T240 Monitor Backlighting Issue

[budm]

Re: T240 Monitor Backlighting Issue

1 & 2, 3 & 4.
BTW, the solder joints of the transformer legs do not look good, You my want to inspect the whole board.

[lizzrd]

Re: T240 Monitor Backlighting Issue

sorry for that... i do not have a edit option.

[selldoor]

Re: T240 Monitor Backlighting Issue

We prefer pictures to be posted using manage attachments so they remain on the thread
can you edit your post to remove and re attach

[lizzrd]

Re: T240 Monitor Backlighting Issue

After reading about the OP first post about screen blacking out, and disassembling, seems my board is a bit different. I am looking to check the transformer as shown in reply #4+5.
Any help on what solder points to check for resistance would be greatly appreciated...

[amt]

Re: T240 Monitor Backlighting Issue

Well Mine is fixed! I was on it the other day and one corner went black then with in 1 minute the hole thing was black. I could see that there was something on the screen but it was black. I opened the case and found a resistor with the board burnt around it, the inverter with a small melted spot on the top and the board burnt and the board starting to burn by the transistor on the back. I took off the inverter and could not find anywhere I could get a measurement and tried to open the case to see the connections inside. Luckily I wrote down the number first as it just kind of fell apart under force. I replaced it and bought caps for the ones next to it as I was sure they got pretty hot. They must of been cheap caps (the new ones)as they measured 950 each where the old ones were 820 and that is what they measured (No esr meter). Like I said, I replaced the inverter and the 2 caps and all is well again. Thanks for all of you that input into this topic as it let me learn how to fix this.
Thanks again.

[AndrakondrA]

Re: T240 Monitor Backlighting Issue

Hello,

After TSTB syndrome, replaced capacitors, ccfl lamps, (transformer (0.9K 1.0K secondary), still have a problem...
I decided to convert my LCD to LED, so want to disconnect the high voltage part of the board (don't want this part to consume electricity)

Questions:
-Can I totally disconnect high voltage part of the board and how?
- Is there any possibility to use monitor power supply to get 12v for the leds or must use independent power supply with independent switch?

Thanks in advance!

[g40rocket]

Re: T240 Monitor Backlighting Issue

A little update, i finally purchased my new CCFL tubes from http://www.ccflwarehouse.com


The Samsung T240HD is already in good working order.

Thanks to all that help me in this forum.

With 38 usd (including shipping) i fixed my LCD again !

[g40rocket]

Re: T240 Monitor Backlighting Issue

Hey fellows,

Sorry the delay.

I finally discovered my problem, it was the bulb, check the photo:





Is there any way to get this replacements or i have to buy a new backlight or panel ?

Thanks in advanced.

[johanneszab]

Re: T240 Monitor Backlighting Issue

I also wanted to say thanks for the contribution to this thread. It saved my T240HD which suffered on the TSTB symptoms. I've changed this capacitor and now it works like on its first day:
http://www.jzab.de/stuff/t240hd/kapu...ator_small.jpg

One different thing I wanted to ask is, what do you think of these wired substances on the other, system PCB i've noticed:
I've taken two images:
http://www.jzab.de/stuff/t240hd/board/board.jpg

Here on the left edge, it looks like the board corrodes and on the whole board surface, there is a sticky, orange fluid on it, looks like coke :P. I wonder where this comes from, and if i should remove it? I certainly never spilled any liquid over my TFT and because of the large amount, i think it was in there right from the beginning. It's only on that board, not on the other one though. The TFT is already 5 years old and worked till last week, so i though ignore the substances on it.

Here is an other picture: http://www.jzab.de/stuff/t240hd/board/board2.jpg

What do you think is that, just out of curiosity?

[afflux]

Re: T240 Monitor Backlighting Issue

Would have been helpful if you had referenced the picture showing the points as well.

It is sometimes worth testing off board before ordering.

