lg 26LC2R lcd tv backlight turns off

[trutle]

Re: lg 26LC2R lcd tv backlight turns off

Hi there,

I have this same model of tv on my bench, exact same problem, backlight shuts off after 2 seconds of image.

Let´s see if together we can find whats wrong with this.

I already replaced the 2 inverters(master and slave) and still have the exact same problem.
I bought the inverters from a reclaim part in Uk, they are sold as 100% working and tested so i guess our problem is in other part.

I think i suspect the T-con board, because there is a small flat cable that goes from master inverter to that board, what do u guys think?

Thanks for all the help, and if it´s needed some mesurements or other stuff please tell me.

Luis Martins

[anno]

Re: lg 26LC2R lcd tv backlight turns off

I still didn't solve it. I tried to remove the cable from inverter to tcon and still same problem. Did you try?

[trutle]

Re: lg 26LC2R lcd tv backlight turns off

Hi again,

i have already tried that, same problem.
I also powered the inverters with the power supply simulating the signals with 100 ohms resistor and the problem persists. That made me think that the problem was in the inverters, so i replaced them, but still nothing has changed.

My lamps all light up, so i think there is no problem there also.

If we know what kind of signal to expect in the flat cable from the inverter to the t-con that would be great.

Thanks,
Luis

[budm]

Re: lg 26LC2R lcd tv backlight turns off

Can I see the picture of the T-CON board.

[trutle]

Re: lg 26LC2R lcd tv backlight turns off

This is a generic picture of Tcon, not mine actually, u can see on left the flat connection from inverter.

[budm]

Re: lg 26LC2R lcd tv backlight turns off

OK, I have no luck locating the spec sheet for the LCD panel LC260WX2-SLB3 to find out the signal on the connector between the T-CON and the master inverter board.*-SLB2 does not have that connection.

[trutle]

Re: lg 26LC2R lcd tv backlight turns off

Yes i know that.

Been looking in the master inverter. It seems there is an ic that protects the inverter, OZ99361.

Can someone shed some light on this, can´t find datasheet on it.

It seems it have some protection pins, need to know what voltage to expect.

Thanks

[drgiosap]

Re: lg 26LC2R lcd tv backlight turns off

Sorry for my bad English.
I have the same problem.
I work out like this:
I turn on tv in AV4 (or AV1, 2 or 3 it is important that nothing is connected);
If you're on TV or HDMI, change the input quickly before it turns off the backlight;
I look 1/2 minutes and step into AV1 (where I connected the decoder) and the tv works fine!
Perhaps it is a protection on the TCON or main board.

I want to ask two questions:
How many volts on the PSU: EL5 EL6 EL11 EL12 EL13 EL35 EL36 EL40?
I have read that there is a small button on the main board to reset all: really exits and where is?
Thanks a lot

[trutle]

Re: lg 26LC2R lcd tv backlight turns off

Hi again,

Ok i solved my problem. Can make the backlight work by bypassing the protection of the OZ99361.

Tryed before with an external power supply, and then, tooked 5V from the board and lowered it to 2,0V on pin 1 of the ic.

Tv is now working OK.

[drgiosap]

Re: lg 26LC2R lcd tv backlight turns off

Ok, thanks.
Is this bypass?
http://www.dtforum.net/index.php?topic=104328.0

But, why IC OZ9936 protects inverter?
This can cause more serious damage to the inverter and the lamps?

[trutle]

Re: lg 26LC2R lcd tv backlight turns off

Hi,

That bypass in the Dtforum doesn´t worked for me.

I have to lift the pin 1 of the OZ and inject there the 2,0V with a voltage divider made with resistors.

I guess the inverter protection is baddly designed, if you have a lamp that has a bad contact and the consumption past the pin 1 voltage we have the protection active.

I´ve measured the pin 1 connected to the board, and gives me 2,2V, witch seems to be enought to activate the protection.

The voltage at this pin must be between 1,95 and 2,0V for me or the inverter goes into shutdown.
My best guess is that some of the lamps with age tend to consume a little bit more and due to bad design the inverter goes into shutdown. That´s my opinion.

Thanks.

[drgiosap]

Re: lg 26LC2R lcd tv backlight turns off

I think you're right.
Since yesterday was presented a problem: no sound!
Thank you if you can give me some suggestions .
I measured the values on the psu and they are ok except on P201:

Pin 2 (ON) is 2,80v
Pin 13 (3,4v On) is 2,07v

I have doubts about these
Pin 5 IC is 4,67v
Pin 10 is 3,30v... ok?


Thanks for the tips

[drgiosap]

Re: lg 26LC2R lcd tv backlight turns off

How reset tv?

[trutle]

Re: lg 26LC2R lcd tv backlight turns off

hi,

If you have no sound must try other input to see if problem is still happening.

As for the voltages low in psu, you should check all the capacitors in the exit with an ESR meter and replace those with high Esr, it´s the most common problem in psus.

Fo reseting tv, i think i saw a menu in the tv that does that, other than that you mas have a service remocon or a jig that connects to the mainboard to do more advanced service level.

Hope this helps,

Luis

[drgiosap]

Re: lg 26LC2R lcd tv backlight turns off

thanks, i try to change old capacitors with low esr capacitors

[sutaryo]

Re: lg 26LC2R lcd tv backlight turns off

hi.
i have a lg 26LC2R lcd tv which backlight is turning off. there is 24v going to the inverter. when backlight off still 24v present. BL-ON voltage good too.

so i think there is a fault with the inverter or lamps. But I'm not familiar with these kind of inverters. I think it's EEFL. don`t know how to troubleshoot.
anyone have suggestion=

I got tha same problem too, but with different brand, Polytron PLM 24B67, the back light is on but sudenly off, and the BL on is off, but the sound is ok, could anyone have suggestion

[ludasm]

Re: lg 26LC2R lcd tv backlight turns off

Hi,

That bypass in the Dtforum doesn´t worked for me.

I have to lift the pin 1 of the OZ and inject there the 2,0V with a voltage divider made with resistors.

I guess the inverter protection is baddly designed, if you have a lamp that has a bad contact and the consumption past the pin 1 voltage we have the protection active.

I´ve measured the pin 1 connected to the board, and gives me 2,2V, witch seems to be enought to activate the protection.

The voltage at this pin must be between 1,95 and 2,0V for me or the inverter goes into shutdown.
My best guess is that some of the lamps with age tend to consume a little bit more and due to bad design the inverter goes into shutdown. That´s my opinion.

Thanks.

Hi,

I have the same problem. The bypass in the Dtforum doesn´t worked for me too. Please could you send me the resistors values. Thank you very much !!!

[trutle]

Re: lg 26LC2R lcd tv backlight turns off

Hi there,
I used a 10K resistor and a 22K pot. Turned pot until i got 2V reading on my meter.
Then lift pin 1 of OZ chip and inject the 2V. That sould solve it.
Thanks.

[ludasm]

Re: lg 26LC2R lcd tv backlight turns off

Hi there,
I used a 10K resistor and a 22K pot. Turned pot until i got 2V reading on my meter.
Then lift pin 1 of OZ chip and inject the 2V. That sould solve it.
Thanks.

Hi!
I made a mistake. I did not disconnect and lift up the pin 1 of OZ chip..
Now it works again! Thank you!

[JohnR]

Re: lg 26LC2R lcd tv backlight turns off

Thanks guys this worked for me.
Much cheaper and satisfing than a new tv!