Pretty common problem with TVs/monitors is the power supply capacitors. If you unplug the monitor and are able to open one up, look at the capacitors on the printed circuit board(pcb). If the tops are bulged - they will need to be replaced. Here is what they look like for example: http://www.digikey.ca/product-detail/en/EEA-GA1C220B/P15790TB-ND/2513292. If you find bad ones I can help you pick out replacements. I'm an electronic tech with 30 years experience.
-Bruce