Samsung SyncMaster T240HD flickering backlight, then 2 seconds to black

[MaxiKing]

Hello everybody,

eventually my good ol' SyncMaster T240HD is affected by the infamous 2 seconds to black like many others out there... A bit more factual, this is what happened / happens:

For some months now, occasionally the display flickered for some minutes after turning it on. By flickering I mean, that the picture from my PC was clear and crisp as always, but the brightness was varying quickly. The flickering only occured after turning on the display and always stopped after a while. The problem was not reproducible, so it did not occur everytime.

As mentioned before, now the display shows the typical 2 seconds to black behaviour - i.e. turn on by pressing the touch button in front; display shows picture or at least the input source box in top left corner; after 2 seconds the display turns black but the device is still on. Some time after the error occured for the fist time, the display turned on normally and I could use it for some time. But most of the times it fails to turn on with the 2 seconds to black error.

While crawling all the other "2 seconds to black"-posts here (especially for Samsung displays), I've learned about the most typical cause for this problem, the inverter transformer T301 being broken in some kind of way. So I checked the secondaries (whatever that means =) ) and the resistance between them was around 1k Ohm each (S1>S2 & S3>S4), so they should be fine. Resistance between primaries was pretty low (my multimeter is really antiquated, so I can only say that it was below 10 Ohm... But as you can see in the pictures of the power supply board (IP-58155A) the area around the resistor R301 looks burnt. As far as I can see, this is the only visible damage to the whole board. The caps look all right, there are no other burnt spots or obviously damaged components.

So my questions are, what could be the cause for the 2 seconds to black error. And what could be the cause that the display works some times, when it was switched off for some hours. Could there be a problem depending on the temperature? And what effect could the burned resistor R301 have and what could be the cause for it to get so hot?

Kind regards
Max

P.S. I tried to check the fuse F301 and it was under 10 Ohm (I've already mentioned my insufficient multimeter...), so it is probably ok?

[stj]

Re: Samsung SyncMaster T240HD flickering backlight, then 2 seconds to black

how old is it, and does the menu system tell you how many hours it's been used?
flickering makes it sound like the cfl tubes.

you should resolder that resistor btw,

[MaxiKing]

Re: Samsung SyncMaster T240HD flickering backlight, then 2 seconds to black

how old is it, and does the menu system tell you how many hours it's been used?

It's from April 2009. I was not able to enter the system menu, because none of the combinations I found in all those forums seemed to work. Or I was just not able to see it, because the screen is black anyway.

flickering makes it sound like the cfl tubes.

How can I check if the CCFL tubes are the problem? I tried it each with only one of the cables attached (for the upper half and for the lower half of the screen) but it always was the same behaviour.

you should resolder that resistor btw,

Done. Unfortunately this didn't make it any better, but it feels better ;-)

Another thing I've noticed while the back cover was removed was, that when the backlight (CCFLs?) turned on, there is a quiet hissing sound. When the backlight turns off, the sound is gone.

Thanks for your help so far!

[stj]

Re: Samsung SyncMaster T240HD flickering backlight, then 2 seconds to black

i bet the panel smells like ozone near one corner when it hisses too.
last time i saw that description the tube connection was arcing at one of the tube ends.

[budm]

Re: Samsung SyncMaster T240HD flickering backlight, then 2 seconds to black

You probably have bad wiring on the ends of the lamps, for examples:
http://s807.photobucket.com/user/bud...?sort=3&page=1

[repairgal]

Re: Samsung SyncMaster T240HD flickering backlight, then 2 seconds to black

Hello everybody,

eventually my good ol' SyncMaster T240HD is affected by the infamous 2 seconds to black like many others out there... A bit more factual, this is what happened / happens:

For some months now, occasionally the display flickered for some minutes after turning it on. By flickering I mean, that the picture from my PC was clear and crisp as always, but the brightness was varying quickly. The flickering only occured after turning on the display and always stopped after a while. The problem was not reproducible, so it did not occur everytime.

As mentioned before, now the display shows the typical 2 seconds to black behaviour - i.e. turn on by pressing the touch button in front; display shows picture or at least the input source box in top left corner; after 2 seconds the display turns black but the device is still on. Some time after the error occured for the fist time, the display turned on normally and I could use it for some time. But most of the times it fails to turn on with the 2 seconds to black error.

