here is the complete history:
the monitor was intermittently faulty, i.e it used to works then at times no display. when i restart my pc the image is back (not always), after further investigation i've noticed the card was also faulty. I've got it replaced-it was a Rage II AGP card. However i tested the monitor with another pc with a different card, at first it was ok but not for long. Actually when i power it on nothing is suspected i can see the led flash indicating no signal. But as soon as i connect the vga cable the led turns green but display is available. I took voltage readings before & after connection of the cable and noticed that the EHT section is switched off as during normal stand-by mode.