Any TV engineers here please help

[stk2008]

Hi all I need some advice on my LG LCD screen please.

I got this TV about 1.5 years ago and for the last 5 or so monthes its been doing this

https://www.youtube.com/watch?v=rviqhRZvacA&feature=youtu.be

Now it dont all ways happen all day its very odd.
some times if I turn the TV on its ok for a little bit then its starts or sometimes it will get better through the day (I must add that the sound NEVER DROPS OUT ITS PERFECT) just the picture does what you see in the video.

Sometimes when the scene changes as you can see in the video the picture will come back and be perfect but then when the scene changes it can start to flicker or dissapear again.

But the really wierd thing is on the RGB (PC) connection its perfectly fine its does not do it at all with videos/games any thing so RGB is fine.
I have not been able to test the HDMI ports as I have not got any thing that uses HDMI.

I have had a look at the board the scart sockets go into and the solder points on the back look ok to me.


Please please advise.

 

[stk2008]

Any one please?

 

[StudentSA]

In my expert opinion that was a great GOAL! Also if you have tried hitting it in one or two sweet spots and that does not work... you need a new TV.

 

[dr pepper]

At first I thought the backlight inverter was faulty, but if you say its fine on rgb, then I'm gonna say that the rf receiver is probably the culprit, theres not a lot you can do without very fancy gear except check the connections etc.

Try another tv on the same aerial, just to make sure its not something silly like a fat seagull has bent your aerial.

 

[stk2008]

Hi there thansk for the feedback.

I have tryed a different TV and does not do it.

All so I have Virgin so its cable so I dont think its any thing to do with the RF.

Sorry my first post its wrong I did not mean RGB I meant VGA PC input is perfect.

Please advise any other ideas what it could be

 

[johansen]

take the back off and if you find any bulging capacitors, replace them, and then replace all of the capacitors which were manufactured by the same company.

 

[KG4MXV]

Seeing your OSD is stabile but the video is not I would try a different video input.
also the video from the VGA computer is perfect.
I would suspect the input is bad that you are using.

are you using a cable box with a HDMI cable
or a antenna?

I do not think you have video processor problem or a power supply problem.

You could have a bad cable or a loose connector.

I would move the signal cables and see if the problem starts or stops when you move the cables.

you might have a bad solder joint on the connector on the TV.

 

[tunedwolf]

It looks like either a video decoder or Tuner/IF problem on the main board.

 

[stk2008]

thanks for replying.

Would a faulty decoder not effect the VGA input as stated becasue the VGA input is perfectly fine its just scart socket 1,2 and 3.

like I said though I cant test HDMI as I dont have a HDMI device.

Would there be a simple part to replace on the decoder?.

P.S

Just to clear any thing up I use Virgin media so there is no arial so its not the arial in the TV giving me the issue its just the scart sockets.

I have tested with a DVD player and get the same issue.

It seems to now be getting worse.

Thanks

 

[dr pepper]

I have to argue with a previous post and say with the further info it looks like a video processor or power supply issue.
The power supply may be repairable, the video processor less likely, a new board or scrap job, unless your well experienced in telly repairs.
You might be able to use the vga input and keep it going a while longer, that starts to get complicated though.

 

[stk2008]

hi again.

If it was Power supply surley the VGA port would do it to?.

 

[dr pepper]

The supply probably has multiple rails supplying various circuits, one of these rails may be at fault.
That said I dont think I can diagnose at a distance any further on this telly, apologies.

 

[stk2008]

LOL totally understand if you could do that you would be mega rich .

Thanks all I will just use it as a moniter for now till I get the time to look closer.

 

[btsutton]

Do a visual inspection.

First do a visual inspection. I would open up the set and check all the connectors and look at the circuit board for a cracked solder joint or burnt components. You can re-flow any suspect solder joints. I am not a professional TV repairman but I have fixed a couple of sets like this. I once found a cracked pcb and had to jumper a couple of broken traces. It worked fine afterwards. Look for bulging electrolytic caps or cracked ceramics and resistors.
Make sure you unplug the set before working on it and be careful of any stored energy!

 

[stk2008]

hi there yeah I aint no expert on electonics but I have fixed the same tv 2 years ago bulging caps all of them on the main power supply board fitted new ones and worked perfect till a couple of monthes ago when this bloody problem started .

I will deffo look into it as I like the TV.

Thanks

 

[Zerotolerance]

I'd start by first checking for cold solder joints on the tuner board then check the caps. Check all voltages coming off the PSU without a load connected to them.

 

[stk2008]

Hi all ok managed to test HDMI and it works for a little bit then it just starts going crazy.

The only input so far that I have not seen any issues on is VGA as stated in my first post.

I am totally lost here.

Why would VGA be ok and all the others have issues?

 

[Nigel Goodwin]

Hi all ok managed to test HDMI and it works for a little bit then it just starts going crazy.

The only input so far that I have not seen any issues on is VGA as stated in my first post.

I am totally lost here.

Why would VGA be ok and all the others have issues?

Presumably (and fairly obviously) the fault is on the main board, and presumably requires the entire board replacing?.

 

[picbits]

If the telly is a year and a half old and you are based in the UK, I'd take it straight back to the retailer and ask for it to be replaced or repaired under the sale of goods act - the item hasn't lasted a reasonable time therefore isn't fit for purpose.

 

[stk2008]

hi thanks for getting back to me.

i dont think I told you all the full story

I got it second hand and when I got it it had a fault

It would not turn on for ages and whe on it was fine.

As I am sure you all know it was the capacitors on the PSU board
I replaced them all and it worked perfect for a year.
Now this has started and I am gutted as every thing else is great.

Should I look for a replacment board that has the VGA,Scart,HDMI ports on what is that board called?.

Thanks so much for your help