Samsung Syncmaster T220 2 seconds to black

[Carbonic]

I'm new in self-repair. However I will try to keep it short and simple.
Info:
Samsung Syncmaster T220
Modelcode: LS22TWHSUV/EN
Produced: 2009
Problem:
When pressing the power button it takes 3 seconds until a picture appear, then that picture disappear after 2 more seconds. Using a flashlight I can see movement on the monitor so should be a backlight turning off issue.
Slogan on the box:
"Design That Performs" (..badly because of cheap components)

Troubleshooting
Done so far:

• Found the power board and looked it over. Sadly can't see any bad caps or anything malicious. Took 7 pictures if you want to look with your expert eyes.

Questions:
Now, I'm trying to get my hands on the needed tools. But before I have them I would like to find out precisely what to do.
Ok, I tried to read the guide at http://www.badcaps.net/forum/showthread.php?t=10419

While the caps looks fine I guess i will have to check those as well, don't know if I can get hold of a ESR tester or know how to use it.

I think i understand the mosfets, there's only one (IC102) and will test that as soon as i get my hands on a multimeter. As far as I understand I set it to 200ohm and check if it below 30. The same with the fuse/picufuse, where it has to be below 1.0ohm.

Now the "Bad inverter transformer" troubleshooting is causing me trouble. I don't know what to do. It mentions 4 pins but I seem to have 9 pins on each transformer like this:

Any comments on what I should do here?

These seem to be the most likely things to test before I go further down the guide. Any other things I should test?

Thanks in advance for any comments
/Carbonic

[Rtech]

The green fuse next to one of the transformers ???

[Carbonic]

Originally Posted by Rtech

The green fuse next to one of the transformers ???

Yes, should I test it in any way besides what I mentioned in my original post?

[Rtech]

If the fuse is good, then measure the resistance between A1 and A3 on each of the inverter transformers,the readings should be within 3-5% of each other..

[krlle]

Sorry for bumping an old thread, but were you ever able to fix this monitor?

I have the exact same issue with my Samsung T220, no capacitors show signs of bulging or leaking, and I have tried to replace two of the capacitors (those located in the middle bottom left corner above the screw hole) in this picture: http://badcaps.net/forum/attachment....3&d=1374764047

I have also tried to replace both inverter transformers, the TM-21240 ones, but with no luck. It's still exactly the same symptom.

The red power light comes on, the screen will turn on, and the screen comes on and shows the picture perfectly for 2 seconds before it goes black. I can see the picture if I use a flashlight.

In the last couple of months before the screen got like this, the top part of the screen would flicker erratically. It also was a little bit dimmer in this flickering part of the screen, this got worse with time until it got completely unusable with the 2 seconds to black symptom.

Any guidance would be appreciated. I have a multimeter which i can measure with if any of you can point out what to look for.

I feel like I can't give up on this now with this much effort put into it. Maybe I will try to replace the rest of the capacitors in spite of them seeming to be fine.

Kind regards,

krlle

[budm]

Originally Posted by krlle

Sorry for bumping an old thread, but were you ever able to fix this monitor?

I have the exact same issue with my Samsung T220, no capacitors show signs of bulging or leaking, and I have tried to replace two of the capacitors (those located in the middle bottom left corner above the screw hole) in this picture: http://badcaps.net/forum/attachment....3&d=1374764047

I have also tried to replace both inverter transformers, the TM-21240 ones, but with no luck. It's still exactly the same symptom.

The red power light comes on, the screen will turn on, and the screen comes on and shows the picture perfectly for 2 seconds before it goes black. I can see the picture if I use a flashlight.

In the last couple of months before the screen got like this, the top part of the screen would flicker erratically. It also was a little bit dimmer in this flickering part of the screen, this got worse with time until it got completely unusable with the 2 seconds to black symptom.

Any guidance would be appreciated. I have a multimeter which i can measure with if any of you can point out what to look for.

I feel like I can't give up on this now with this much effort put into it. Maybe I will try to replace the rest of the capacitors in spite of them seeming to be fine.

Kind regards,

krlle

Make a pair of test lamps:
http://www.badcaps.net/forum/showthread.php?t=19987

[petehall347]

could be a bad lamp ..think there is a way to force them on for testing only .

[jiroy]

Originally Posted by petehall347

could be a bad lamp ..think there is a way to force them on for testing only .

+1

[Carbonic]

No I never fixed this error. Bought a non-samsung monitor and have moved along.

[Ori]

I'm also having this problem hope to find the answer soon

[senndogg]

Originally Posted by Ori

I'm also having this problem hope to find the answer soon

Hi, Ori!

Please check if the 2 mosfets under the board are the AF4502C.

Changing these would fix the monitor in most cases.

[Ori]

Originally Posted by senndogg

Hi, Ori!

Please check if the 2 mosfets under the board are the AF4502C.

Changing these would fix the monitor in most cases.

Hi Senndogg,
Are those the 2 rectangle 8 legged things? How do I check them?

I managed to get a new Power board off ebay unfortunately it was poorly packed and arrived broken (PCB snapped) but it might be salvageable for parts

[senndogg]

Originally Posted by Ori

Hi Senndogg,
Are those the 2 rectangle 8 legged things? How do I check them?

I managed to get a new Power board off ebay unfortunately it was poorly packed and arrived broken (PCB snapped) but it might be salvageable for parts

Yes. Just check if "4502C"is written on them. In my experience, changing them has resolved issues with late 2000s Samsung monitors.
Desoldering and soldering is better achieved with hot air + solder gun.

[Ori]

Originally Posted by senndogg

Yes. Just check if "4502C"is written on them. In my experience, changing them has resolved issues with late 2000s Samsung monitors.
Desoldering and soldering is better achieved with hot air + solder gun.

Thank you I will get onto when I can

[televizora]

1. Replace lamps
2. Replace lamps with 12V LED stripe

[Ori]

Originally Posted by televizora

1. Replace lamps
2. Replace lamps with 12V LED stripe

Thank you I have seen the build for this, if it comes down to it yeah I think I will replace it with led strips hoping not to have to pull that part of the screen apart unless I really have to.

Originally Posted by senndogg

Yes. Just check if "4502C"is written on them. In my experience, changing them has resolved issues with late 2000s Samsung monitors.
Desoldering and soldering is better achieved with hot air + solder gun.

I looked at both the mosfets the numbers read
4525GEM on both the boards i have

[Ori]

Originally Posted by senndogg

Yes. Just check if "4502C"is written on them. In my experience, changing them has resolved issues with late 2000s Samsung monitors.
Desoldering and soldering is better achieved with hot air + solder gun.

I changed over the mosfets with the 2 off the new broken board but still no change. so it wasn't that, I also have tried it with the smaller controller board swapped for the new one and no change either so it isn't that. The inverters also seem to test ok.

[Ori]

the mosfets

[petehall347]

try using something to power the backlights . there are plenty of ready made driver circuits available .

[Ori]

Originally Posted by petehall347

try using something to power the backlights . there are plenty of ready made driver circuits available .

if the back lights come on for a few seconds at the start doesn't that mean they are working ?

Since my last post I have changed all the caps I could cept the big one, I changed the green fuse, I changed both the inverters, changed both the mosfets, I also tried a different logic board so that is also ruled out as faulty .... still the same doing more research atm