television malfunction mystery

[jon]

Hello-

I have an 8 or 9 year old Magnavox television that has a very
conditional problem. During the daytime, the picture is great, but when
it is dark outside, not just dark inside, the picture gets interferance
in the top 1/3 of the screen, in the shape of a thick black line that is
shaped like an arrowhead, that jumps from the left side of the screen to
the right. Anyone have a theory?

Thanx, Todd

 

[Jackson]

Hello-

I have an 8 or 9 year old Magnavox television that has a very
conditional problem. During the daytime, the picture is great, but when
it is dark outside, not just dark inside, the picture gets interferance
in the top 1/3 of the screen, in the shape of a thick black line that is
shaped like an arrowhead, that jumps from the left side of the screen to
the right. Anyone have a theory?

Thanx, Todd

Just a guess: Maybe a ham radio operator in the neighborhood, or
somebody fires up an electrical device at dusk that is emitting
interference. Lots of stuff are on photoelectric switches and come on
automatically at dusk.

 

[kb1lko]

Hello-

I have an 8 or 9 year old Magnavox television that has a very
conditional problem. During the daytime, the picture is great, but when
it is dark outside, not just dark inside, the picture gets interferance

Sodium Flood lights?

 

[Dick]

Hello-

I have an 8 or 9 year old Magnavox television that has a very
conditional problem. During the daytime, the picture is great, but when
it is dark outside, not just dark inside, the picture gets interferance
in the top 1/3 of the screen, in the shape of a thick black line that is
shaped like an arrowhead, that jumps from the left side of the screen to
the right. Anyone have a theory?

Thanx, Todd

Look for things that come ON at dusk...street lights, yard lights,
night lights, perimeter fences, etc.
The interefernce you describe appears to be 1/3 of a frame (180 Hz),
frame rate is near 60 Hz.
Amateur radio interference (ok, CBs n/ cabs too) would occur at an
audio rate, and would affect the entrie video and/or audio signal.