Well i was not expecting to be in the same situation as i was a few days ago but at least this time i witnessed the decline before i lost the Target signal /
I think its one of the preamp Transistors i will pull out the preamp and test it as before tomorrow ,pretty much at the start i had very good results images and slowly i noticed the target image became blurry and and then slowly the Target image signal disappeared .
I tested the voltages and deflection all this is the same looks fine ,I sort of wish i wrote down the adjustments before this happened a mistake i will not do again .
Just when i was ready to do some tests and recordings arrr nothing go's to plan
Klaas Robers wrote:Vidicons have no grain, the layer is continuous. But they may have blemishes, spickels and/or unequal dark current (that is wat you see in total darkness, with the hood on the lens) on the target. The sharpness, definition, is almost always good enough for 625 lines.
I would not be able to see this yet as i am only trying 32 and when i can 64 lines so far but i will look out for it on the higher line rates .
When a vidicon is looking at a fixed picture for a long time (days, weeks, months) the picture may be "burned" in the target. That is thee dark current in which you still see the previous picture. This is when a vidicon camera is used in a fixed position for surveyance. This disappears slowly (days, weeks, months) when the vidicon is used under changing conditions, or aimed fixed at a white area. So old, used vidicons can have quite some imperfections.
I noticed the ghosting effect with an 80's camera i used to have ,i don't like the idea of doing that to the camera but see its a problem the old vidicon tube has ,i am glad to hear some times you can rid the Target of the burnt in image ...i know just instant pointing it at the sun its on there for good .
So yes i have noticed it too Steve and klass
And don't forget, you have TWO focus controls,
- one is the optical focus of the lens onto the target,
- two is the electron beam sharpness adjusted by the current in the focus coil.
Both should be well adjusted.... for 625 lines.
My tube has electrostatic as well as the other 2 but i see the magnetic focusing is more effective seeing it working .
Vidicons are not linear, they have a kind of automatic gamma correction. Thsi is contrary to the plumbicons, which are linear. For a plumbicon camera you need a gamma correction circuit, for a vidicon used in the same camera you can switch off the gamma correction.
Good luck!
[/quote]
Well that's good one less thing to think or worry about but now i am back to a little head scratching ,least by the end of this it will be able work out a problem quickly .