LG 42LC46 problem

[sienoki]

Hi guys n gals..im a newbie here so a big hello n happy new year.
I bought this model lcd tv from a friend ..it was completely dead..after opening it up there was 4 10v 2200uf caps bulged..so i replaced them with rubycon same values.It powered up fine and worked ok for 10mins then the picture would go but sound remains..the backlights would also stay on.
If i take the t-con board out then turn on i get the same result no picture only sound..could replacing the t-con board fix my issue..any help in my matter would be greatfully received..thx

[tom66]

Re: LG 42LC46 problem

I repaired this same TV (it's now my main TV.) It could be T-con, but double check your soldering on the capacitors is good. As the TV warms up, maybe the joints are cracking. Does the TV give a good picture for 10 minutes at a time? Try using a hair dryer to localise the fault if it is heat related. Also double check the LVDS connector is seated properly.

[sienoki]

Re: LG 42LC46 problem

Hi tom thx for answering back..am fairly sure solder joints are good i will check them again..yes i get a good picture for 10mins at a time..the LVDS is seated firmly in..Im totally new to electronics but have repaired 3 lcds been lucky they where only bad caps..think im gonna order a t-con board..theres only 1 on ebay thats from a smashed screen and he dosnt state thats it been tested so might take a chance on it..How would i use the hairdryer to localise the fault..thx

[tom66]

Re: LG 42LC46 problem

How would i use the hairdryer to localise the fault..thx

Get out the hairdryer, heat up individual areas around the capacitors, T-con and main board, if the fault shows then turn it off and test again, if it shows again then you have found the suspect area. Good for finding cold joints and bad capacitors (which don't always bulge.)

[sienoki]

Re: LG 42LC46 problem

I checked the solder joints and they are all good..i tried the hairdryer on t-con and main board with no results..ive changed 9 caps on psu from 35v downwards..would you also reccomend replacing the smaller caps on psu that are above 35v they also them crap named 1s..can t-con boards work for 10mins and just fail..thx
I bought a cap..diode tester from farnells on clearance shelf but dosent even work..i have a standard multimeter..thx

[sienoki]

Re: LG 42LC46 problem

I checked the solder joints and they are all good..i tried the hairdryer on t-con and main board with no results..ive changed 9 caps on psu from 35v downwards..would you also reccomend replacing the smaller caps on psu that are above 35v they also them crap named 1s..can t-con boards work for 10mins and just fail..thx
I bought a cap..diode tester from farnells on clearance shelf but dosent even work..i have a standard multimeter..thx

Hi..i have since replaced all caps on my psu..after 10mins still same so i then left it on for 30mins and picture is like photo..if i buy this t-con card and still same probs could some kind and patient soul walk me through how to use my multimeter and where to start as i am totally new to all this..thx
sos for crappy pics..

[tom66]

Re: LG 42LC46 problem

What capacitors did you use to replace the originals?

It could be a T-con fault. I've got a Samsung on my hands at the moment that has lines on the screen with no image visible, but sometimes after it warms up the picture comes back. I suspect the T-con is bad. It's possible, although unlikely, that bad caps could damage the T-con.

Can you list the ranges/settings your meter has - does it have a 20V or 40V range?

[sienoki]

Re: LG 42LC46 problem

ZL series of rubycon-ultra low impedance 5x10v-2200uf
the others are rubycon aswell apart from 2 panasonics 10v-470uf and 25v-47uf

[sienoki]

Re: LG 42LC46 problem

ZL series of rubycon-ultra low impedance 5x10v-2200uf
the others are rubycon aswell apart from 2 panasonics 10v-470uf and 25v-47uf

I met a bloke at farnells today in Leeds..he said he was a mod on here but didnt get his name as our lass was left outside for 30mins

[tom66]

Re: LG 42LC46 problem

Okay, those caps are fine.

Set the multimeter to the 20V range and measure all the outputs on the power supply.

[sienoki]

Re: LG 42LC46 problem

Okay, those caps are fine.

Set the multimeter to the 20V range and measure all the outputs on the power supply.

I will have to start my test another time as i use my bed to put tv on and now r lass is asleep in it..thx 4 ur help

[sienoki]

Re: LG 42LC46 problem

I will have to start my test another time as i use my bed to put tv on and now r lass is asleep in it..thx 4 ur help

The replacement t-con arrived today..installed it but still no joy
I wont pretend i know what im doing cos i dont..i feel im learning quite abit from other threads and definateley apreciate your help so far.
Now its time to start with my multimeter..on my psu there are 3 pin outs together..2 with the block wires going to the main board and 1 not in use..is that the test pin out..if it is i took readings when the unit is powered on(scary)as i dont to blow myself up..anyways readings are as followed
3.4v=3.47
GND=0.00
6.5=6.33
GND=0.00
12v=12.25
GND=0.00

[sienoki]

Re: LG 42LC46 problem

The replacement t-con arrived today..installed it but still no joy
I wont pretend i know what im doing cos i dont..i feel im learning quite abit from other threads and definateley apreciate your help so far.
Now its time to start with my multimeter..on my psu there are 3 pin outs together..2 with the block wires going to the main board and 1 not in use..is that the test pin out..if it is i took readings when the unit is powered on(scary)as i dont to blow myself up..anyways readings are as followed
3.4v=3.47
GND=0.00
6.5=6.33
GND=0.00
12v=12.25
GND=0.00

should i now take readings from the other 2 pin outs..if so do i need to take the block wires out and take readings with the set switched on..thx

[sienoki]

Re: LG 42LC46 problem

The replacement t-con arrived today..installed it but still no joy
I wont pretend i know what im doing cos i dont..i feel im learning quite abit from other threads and definateley apreciate your help so far.
Now its time to start with my multimeter..on my psu there are 3 pin outs together..2 with the block wires going to the main board and 1 not in use..is that the test pin out..if it is i took readings when the unit is powered on(scary)as i dont to blow myself up..anyways readings are as followed
3.4v=3.47
GND=0.00
6.5=6.33
GND=0.00
12v=12.25
GND=0.00

this is the picture after 20mins

[sienoki]

Re: LG 42LC46 problem

this is the picture after 20mins

Can any1 help me test further plz..i have 90quid in this set and would be a shame to get rid..thx

[tom66]

Re: LG 42LC46 problem

Can any1 help me test further plz..i have 90quid in this set and would be a shame to get rid..thx

Post a close up picture of the T-con... you may need to remove the shield.

I have a Samsung that has a strange picture occasionally, caused by a dodgy LDO (voltage regulator.)

[sienoki]

Re: LG 42LC46 problem

Post a close up picture of the T-con... you may need to remove the shield.

I have a Samsung that has a strange picture occasionally, caused by a dodgy LDO (voltage regulator.)

I will have to borrow a decent camera as mine is crap

[tom66]

Re: LG 42LC46 problem

I will have to borrow a decent camera as mine is crap

Even a crap picture might be enough to identify regulators on the T-con...

Here are what regulators look like. The three leg + large tab black devices are LDOs. In this set they are adjustable regulators, all of which are set to 2.5V.

The bottom one on this T-con failed, causing various colour lines on the screen + no visible image.

[sienoki]

Re: LG 42LC46 problem

I will have to borrow a decent camera as mine is crap

this is best pic at mo

[tom66]

Re: LG 42LC46 problem

this is best pic at mo

See my edit...