I have a Compaq TFT7020 17" monitor that I got last year from Dubai Plaza, Pindi (2nd hand).
For some days, it just turns off automatically and then sometimes turns on by itself. The LED showing power also goes off, means that power cuts off.
If it does not turn on by itself, then I unplug the power cable and replug it and it turns on, but the same thing happens again and again.
I don't think there is a problem with the adopter. Also, the power cable is okay, since I'm using that with the other monitor (old CRT) and it's working fine.
I also checked it by connecting to TV device and again had the same problem.