LG 47 inch LCD TV,Black out, no picture ,no sound

[gracekel]

I have an LG 47LD690 LCD TV ,47 inch
there is a total black out, no sound no image, I tried to open the back cover ,there is no sign of any blown up capacitors, all the capacitors are flat and look ok, what could the fault be , so totally black just the red power light on the corner, the side buttons are not working.
no longer under Guarantee

 

[Lucid]

Have a look on Youtube to see if someone has posted a fix-it video for your model of TV.

 

[gracekel]

OK will do

 

[wotan]

Power supply module failure, search the internet - ebay I found one and replaced it myself cost approx £60, a bit cheaper than replacing the complete tv.

Wotan

 

[gracekel]

Hi, thanks,as it is or might be a power supply that failed,does it mean a board where the power socket goes need replacing as there seems to be 2 visible board only,maybe there is an hidden board somewhere (invertor

 

[yardie]

No video or audio then most likely the power board.
Usually a faulty inverter would give audio but no video.

Some power boards have an integrated inverter.

Without testing it would be hard to say for sure as there is the possibility of a faulty main board (audio/video board).

 

[Bosswhite]

I was going to post the same question, with our 42" LG, any update on this problem or is this a common problem with this TV.

Took it into TV Specialists, they reckoned dry Joint on the power supply board Worked for couple of months then the problem has returned only occasionally

I have found that by unplugging the set from the mains and leaving it unplugged for an hour or so , then replacing the plug it seems to "defreeze" the set and it works again,

 

[yardie]

Yes dry joint quite possible though caps still can't be ruled out.

 

[Askanison]

I have the same problem here, have a LG 50PZ570T tv and for some reason just wont turn on anymore, same thing happens just a black screen and no sound.
Red light comes on when i turn it on.

I opened it up and checked all the capacitors, but they all looked ok to me.
I read somewhere that some capacitors can still be bad even if they look ok.

Any idea how i can check whether the capacitors are what's causing the issue here?

Would love to get some help on this please.

 

[yardie]

Ideally you need a cap meter and an esr meter though an lcr is best.

Lack of experience and cost of tools limits testing but with a dmm you can at least check voltage stability and resistance ramping.

I think your problem is unlikely to be caps but check them anyway.

 

[Lucid]

Any idea how i can check whether the capacitors are what's causing the issue here?

Would love to get some help on this please.

Heat.
More specifically, a hot air gun / paint stripping gun.

Capacitors degrade over time. Poor quality ones degrade faster, but they all follow a pattern of falling performance. Depending where it is on the decay curve it might be possible to trouble shoot with some heat. Intrmittent caps can be coaxed back in to life briefly if warmed. If the cap isn't completely gone then the set might start. Work in sections starting with the power supply caps. A can of Freeze Spray is useful too for chilling the caps and for trouble shooting silicon.

 

[Sam Gangee]

Any idea how i can check whether the capacitors are what's causing the issue here?

See http://www.The-Cool-Book-shop.co.uk/electronics.htm#repair

Judicious use of a freezer spray and a hair dryer can help - if you understand exactly what you are doing.

Simplest way is to use an ESR meter, which will give you a definite answer. The cheap Chinese ones on eBay are probably adequate although I originally paid £200 for mine from America.

 

[Askanison]

Hi Guys,




Sorry for the late reply, been away, anyway, been looking online regarding some esr meters and not sure which one would be best to use for the capacitor checking i've narrowed it down to the few below and was wondering if i can get some advice on which would be best for testing purposes for my TV?

http://www.ebay.co.uk/itm/Portable-...350?pt=LH_DefaultDomain_3&hash=item43d8bbd566

http://www.ebay.co.uk/itm/MESR-100-...431?pt=LH_DefaultDomain_3&hash=item48623567af

http://www.ebay.co.uk/itm/MK-328-TR...607?pt=LH_DefaultDomain_3&hash=item43da09ca97


Not sure which one would help with checking the caps here, also had a look at some lcr's but they are quite expensive, im thinking might be cheaper if i just replace the whole board?

I read somewhere that the issues with black screens/no sounds is usually associated with the ysus board.

Since i dont have alot of experience with electronics, not sure which way to go here, i dont want to throw away a perfectly good tv here, even though its only 4 years old.

Cost me several hundred quid to buy it when it came out.

 

[Sam Gangee]

I would avoid the multi-purpose meters and buy an ESR meter. K.I.S.S.

 

[Askanison]

I would avoid the multi-purpose meters and buy an ESR meter. K.I.S.S.

Hi Sam,



Can you provide a few example esr meters i can have a look at (preferably good cheap ones)
And also any easy to follow guides on how to test the capacitors.


Cheers