Samsung 2443BW Backlight/inverter problem

[dimwit]

Hello all.... On start let me just say that i'm no electrician,allthough I have some clues to what's going on...I have a Samsung Syncmaster 2443BW monitor that gradually started to go blank.First it just randomly went blank for a split second ..then after a minute or so the screen went blank.After I ruled out the graphic card,and computer,I concluded that the fault is in the monitor itself..It stayed blank no matter if i turn off the I/O button on buttonboard... Except if I turn off the power suplly on/off button on the powerboard ,I managed to get it lit again but only for a minute or so,then it goes black again.Then I reduced brightness to minimum,and it stayed lit for considerably longer time...something around 5 minutes.....I did the flashlight test and saw the picture,so that must mean ,that logic board is ok and that backlights were the problem, or at least the power supply to backlights,if i understand correctly...So after I opened it, I saw a couple of capacitors that were bulged...
I replaced almost all, except the main one (120u 450V) ,but to no avail... Here is picture of the power board..... So what else can i do? I don't actually know what or where the inverter is ... Please someone help me i'm desperate.. Could these parts from the second pic of the powerboard be responsible for fault??Should I replace them too?? I'm attaching pictures off all the boards ...

[budm]

Re: Samsung 2443BW Backlight/inverter problem

You have power supply-inverter board combination. Did you use low ESR type capacitors required for switching power supply?
Also post the pictures of the bottom side of the power supply-inverter board. Bad lamps (worn out or poor solder connections at the ends of the lamp), bad inverter transformer, etc.

[dimwit]

Re: Samsung 2443BW Backlight/inverter problem

Thanks for the reply .... Yes i've replaced them with low esr caps..here is the back side pic...

[dimwit]

Re: Samsung 2443BW Backlight/inverter problem

Ok so i saw something suspicious on the bottom solder connections of the inverter transformer... It looks like the connections are ''cracking'' ... and on the left one there is a visible burn... could this be a sign of a bad transformer??Would resoldering do any help?included a pic ..I don't know where to find a schematic of the board,and i dont know where to get the same transformer.....when i google the transformer model number i cant find any on the net....Any help would be much appreciated.

[budm]

Re: Samsung 2443BW Backlight/inverter problem

I would try re-solder all the pins of the transformer first.

[dimwit]

Re: Samsung 2443BW Backlight/inverter problem

Thank you Budm... It appears the problem has been resolved (knock on wood) I've re-soldered the transformer pins,as you suggested and just in case-I've replaced the main capacitor with a Rubycon one... So far the monitor is working like a charm..Can I ask what is the reason for those pin solder connections to crack and burn like that?Do you think it will happen again? Once again thank you for the input my friend... Will recommend this forum to everyone ..

[budm]

Re: Samsung 2443BW Backlight/inverter problem

Probably just poor quality workmanship.

[dimwit]

Re: Samsung 2443BW Backlight/inverter problem

I see.... well thanks again Budm...

[Lumberjack777]

Re: Samsung 2443BW Backlight/inverter problem

Also; they may have used lead free solder. Which will crack. I'd probably remove the solder from all the pins of the inverter transformer and replace all the joints with good ol leaded solder.

[dimwit]

Re: Samsung 2443BW Backlight/inverter problem

@ Lumberjack777..Yes that makes sense ...Will probably resolder all the crappy connections when it goes dead again,but for now i'm gonna leave it at that...im just so glad this worked ....thanks for the reply..

[dimwit]

Re: Samsung 2443BW Backlight/inverter problem

@ Lumberjack777..Yes that makes sense ...Will probably resolder all the crappy connections when it goes dead again,but for now i'm gonna leave it at that...im just so glad this worked ....thanks for the reply..

[dimwit]

Re: Samsung 2443BW Backlight/inverter problem

Ooops sorry for double post ..I really don't know how that happened..

[Caveman1]

Re: Samsung 2443BW Backlight/inverter problem

I would try re-solder all the pins of the transformer first.

Awesome!

I first resoldered the caps. (but mine were not even bulging)

I wish I read this post before buying a new board from china (they ended up sending me the wrong board too lol)

I saw 1 dark, looked burn solder joint on the transformer, I resolder that joint and it worked!