Picture Fault LG 42LF66

[mali67]

ok i have the same problem again as pan, tv will stay on all day with the back off.
when i put the back on after about 20 mins a kind of interference starts then the picture goes off.
the back light stays on all the time, while there is sound just no picture.
Ive checked caps on psu and changed a few.
after lettng it cool down for a few mins I put a hot source on the main, t-con and psu boards one by one and cant get it to go off.

[Ohm Supplies]

If the ldvs is disconnected does the back light switch off?

[mali67]

ive narrowed the fault down to the top of the main board, where it looks like it has been getting hot ive put a cooling fan over that area with back on, been on for 7 hours

[Ohm Supplies]

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

[mali67]

well all those caps ar in the area, where the board has discoloured with heat.
Thanks for that Andy ill change those and post results

[mali67]

Fixed !!!
changed those caps and hey presto the tv has stayed on over night

Cheers Andy

[Ohm Supplies]

Like I said, very common but its so easy to blame everything else however once you've seen were the parts are then it should make sence as to why the picture is distorted. On the backer for the kit it also mentions an ic to solder for increased reliability & the 5v line on the set should be more stable (if you don't change it the set can bounce) its also not uncommon for one of the caps to pop while you unsolder it.

Did that happen with you?

Regards
Andy

[mali67]

no caps popped, but found them very hard to unsolder.
where was the info on the ic andy ?

[Ohm Supplies]

On the backer inside the kit, later versions of the board have a heatsink on it, or perhaps early versions had one & they took it off

Regards
Andyo