Samsung P2470HD Turns off

[Iersuo]

Hello! Got a Samsung LCD TV model: P2470HD which acts as following: Turns on, displays menu for 2 seconds, goes black... Sound effects of the touch buttons on the TV work, buttons themselves work, TV does not react, trying to change input source does not have an effect. Turn off and on again same thing repeats. Have been reading that this is commonly caused by a backlight problem, how can that be diagnosed? Any suggestions?

Thank you in advance!

[Iersuo]

Re: Samsung P2470HD Turns off

A little update: pointed a flashlight to the screen and the text of the menu is barely visible, so now I believe the problem is truly in the backlight. The problems began after the TV fell btw, but it was not a big fall and on the exterior of the tv there is really not a single sign of that. When the TV turns on, backlight lights up the whole screen and is as bright as normally would be, is that a sign that the light unit itself is operating correctly and some other part makes it turn off (fail-safe mode)? What should I look for now?

[Iersuo]

Re: Samsung P2470HD Turns off

Any idea where to start looking?

[Iersuo]

Re: Samsung P2470HD Turns off

After some further investigation I decided to take some measurements of the power board and try to diagnose if one of the power trails to the ccfl lamps is not providing sufficient power. I tried to connect 2 connections at a time and all the results are in the picture, lines indicating the connector that were connected and the letters indicating the brightness of the display the second it boots up (after which it turns off as I previously explained). Abbreviations for the letters: N-none (no backlight at all) ; D - Dim backlight ; B - Bright backlight (same level of brightness as when all of the connectors are in). I believe this is probably not enough of troubleshooting, so please inform me if further testing is needed and what exactly. Thanks!

[Iersuo]

Re: Samsung P2470HD Turns off

The issue was in the CCFL lamp. Will replace it soon and report again :P

[ReeceyBurger123]

Re: Samsung P2470HD Turns off

The issue was in the CCFL lamp. Will replace it soon and report again :P

Ok keep us updated.

[Iersuo]

Re: Samsung P2470HD Turns off

Replacing CCFL fixed the issue indeed!

[digitalblade]

Re: Samsung P2470HD Turns off

Replacing CCFL fixed the issue indeed!

Hi,

i've exactly the same problem! could you please tell me where the ccfl lamp is located on the monitor and the part number that i can search to purchase it in Europe ?

Thank you very much!

[attainteddragon]

Re: Samsung P2470HD Turns off

it is more likely to be an inverter issue if you are getting a splash of backlight and then the lights turn off. at this point can you make anything out on the screen if you shine a bright light on the screen?

pictures of the back of the set with the cover off and a pic of the ps and inverter board please.

[digitalblade]

Re: Samsung P2470HD Turns off

it is more likely to be an inverter issue if you are getting a splash of backlight and then the lights turn off. at this point can you make anything out on the screen if you shine a bright light on the screen?

pictures of the back of the set with the cover off and a pic of the ps and inverter board please.

thank you for you interest, my problem is that the screen going off after about 2 seconds, if i change channel on TV i continue to hear the sounds but the screen is completely black. If i turn off the screen and turn on again the picture appear again for 2 seconds that disappear but as before the sound still here!

thank you

[digitalblade]

Re: Samsung P2470HD Turns off

Hi, please find attached images as your request, i hope that this can be useful for helping me to diagnose the problem.

thank you very much!

[attainteddragon]

Re: Samsung P2470HD Turns off

a pic with all of the boards in the tv would of been good, but we can start from here.

i have marked out two sets of pins on the backlight transformer.
can you measure between each set of legs, (ohm. set meter to 20k, if it can't read it, increase the measurement till it registers on your meter), compare the two readings and let us know what they are.

it has odd output windings on it, normally it would be two left pins v's two right pins. so i hope that i got it right.

[digitalblade]

Re: Samsung P2470HD Turns off

I just measured the points and for both set I read 175.9K ohm

[attainteddragon]

Re: Samsung P2470HD Turns off

do you have a spare set of ccfl's that you can plug in to see if it is the backlights or not.

[digitalblade]

Re: Samsung P2470HD Turns off

unfortunately not i'm not a "real" repairer.. only an hobbyist guy with electronic skill :P this is a friend of mine monitor that yesterday evening suddenly stop working..

There are other measures that i can do to find the problem?

In the mean time i see that on the back of power board there is a SEM-2005 that is an inverter driver IC (check here here for schematics).

There is something that i can measure here? i don't have device schematics so i don't know what i can check.. I Read around the net that on pin 10 of SEM i must find 15V and on pin 11 something arount 2 volts. Measuring this point i find that with TV swiched OFF (the board outside the TV) i find 3 volts on pin 11 and 0 on pin 10

thank you for you help!

[digitalblade]

Re: Samsung P2470HD Turns off

do you have a spare set of ccfl's that you can plug in to see if it is the backlights or not.

just to be sure.. as ccfl you mean the entire board with the TM-08190 or only the transformer? because the transformer itself cost only 10 bucks so i can buy one to test it..

thank you

[attainteddragon]

Re: Samsung P2470HD Turns off

your transformer is good. i keep several spare sets of backlights to quickly test if the lights in the set, or relevant connections are any good.

there will be a feed back circuit that will tell the ps to turn off, but unfortunately, i havn't had time to look over it that thoroughly.

i'm not the biggest fan at trying to work out combo boards (ps with inverter), but i will try to see if i can give you any leads to go on, and others will chime in, i'm sure.

is your set the same as the op?

[digitalblade]

Re: Samsung P2470HD Turns off

your transformer is good. i keep several spare sets of backlights to quickly test if the lights in the set, or relevant connections are any good.

there will be a feed back circuit that will tell the ps to turn off, but unfortunately, i havn't had time to look over it that thoroughly.

i'm not the biggest fan at trying to work out combo boards (ps with inverter), but i will try to see if i can give you any leads to go on, and others will chime in, i'm sure.

is your set the same as the op?

sorry but i can't understand what you mean with "is your set the same as the op?" sorry but English is not my primary language :P

[attainteddragon]

Re: Samsung P2470HD Turns off

is this the same model as the original poster?

[vinceroger69]

Re: Samsung P2470HD Turns off

This video may help you understand ccfl sometimes its just the wiring on the ends of the tubes that breaks but please remember the lcd panel and tubes are very thin and break really easy
https://www.youtube.com/watch?v=hU218Frv6sA