I do realize this is not the correct forum to post this in- as it should go under a different hardware category (for which there isn't one that fits). However, this is one of the very few public forums on this board and I definitely wanted this post to be indexed and able to be found by others facing this same situation- hence why it's living here.
We have a Samsung SA300 (22" version) in our shop that is showing the all to common issue with this model monitor- no video and/or the check signal message being displayed on the screen. The monitor was working fine previously- just decided it didn't want to work any more. If you search online you'll find this is becoming a common problem with this fairly new (manufactured July of 2011) monitor.
It's definitely a logic issue- and not anything to do with hardware or bad capacitors.
The fix is very easy- although nearly impossible to find. Even Samsung doesn't tell you what it takes to fix it- even though they are the ones tha provide the fix.
It's simply a firmware update. Just connect the monitor to a PC as a second display (otherwise you won't be able to 'see' the desktop and run the firmware update!). I used a laptop with a VGA out port to get the job done.
Go here and and scroll down to the Manuals & Downloads section then choose the Firmware option. Download and run the firmware updater.http://www.samsung.com/us/support/owners/product/LS22A300BS/ZA
Then, after it's finished installing, run the Samsung FirmwareUpdater app now located in your Start menu. Let it do it's thing. Once finished the monitor will shut off. Just turn it back on- bingo. Problem resolved.
I do believe this same firmware update utility works with the entire SA300 series of monitors.