tv SONY KV-B2513E PICTURE INTERMITENT

[xAvi]

Hello to everybody, first of all sorry for my english. I have a tv model kv-b2513e, i think its a AE2 chassis. the problem its the next:

the picture appear and disappear continusly for a 1 or 2 seconds,
the sound its ok, the picture its very darkness, its like no quality contrast. i´m technician and i try to adjust the Voltage screen G2 and the picture can stay(without disappear) all the time, but with a poor quality of contrast and colors, its very strange. I suspect that any protection circuit its working, and dont show the picture when this cirucuit its working. i look all the voltages and are ok, i suspect that the problem its in the Vg2 voltage or the crt?

thanks to all

REgards XAvier