500 no picture, possibly no sound

Close up pictures of the main board by the ribbon connections would be helpful in directing you where to test next.

Hello. Was the picture I provided the one that you had asked for? Also, if the MOSFET can be replaced, how do I find the piece?

Thank you.

[Caleb]

Re: LG 47lv5500 no picture, possibly no sound

Yes that picture is fine, I would guess the ones labeled ic508 and ic504 are the ones your looking for, google the chip number and find a datasheet to get the pinout. You can report back the voltages present.

[budm]

Re: LG 47lv5500 no picture, possibly no sound

You can verify if those two devices are the switched to supply the voltage to the fuse on the T-CON board or not, juts check the resistance between the fuse on the T-CON and one of the pin on the device, it should show <1 ohms resistance.

[vonbismarck]

Re: LG 47lv5500 no picture, possibly no sound

Okay, I am able to get get voltages from ic504 and 508 but I can't seem to get any ohms. I don't know if I am doing something wrong or if that just means that they are bad. Also, though I am getting voltages, I still haven't found a datasheet anywhere to let me know what the voltages should be though I may have found a place selling them. Should I just order them?

[tom66]

Re: LG 47lv5500 no picture, possibly no sound

Can you list full part# of these IC504/508?

[vonbismarck]

Re: LG 47lv5500 no picture, possibly no sound

Can you list full part# of these IC504/508?

Hello. I have finally been able to get at least one of the part numbers. I can't seem to find a magnifying glass and my eyes are too bad to read the small print. I was able to use a macro lens but I still can't make out the number for ic508. You can see them in the picture. For ic504 I see: 2132MP -2.5G1 027J97

All I can see for ic 508 looks like: A27173 1043GGE (though I am not sure if any of that is correct).

Here is my question, is it pointless to replace these since I can't get the full part number for ic508?

Thank you

[Caleb]

Re: LG 47lv5500 no picture, possibly no sound

When you say you have no ohms, does that mean you have no resistance between the fuse on the tcon and those components? Do you have resistance from the fuse on the tcon to the connection on the other end of that same ribbon cable? it may be that those components are not the ones that are supposed to provide voltage to the tcon. As Budm said you can use the ohms mode to find what is connected to the tcon fuse on the main board by finding the low resistance connection.

the ic 504 appears to be an voltage regulator, i didnt get any hits on the number provided for ic508. data sheet for 504 attached

[vonbismarck]

Re: LG 47lv5500 no picture, possibly no sound

When you say you have no ohms, does that mean you have no resistance between the fuse on the tcon and those components? Do you have resistance from the fuse on the tcon to the connection on the other end of that same ribbon cable? it may be that those components are not the ones that are supposed to provide voltage to the tcon. As Budm said you can use the ohms mode to find what is connected to the tcon fuse on the main board by finding the low resistance connection.

the ic 504 appears to be an voltage regulator, i didnt get any hits on the number provided for ic508. data sheet for 504 attached

When I had tested for ohms, it was just between the fuse and those components. I just checked now for the other end of the ribbons cables. The cable at P1502 (not sure if that is how you describe it, the one under "reverse") I get no resistance but at the other cable there are some pins where I can get it give me around .4 ohms.