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Not an assertion I would make!

I had one 7104 that had a permanently etched reverse image
of a square wave and a triangle wave... obviously from a
function generator.

I know that there is a large contingent of folks that own
these scopes, that have no real work for them, but seriously,
how long could you stand to view a square wave and a triangle
wave on your 7104's screen?

It boggles the imagination.... well mine anyway...

A more likely explanation is that the ebay seller had the
function generator traces on the screen, really really bright
because that is what 7104's are known for, and burned an image
in the screen while preparing for, and taking a photograph...
All staying within the protective timers very limited protection.

The amber limited viewing LED comes on whenever the image is
about what one would consider normal brightness for a 7904.
You have to have a pretty dim environment to be able to run
a 7104 comfortably, never activating that warning.

The 2467B does a much better job of protecting the MCP. It never
allows the readout to be on the screen continuously without a
trace being on the screen, without putting the readout into flicker
mode. It moves the readout around periodically to wear level the
readout area of the MCP. It limits the trace intensity to a
perceived value of screen brightness by strobing the intensity of
the beam hitting the MCP. It leaves the MCP at its lowest
amplification setting when the Intensity control is set to view
low performance images, only raising it when the Intensity control
is turned up near full... stuff like that.... In addition to the timers.

-Chuck Harris

Roy Thistle wrote: