Turn it on..fine for 15 min. then screen goes blank...(blue( and message no signal....

Hi, Try this, Unplug the unit for 30 min. and then try it again. all connections. This should set the machine to default.

Well, at least you got it sorted out and everything is working fine now.

I had the same problem. It appears to be due to a bad tv tuner. Turn on your computer and leave the coax unplugged. Leave it for a while (15-30 min). When you see "snow" on your screen, you will be able to use the source button to change to another input and see if you can get a signal. I am running my cable through a dvd recorder and using the AV input to watch tv. Also, my HDMI, component and RGB work fine. After thank don't try to access the TV source until you have had your tuner replaced.

When does the screen go blank? Also what do you have plugged into it this most likely just because your input signal may be set at to high a resolution or frequency. Once I have more information I can assist you further.
Thanks,
Lee

First try another signal input like a DVD player or other source, is the signal displayed ok? Then you have lost the signal on one input from whatever the device is.

You need to replace the surface mounted voltage regulator IC (small black square chip with a metal tab on one end, and two legs on the other end.) it is on the main board, right behind the signal input board. It's a BA09FP regulator IC, you can purchase this on mouser.com

it requires a bit of disassembly, but it is relatively easy to do. it is component number IC9C25. It could be bad, or just have bad connections . This IC supplies 9 volts to the terminal board. Try resolding it first.

you have bad capacitors in the power board inside the monitor replace these and the monitor will work fine

It sounds like you have a boot sector virus.

i have one too and it always turns itself off at least 15 times a day and a red light comes on at the back and the screen is blank. It hangs up on people half way through phone calls, and tells me i have messages wich i don't and comes up with blank messages which i can't delete!! Today it has done the exact same thing again but it has been frozen for over 3hours i have tried taking the battery out and nothing works :(