LG 42LF66 Problem with Screen

[milicis]

Hi, can anyone please advise with some solution for this problem.

When tv is cold it starts fine, after few minutes goes blank, with backlight on and sound on. If I try to restart,
tv does like this (see video)

http://www.youtube.com/watch?v=CJ4syspjK8c

If Im not restarting right after it goes black, then sometimes after about 20-30 min trying to restart it, tv starts up fine, sometimes

with some stripes, but after restart  it again it works fine rest of the evening.

You can see in video that no backlight is coming on and remotely tv is not working.

http://www.youtube.com/watch?v=CJ4syspjK8c

P.S. I checked Caps visually.Cant see any faults.

[ProDave]

Most start up troubles are caused by PSU capacitors. Even if they don't look bulged, they may still be faulty.

Start there, possibly by buying a kit to replace all the capacitors on your PSU

[sparky]

hi
another test take back of being careful get hair drier warm
caps on psu if it springs to life change caps
dave

[milicis]

Thanks for answers.

When tv is cold it starts fine. Problem starts after few min-s. Seems caps are working like :
 

• Cold ( first few minutes) = good startup
• Warming up (next 30 mins) = no startup
• Warmed up (after 30 mins) = good startup

?

[scooby-doo]

TV Tony

Remove the ceratech filters on the main pcb and short across, they are 908,904,903,906,905,902, all are situated near the connector from the psu, p900. the chokes are preceded by fl. this is official from lg

The last 3 LG's I have done with start problems has always turned out to be the 4 2200uf 10v caps

[milicis]

Changed all caps no solution 

[mali67]

i have just changed a 680uf 35v in the psu , has the same fault , it cured the problem
it may be partially hidden under a screw on heatsink

[milicis]

i have just changed a 680uf 35v in the psu , has the same fault , it cured the problem
it may be partially hidden under a screw on heatsink

I have 35v 1000uf there under heatsink, changed, but problem still same .

[mali67]

andy from ohm supplies pointed me in the right direction with a similar fault.


http://www.ohmsupplies.co.uk/epages/62027733.mobile/en_GB/?ObjectPath=/Shops/62027733/Products/KIT153
 
Click on the link and check all the parts shown, this is a very common problem with this board, I think the cap in the PSU threw you off a little. From memory of you unplug the ldvs the backlight goes off so that lead to inverter. This model seemed to be very popular for a 37" but.the same fault happends on the 42 with it being the same board (again, from memory, please check)

I can't be 100% certain of a full cure but it would be the 1st thing I did to the set.

Regrads
Andy

[jordan]

Check this two 680uF capacitors on inverter board.

[Ohm Supplies]

Slow up.there.

I will look at the video of.the fault some time.but it.doesn't.sound like the same problem. I won't give advice or try to sell a kit if I don't think it will work. It's not what we're about.

.I'll advise later but please don't take the posting I've made out of context.

Regards
Andy

[Ohm Supplies]

Having looked at the video of.someone switching a plug then it looks like the set isn't coming on & I'd guess at a psu fault as the other engineers.have implied. From the description, yes, it could be a similar fault as kit 153, however with the 2 faults together then I'd look at the inductors.Tony recommends removing if they are fitted to your board.

I'd like to say that both of the last 2 methods require a certain level of skill to carry the job off successfully without ruining the board & writing.the set off.

Regrads
Andy

[mali67]

check to see if the top of the main board is getting hot.
I changed all the caps in that area as Andy indicated in the kit soley because i had narrowed it down to that area with a small fan.
The "kit 153" list it as a totally opposite fault to what i had but, The parts were in the correct area, i used electrolytic caps.
but will be getting the kit after the holidays to replace with the correct caps (like things looking nice)