Samsung SyncMaster 2443BWX Comes Up, Goes Down and On and On

[Stingray75]

This monitor comes up like normal but then the display flickers and goes black. Five or ten seconds later it comes back up and does the same thing again. The blue light stays on the entire time.

I've already taken it apart and looked at the caps on the power supply. No obvious problems except for one cap that looks like it might be just barely starting to bulg. The caps are Samwha.

Is this a power supply problem or something else.

Thanks, this is my first post.

[retiredcaps]

Re: Samsung SyncMaster 2443BWX Comes Up, Goes Down and On and On

Pictures of your boards help us help you. Follow my instructions below exactly.

You will also want to make DC voltage measurements on the connector of your power board.

[Stingray75]

Re: Samsung SyncMaster 2443BWX Comes Up, Goes Down and On and On

Thanks for the reply Retiredcaps. I will try to post some pictures today. Before I get the monitor back out and plug the power supply back in I was thinking that I would go ahead and replace at least the high failure caps on the board. I haven't found much on the site for this model of SyncMaster. It has power supply BN44-00238A. Does anyone have schematics for this power supply and the other boards in the monitor? Thanks

[budm]

Re: Samsung SyncMaster 2443BWX Comes Up, Goes Down and On and On

BN44-00237A may be close to what you have.
http://www.toms-service-manuals.com/

[Stingray75]

Re: Samsung SyncMaster 2443BWX Comes Up, Goes Down and On and On

OK, here are some pictures.

http://www.jcbosworth.com/Photograph...0243601_xJs8nd

Here are the voltages.

1. 5
2. 16
6. 5
7. 5
9. 2.9
10. 3.3
11. 2.8
12. 1.7

To get the voltage measurements I had to disconnect one of the cables. This can be seen in one of the pics. The monitor comes up for a few seconds then flickers and then goes black. I tried looking in with a flashlight but couldn't see anything. The blue light always stays on. After it is off for 5 or 7 seconds it will come back up on it's own but then stay on a little bit shorter of time and go back off. After it does this a few times it pretty much stays black.

Another thing I noticed is when it is on and there is an image on the screen you can hear a slight noise. This noise seems to be coming from the right lower corner of the display where the black wires go in.

[Rtech]

Re: Samsung SyncMaster 2443BWX Comes Up, Goes Down and On and On

On the photo attached check resistance between the two RED marked pins,and then between the BLUE marked pins and advise.Also I suspect from your last paragraph that the problem is the Backlight and/or its wiring that goes to the right lower corner.

[Stingray75]

Re: Samsung SyncMaster 2443BWX Comes Up, Goes Down and On and On

Rtech, both are 1K.

[Rtech]

Re: Samsung SyncMaster 2443BWX Comes Up, Goes Down and On and On

Then the probability is that either the wiring or the backlight/s associated with that bottom right corner is the cause of the problem.Arrange the Screen so that the both top and bottom sets of Backlights change position, and then see what happens..that should confirm the cause prior to taking the screen apart to get to the lamps

[Stingray75]

Re: Samsung SyncMaster 2443BWX Comes Up, Goes Down and On and On

What is the proper way to take voltage measurements on the power supply? I had to disconnect one of the cables to get my readings.

[Rtech]

Re: Samsung SyncMaster 2443BWX Comes Up, Goes Down and On and On

I would not worry about that until you try what I suggested with the screen !!

[Stingray75]

Re: Samsung SyncMaster 2443BWX Comes Up, Goes Down and On and On

Sorry!! Just wanted to make sure I did what RetiredCaps asked me to do properly.

[Stingray75]

Re: Samsung SyncMaster 2443BWX Comes Up, Goes Down and On and On

Rtech, tried doing what you asked but couldn't arrange the screen in such a way that all the wiring would reach. I was able to plug the bottom backlights into the top connector without the other one plugged in and vice versa. The static noise heard at the bottom right of the screen went away of course without anything plugged into it. When plugged into the top connector of PS it still made the noise but didn't seem to be as bad.

The other thing I noticed is that even with the bottom connector unplugged the monitor still came up for a few seconds and then when black. About 10-15 seconds later it would come back on. After that it didn't come up anymore for at least the 3 mins or so I waited. If I turn it off and then back on it comes up again but this time for a very short period of time before going black.

Sounds like to me it is two seperate problems. Ideas?

[budm]

Re: Samsung SyncMaster 2443BWX Comes Up, Goes Down and On and On

All the lamps will have to be connected, otherwise the open lamp connection detector will kick in and shut down the inverter circuits. It seems to me you are hearing the arcing noise from the lamps due to burnt or poor connections at the lamps's end.

[Rtech]

Re: Samsung SyncMaster 2443BWX Comes Up, Goes Down and On and On

All you need to do is turn the screen over....you do NOT need to plug in the connector from the Logic board to the screen,,,just the lamps,,the image is not causing the problem,,just the lamps I suggest.

[Stingray75]

Re: Samsung SyncMaster 2443BWX Comes Up, Goes Down and On and On

OK I will try it. But what about the small connector going to the front panel controls? Will the screen turn on without that connected?

Also, I have a bad SyncMaster 245BW taken apart right now. Is the screen the same? Can I use it for ops check?

With those connectors off what reaction from the monitor am I looking for? Thanks for your help guys.

[Stingray75]

Re: Samsung SyncMaster 2443BWX Comes Up, Goes Down and On and On



I answered some of my own questions above. I found out that it is very easy to lift the frame off the monitor and configure the test set up so that the front panel controls will reach the connection on the power supply. As you can see from the pic the two connections are reversed now. Symptoms are exactly the same. The arcing sound in the bottom right of the screen is still there or atleast it was the first couple of times I powered it up. It doesn't do it everytime. With the logic board disconnected the entire screen lights up for two seconds and then goes black. A little while later it lights up again and goes down.

[Stingray75]

Re: Samsung SyncMaster 2443BWX 2 Seconds to Black Times Two

This title makes more sense.

[budm]

Re: Samsung SyncMaster 2443BWX Comes Up, Goes Down and On and On

You should have it hook up to running PC so it will not go into standby mode due to lack of video signals.

[Stingray75]

Re: Samsung SyncMaster 2443BWX Comes Up, Goes Down and On and On

OK, I have VGA connected now. Still two seconds to black but now everytime I change the video mode on the laptop the backlights come back on and it does two seconds to black again. IAW turning the video off and back on again makes it go through another two seconds to black cycle without turning the power off.

[Rtech]

Re: Samsung SyncMaster 2443BWX Comes Up, Goes Down and On and On

swap the screen for the other one you have, and see what happens ??