LG Help Required 42LG3000

[coopigeon]

Hi

I have just been given a 42" Lg3000 lcd tv with a problem . As far as i can see it will power up well red light will come on but no picture or anything. if i hit the input button on the side the red light goes brighter flashes then goes off , cant get passed this part. Apparently if you plug a dvd player in it will play sound but no picture but i cannot test this at them moment


Added small video of what the red light does when i press input button at side as i do not have the remote control for this set yet

https://dl.dropboxusercontent.com/u/...511_174146.mp4
any help would be greatly received

Attached some pics

[coopigeon]

Re: LG Help Required 42LG3000

Revised look at tv .. the red led is dull if i hit the input button on the side it brightens up flashes three times then goes off. At no point do the screen try to light up

[coopigeon]

Re: LG Help Required 42LG3000

Ok , i have picture if use flash light in dark but have sound ... anyway i can the inverter boards?

[tom66]

Re: LG Help Required 42LG3000

Have you 24V at the inverter boards?

[coopigeon]

Re: LG Help Required 42LG3000

Have you 24V at the inverter boards?

Hi Tom .. where do i check for this and do i need set powered up?

[tom66]

Re: LG Help Required 42LG3000

For a voltage check you almost always have the set powered up;
the pins on the inverter should be labelled but in any instance you can usually find the group of pins all connected together.

[coopigeon]

Re: LG Help Required 42LG3000

For a voltage check you almost always have the set powered up;
the pins on the inverter should be labelled but in any instance you can usually find the group of pins all connected together.

Ok i have 24.4volts at each inverter board for first 5 pins which looking at the wiring on the power board is correct

[coopigeon]

Re: LG Help Required 42LG3000

Ok , i have picture if use flash light in dark but have sound ... anyway i can the inverter boards?

should there be a voltage on the 2 wired white connectors leading to the outside of the telly ?

[stj]

Re: LG Help Required 42LG3000

if you mean the 2pin connectors going to the side of the panel - dont touch them.
those are the tube-drives, 300v+

[coopigeon]

Re: LG Help Required 42LG3000

if you mean the 2pin connectors going to the side of the panel - dont touch them.
those are the tube-drives, 300v+

roger that . Kinda freaky im watching it in the dark with a torch lol... tried disconnecting slave see if i could get a flash , tried disconnecting TCON no green led . just need to know either

1 how to get to ccfl area and check them caps out or check each inverter but dont know what to check for

2 how to check psu

3 was gonna just get a pair of inverters but reading some of the other threads this hasnt helped, as they dont historically go faulty together youd have thought disconnecting slave i might get 3 secs of life unless master gone.

[stj]

Re: LG Help Required 42LG3000

that's the first tv i'v seen with 2 invertors!

take them out & see if there is anything visibly bad on them under those covers.

maybe leave the covers off afterwards.
i know some of the large sony's had a design fault where the invertor overheated & failed because of a stupid plastic cover.

[stj]

Re: LG Help Required 42LG3000

check the invertor fuses.
small'ish white box on each inverfor marked "F" and a number.

[Alastair E]

Re: LG Help Required 42LG3000

Master/slave inverters, quite common for them to go faulty....

Check the BL-ON and BL-Dim pins, see what voltages on them....

[coopigeon]

Re: LG Help Required 42LG3000

that's the first tv i'v seen with 2 invertors!

take them out & see if there is anything visibly bad on them under those covers.

maybe leave the covers off afterwards.
i know some of the large sony's had a design fault where the invertor overheated & failed because of a stupid plastic cover.

Hi yeah master and slave . covers are off and secured with a single screw. Nothing obvious visually .24.4v pins 1-5 . do you know what the reading should be on the F1 ? just reading a generic LG thread where BUDM diagnosed a bad black F1 which was stopping the inverters firing up. If anything transformers look bit crappy on solder joints but they look same on both sides so dont think thats the issue

[coopigeon]

Re: LG Help Required 42LG3000

Master/slave inverters, quite common for them to go faulty....

Check the BL-ON and BL-Dim pins, see what voltages on them....

are these on the inverters alistair on th ewhite block connector prob pins 6-14 somwhere?

[Alastair E]

Re: LG Help Required 42LG3000

Of the 10 odd wires to the inverter, some will be Gnd, some 24V.

There'll be two or three that will be marked, BL-ON/BL-Dim/PWM

Its the BL-ON and BL-Dim you need to check the voltage on...

[coopigeon]

Re: LG Help Required 42LG3000

Taken this pic ,, Which is the BL-ON and BL-Dim pins? also the white fuse and black one in pic am i just checking voltage or some other setting?

[coopigeon]

Re: LG Help Required 42LG3000

Of the 10 odd wires to the inverter, some will be Gnd, some 24V.

There'll be two or three that will be marked, BL-ON/BL-Dim/PWM

Its the BL-ON and BL-Dim you need to check the voltage on...

pins 1-5 24.4v

pins 6,7,8,9,10,11,= 0 nothing

pin 12= 4.8v

pin 13=3.2v

pin 14 = 0

[coopigeon]

Re: LG Help Required 42LG3000

Hmmm the black F1 shows 24.4v one side and nothing coming out of the other although its a tiny end to get MM probe onto

[Alastair E]

Re: LG Help Required 42LG3000

So--with those voltages--Is the light on?

If not--suspect either of the inverters or the BL tube/s its/themselves...