While crawling all the other "2 seconds to black"-posts here (especially for Samsung displays), I've learned about the most typical cause for this problem, the inverter transformer T301 being broken in some kind of way. So I checked the secondaries (whatever that means =) ) and the resistance between them was around 1k Ohm each (S1>S2 & S3>S4), so they should be fine. Resistance between primaries was pretty low (my multimeter is really antiquated, so I can only say that it was below 10 Ohm... But as you can see in the pictures of the power supply board (IP-58155A) the area around the resistor R301 looks burnt. As far as I can see, this is the only visible damage to the whole board. The caps look all right, there are no other burnt spots or obviously damaged components.

So my questions are, what could be the cause for the 2 seconds to black error. And what could be the cause that the display works some times, when it was switched off for some hours. Could there be a problem depending on the temperature? And what effect could the burned resistor R301 have and what could be the cause for it to get so hot?

Kind regards
Max

P.S. I tried to check the fuse F301 and it was under 10 Ohm (I've already mentioned my insufficient multimeter...), so it is probably ok?

Hi,

I have the same issue with the ozone smell and burnt resistor R301, R302 and T301.Would you know the value of those resistors? We replaced the inverter T301 but the smell is still there and R301 gets very hot. Did you resolve your problem, if so can you help us.

Thank you,
Repairgal

[budm]

Re: Samsung SyncMaster T240HD flickering backlight, then 2 seconds to black

R301, R302: 390K
The board is BN44-00226A (IP-58155A) about the same as BN44-0026C (REV C).
If the lamps are worn out it will burn up the inverter transformer.

[caz3126]

Re: Samsung SyncMaster T240HD flickering backlight, then 2 seconds to black

Hi,

I have the same issue with the ozone smell and burnt resistor R301, R302 and T301.Would you know the value of those resistors? We replaced the inverter T301 but the smell is still there and R301 gets very hot. Did you resolve your problem, if so can you help us.

Thank you,
Repairgal

Did you ever find the value on the resistor? I too now facing that problem. I have a 25" and a 23", so I wonder if its possible that they both carry the same resistor? was think I can get the value off it.
I know its an old thread, but I hope someone help.

[DrTerrier]

Re: Samsung SyncMaster T240HD flickering backlight, then 2 seconds to black

Piggybacking on the thread, just checking if someone could help me.

I had the same issue: turning it on, had screen uptime with a buzzing noise, then no image with power on. I tried to diagnose the issues, and changed the inverter to a new one to no avail. Then replaced all of the caps, which still didnt fix the issues.

After that I moved to the CCFL´s, but I´m not entirelly sure if they are the problem. As you can see fromTHIS video, the CCFL´s are trying to light up, but they just flicker. Should I replace them?

Thanks in advance.

[robzz]

Re: Samsung SyncMaster T240HD flickering backlight, then 2 seconds to black

Piggybacking on the thread, just checking if someone could help me.

I had the same issue: turning it on, had screen uptime with a buzzing noise, then no image with power on. I tried to diagnose the issues, and changed the inverter to a new one to no avail. Then replaced all of the caps, which still didnt fix the issues.

After that I moved to the CCFL´s, but I´m not entirelly sure if they are the problem. As you can see fromTHIS video, the CCFL´s are trying to light up, but they just flicker. Should I replace them?

Thanks in advance.

Necro-ing an old post because it helped me. Had somewhat close problem (buzzing, major artefact image).

Posting root cause for mine since this post helped me sort it out. It was the CCFL connection that came loose. It was burned. Probably bad QA or bad design. Artiefacts were probably caused by flickering power supply caused by bad connection.

It was the CCFL of the top. The one with the large black tape holding the return wires of CCFL.

Also, to repair it, all I did was clean the burnt wire, redo the solder. Those connection are encased in white silicone. I cut the side to remove the wire and CCFL. Redid the solder outside of silicone and slide them back in. Also, dont forget to put some electrical insulation because there is bare metal very near once you put it back toghether. I just put some electrical tape on the metal instead of trying to tape the silicone.

Hope it help!