Might one mask the entire TV screen with a disk or mask slotted or a hole about where one would
expect the (*e-) trace (between 2^1/2 & 3^1/2 deflected electron trace spaces
below the electron trace) and use a photo sensor to detect
brightness differences?
Above the electron trace if you "reverse the polarity" Terry. :-)
Fred
Retired NASA Engineer and Experimenter 1st Class, Francis J. (Frank) Stenger wrote:
>
> Fred
>
>I had a little time between the cleaning chores
> to unsolder just the little red deflection
> lead from the card on the side of the tube.
> Eureka - now getting a beautiful horizontal line across
> center screen. I had to turn the "brightness" control
> all the way down to keep the intensity at a safe level
> for the phosphor. The line is really sharp and crisp!
> Much better than on a scope!
> The next chore will be to do some diagnostics on the
> vertical deflection coils - get their resistance, try to
> see if my DMM will measure the drive voltage across
> the circuit, etc. Then, I can come up with a small
> battery supply to put a variable DC across the vertical
> deflection coils.
>
> it looks like the vertical coils have,
> 3.5 ohms DC resistance.
> I drove them with 1.42 volts DC which put the trace
> just off the top edge of the screen.
> Using the red lead post as positive gave the upward
> deflection.
> Using ohms law, I figure with a 5 watt, 27.3 ohm resistor
> in series with the coils 3.5 ohms, I can just hook it across
> my 12.5 volt car battery for a long run.
> Tonight when it gets dark I'll give it a try and see what
> I can see. (Yes, I'll get my eyes dark adjusted first.)
> I'll try to pick a deflection that gives the least backglow
> so it will do minimum damage to our resolution.
>
> If you have the means you could do this:
> 1. Snip the two vertical drive wires (red and white)
> about in the middle so you can resolder them later.
> 2. If you have a battery box for a single 1.5 volt
> cell (bigger cell the better since it pulls almost 1/2 amp)
> you could just use a cell to get the trace just off the top
> of the screen. Make the red lead positive as above.
> Be sure to back the brightness all the way down first!
>
> Using the car battery I can drive the necessary 0.4 or so
> amp for a long test time. I have the power supply
> driving the TV set so I think this is the best way to do it.
>
>
> Well, if the ~ 3-electron-mass particles exist, Fred, I'm seeing
> no sign of them in our experiment.
> The experimental rig we designed is working just according to
> plan. The modified vertical deflection gives a neat horizontal line
> which can be deflected near the upper edge of the screen by
> driving it with about 1.35 to 1.4+ VDC. With the brightness
> turned all the way down, the trace is just about right.
> I was working with the trace about 3/8 inch from the top
> of the screen - I had covered it (as you suggested) with a strip
> of electrician's tape. This masked the electron trace very
> well, but - as I feared - the backlight from the trace lighting
> the rear sides of the tube gave a very faint background glow
> to the screen. You need not "dark adapt" your eyes for long
> before you realize that this unwanted glow will tend to limit
> the sensitivity.
> Still, I'll guess that I could have picked up a "rogue" trace even
> one thousandth the brightness of the main electron trace.
> No such trace could be detected (by me) after several minutes
> of screen watching.
> If I tried to boost the trace brightness, the result was just to
> increase the background light and it seems that this is a losing
> variation.
> As I mentioned earlier, You could probably duplicate this
> setup by doing no more than snipping the vertical leads and
> substituting a single 1.5 volt battery for the vertical drive.
> Come to think about it - a lower voltage nicad cell might be
> even better and would require no additional series resistance.
>
>
