A line running through the pix is almost always a
bad filter cap. Usually there is also a hum. One line
is 60 hz, 2 lines are 120 hz. You need a full wave power
supply to give 2 lines.
Other thing is rare. A tube with H-K leakage.
Third thing is interference from another piece of gear.
Check your work then try "jumping" or "bridging" the
electrolytics. More on that if you need it.
73 Zeno
