What does a flickering screen indicate?

[azguy1878]

The set works good, picture comes in nice and clear..after a few minutes the screen starts to flicker...it gets brighter for a split secound then after about ten secounds does it agian..the picture doesnt cut out or roll..it simply gets brighter for that split secound! I guess flash would be a more proper word to use. Anyone know waht causes this?

[Tony V]

I'd check the video output tube first. What kind of tv is it?
-Tony

[azguy1878]

Thats a good idea...its a Predicta by the way...what other set would have more problems..LOL