Good luck with the repair - please update when complete

Was only just able to replace the transformer and test the device. Turns out the transformer was indeed faulty - now I have a working secondary screen again!

Thanks

[selldoor]

Re: T240 Monitor Backlighting Issue

Hello again,

There are spares for this or should i forget this LCD ?

How this happens ?

You can get replacement tubes - needs care and patience.
You can get tubes and pre-wired kits
It may just need the wire resoldered.

see this site for info http://www.ccflwarehouse.com/lasotu.html

Also earlier in thread someone re soldered but then broke the panel glass
https://www.badcaps.net/forum/showpo...2&postcount=28

It happens because they get very very hot -the insulation breaks down
then they start arcing and the wire burns. If you repair the insulation is very important, or it will not last.

[budm]

Re: T240 Monitor Backlighting Issue

It looks like the it has burnt wires that are attached to the ends of the lamps, one of the common failure mode.
http://s807.beta.photobucket.com/use...05283888095196

[g40rocket]

Re: T240 Monitor Backlighting Issue

Hello again,

Selldor, yes my readings with the digital multimeter was done in the points that post number 4 show in the photo.


Mariushm, i check the cables and here it is my photo:





There are spares for this or should i forget this LCD ?

How this happens ?

[selldoor]

Re: T240 Monitor Backlighting Issue

If red and yellow points are as in post 4 then that inverter transformer looks good. Check out the wiring and report back.

[g40rocket]

Re: T240 Monitor Backlighting Issue

Check the cable going to the light tubes.

Sometimes the wire gets loose/desoldered from the wire on the lamps and makes electric arcs and what you hear is the silicon or insulation burning up at the end of the lamps.

Thanks for the quick reply.

I will check that tomorrow (here it is 01 AM).

So, the inverter transformer is good right ?

[mariushm]

Re: T240 Monitor Backlighting Issue

Check the cable going to the light tubes.

Sometimes the wire gets loose/desoldered from the wire on the lamps and makes electric arcs and what you hear is the silicon or insulation burning up at the end of the lamps.

[g40rocket]

Re: T240 Monitor Backlighting Issue

Hi guys,

I read a lot of this thread and my Samsung T240HD has the two seconds go black sypmthoms.

Before the LCD goes faulty i noticed a burn smell when the TV was on and some flickering images.

Now everytime that i turn on the LCD, image is good but after two seconds i loose the backlight (image still runing background).

I already open the LCD but i don't see any burned inside.

I already measure the red and yellow points in the inverter transformer and i got this values:

Red = 1050 ohm
Yellow = 1050 ohm


Anyone can help me and tell me if the inverter is good or not ?

If not, what common faulty part is the next ?

Thanks in advanced.

[afflux]

Re: T240 Monitor Backlighting Issue

Sorry, picture is the attachment in this post: https://www.badcaps.net/forum/showpo...39&postcount=4

Unfortunately, I don't have a soldering station or similar equipment, so I couldn't test the component alone. I plan to give the transformer and the board to a friend once it arrived. Should have more info in three weeks.

[selldoor]

Re: T240 Monitor Backlighting Issue

Would have been helpful if you had referenced the picture showing the points as well.

It is sometimes worth testing off board before ordering.

Good luck with the repair - please update when complete

[afflux]

Re: T240 Monitor Backlighting Issue

epic.


YELLOW POINTS: 935 Ohm
RED POINTS: .594 MOhm (WOW)

So one of the transformer secondaries opened up?

I have the same symptoms as mucoast had, but

Red: ~930 Ohm
Yellow: ~1.7 kOhm

Since it's not close to mucoast's readings, but still not in the 3% tolerated diference, can I still assume the transformer is broken?


Edit: Only just realized that

Measured the resistance between the points like above:

Red: .930
Yellow: .605

Bad transformer. Plenty of information on getting a replacement in this thread.

PlainBill

Just ordered a replacement. Thanks.