Samsung SyncMaster 940NW - Half screen black, half colored lines

[andy91]

First sorry for bad english, i am from Croatia!

I have Samsung 940NW, so i decided that i want to fix it on my own, i have tools and everything but i need your help to tell me what should i check!

Problem is that half picture is black and other half is messed up with colored lines.
Also when i press power button i hear some buzzing and it need about 4-5 seconds to turn on. When he was working properly it will turn on immediately and there where no buzzing.

Yesterday i turned it on after long time(i already got new monitor so this is in box and not using) and first there were picture and everything normal, and then i turned it off and turned on again and then half picture black, half colored lines.

I didnt connect VGA cable, but you can see where it start black picture!

I will put pictures..

Could you tell me what should i check and replace of parts !?

Thanks

[selldoor]

Re: Samsung SyncMaster 940NW - Half screen black, half colored lines

Looks like panel may be bad but post good clear pictures of the boards inside.
If it is half black meaning only half lit it is surprising it stays on!
Does the menu work - please connect the vga and connect to a PC so we can see what it displays like.

[andy91]

Re: Samsung SyncMaster 940NW - Half screen black, half colored lines

Here are pictures. Menu works, but it is all messed up, but you can see it on center of screen

But now i see that half of screen isnt black, it is just dimmed, like lower brightness, and lines are moving over screen..

I think that screen/panel isnt broken because yesterday it showed normal picture

[selldoor]

Re: Samsung SyncMaster 940NW - Half screen black, half colored lines

I still think bad panel but you could check voltages on the voltage regulators IC600 and IC 602 top left on pic of Main/signals board. Also check the voltage on cap c306 near the lvds socket. Check and clean the pins on the lvds socket and the lead - both ends and also the socket on the panel board at the other end of the lvds.

Hopefully other will join in and comment

[andy91]

Re: Samsung SyncMaster 940NW - Half screen black, half colored lines

I marked on picture what i measured. Tell me if i measured wrong components

I wrote on picture what are voltages..

And now when i connected everything out of the case, from first board (supply) i heard buzzing all the time, i dont know which component but sounds really bad..
Is this good or it isnt?


What else could i measure? And are these voltages good or bad?

[selldoor]

Re: Samsung SyncMaster 940NW - Half screen black, half colored lines

You tested the correct components but I dont think you did the test correctly.
The clue is on the part number -33 means output should be 3.3 and -18 means output is probably 1.8v I think you have tested the input voltage.
See Here by retiredcaps
https://www.badcaps.net/forum/showthread.php?p=300999

What is the part number on the IC200 next to the cap you tested

[andy91]

Re: Samsung SyncMaster 940NW - Half screen black, half colored lines

Yes i tested it wrong, i put multimeter on left and right pin, now i put on right one and measured 3.3 and 1.8 as you said..

So voltages are right..

The mark on cap you said is A81SC Q712

[andy91]

Re: Samsung SyncMaster 940NW - Half screen black, half colored lines

Please help me, does anyone else have some advice?

[andy91]

Re: Samsung SyncMaster 940NW - Half screen black, half colored lines

So nobody have nothing to tell and help or explain??

Is it problem in main board(signal board), i found it on ebay for 17$ but i dont want to throw 17$ if it is not problem in her..

Please help

[momaka]

Re: Samsung SyncMaster 940NW - Half screen black, half colored lines

I had a problem with a Gateway LE1936 where the screen was either displaying garbage, fading out, displaying nothing, and just doing random stuff every once in a while. Turned out to be marginal caps on the 5V rail of the power supply. The monitor would turn on reliably and all, but the regulators on the video/logic board would drop out every once in a while and cause the havoc.

So start with the caps on the power board that filter the 5V rail. I think that would be by far the cheapest thing to try out first. If not, then it could be the main board or it could be a bad panel.

I'll be honest that I do think this looks like a bad panel problem... but you never know until you try something (preferably nothing expensive).

[andy91]

Re: Samsung SyncMaster 940NW - Half screen black, half colored lines

Okay, i will test all caps on supply board.. But that will be in few days, then i will post here what i found out..

Thanks