Flash on the green light,i guess it could be a false contact

If you have an issue where your picture turns off and the green power light starts flashing, you are most likely looking at a weak or old lamp. Do not be confused with a pix loss and a RED light flashing, as this can be caused by many things. The normal sequence of events for this fix is this:
1) TV turns on normally, plays for 1 to 3 minutes (may be more or less time)
2) Picture goes out and green power light begins flashing. It may flash for up to 2 minutes
3) green light turns on solid (stops flashing) and picture returns.
4) Picture goes out again and process repeats.

You may have been told that "if the lamp light isn't on, it isn't a bad lamp".
FALSE!
A weak lamp will cause the process above to occur. Other signs of a weak lamp:
The reflector in the lamp is very cloudy
You may see a "growth" or "bubble" on the vertical glass tube which is the lamp
You haven't replaced the lamp in quite some time or it is the original lamp from when you purchased the TV.

In cases like these, try a new lamp. Stick with an original Sony lamp, as there are many stories (both personally witnessed by me and also documented on the web) about problems with after market replacement lamps. And remember, lamps DO NOT have a shelf life; you can store them in a good environment (not too hot or cold!) for an indefinite period with no ill effects.