Laurie:

There are really several possible problems you may be encountering.
Positioning is one, another may be gain...

Beam finder centers the display so you can see you have a trace active. In
most models, it also temporarily switches the scope to auto trigger.

Most likely, you have the horizontal or vertical position maladjusted to put
the display way off the screen... Try centering the horizontal and vertical
position controls and see if you can see the trace.

If you set the trigger to Auto, you should see a trace on the display even if
there is no signal applied. Also, when you press the beam finder, if you
watch closely, you may notice which direction the displayed waveform came
from, or the direction it goes when you release the beam finder button. This
can give you an idea of which of the position controls you need to adjust.

If you have the position controls centered and the trace isn't somewhere near
center, check the DC/AC signal switch. If you have it set to AC, it should
be centered if the display position controls are somewhere near centered. If
the input signal is DC coupled, and there is a significant DC offset to the
signal, it can be off screen. Changing the coupling to AC will help to center
the trace on the display.

Gain could also be a problem. If you have the vertical gain set too high,
even if the display is centered, the trace is spread out so far vertically
that it can be nearly invisible.

Still no joy?
To set the scope to a known state, set Coupling to AC, center the horizontal
position controls, and set the trigger to auto. Turn up the display
brightness (not the graticule illumination) and you should see a single
horizontal line (trace) somewhere near the vertical center of the display.
Add an input signal and you should see a change in the trace. Adjusting the
time base and trigger level should allow resolving the trace to a
stable display.

Nearly everyone has lost a trace in the history of their scope use, been
there, done that myself a time or two, especially when in a hurry....

--Rick AH7H

Laurie Landry wrote:

My Tek 466 scope decided to misbehave. It will not display the horizontal
beam unless I press the beam finder. When I do it displays whatever I'm
looking at(eg: 7 Mhz sine wave) properly.
I'm quite familiar with this scope, but possibly doing something stupid.
Does anyone have any idea as to what the problem could be?
Thanks in advance for any light you can shed on the problem.

Laurie