- CRT question - 7 Updates
| etpm@whidbey.com: Aug 21 04:47PM -0700 So I built a kit that uses an electrostatic deflection CRT for the display. It all turned out very well except the display is much more in focus on one side of the screen. The CRT I am using is a Russian 5LO38i. The Heater voltage for this CRT is 5.7 to 6.9 volts and I measure only 5.1 volts. I'm not sure how the voltage for the heater or how any of the other voltages might affect the sharpness. The specs for the Russian CRT has the first anode voltage at 550 volts max and the second anode voltage max at 1100 volts max. But I measure only 250 volts for each. Could this be why the focus is not even? Anyway, thanks for any help. Eric |
| Jeff Liebermann <jeffl@cruzio.com>: Aug 21 05:35PM -0700 > So I built a kit that uses an electrostatic deflection CRT for the >display. It all turned out very well except the display is much more >in focus on one side of the screen. Is there an astigmatism adjustment? That's what's usually used to tweak display for even focus. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
| tabbypurr@gmail.com: Aug 21 08:16PM -0700 > even? > Anyway, thanks for any help. > Eric Presumably the electrode voltages aren't staying the same as the thing sweeps across the screen. NT |
| Jeff Urban <jurb6006@gmail.com>: Aug 22 08:42AM -0700 On almost any element the wrong voltage should affect the whole screen pretty much equally. One exception would be Scheimflung but that is not what you describe. What I think is the drive to the deflection plates is not properly balanced. Also, guy from Poland was telling me how crappy Russian CRTs are, maybe it is just defective ? |
| etpm@whidbey.com: Aug 22 08:54AM -0700 On Wed, 21 Aug 2019 17:35:58 -0700, Jeff Liebermann <jeffl@cruzio.com> wrote: >>in focus on one side of the screen. >Is there an astigmatism adjustment? That's what's usually used to >tweak display for even focus. Yeah, there is an astigmatism adjustment. And I adjusted it along with the focus and brightness to get the sharpest spot. What is weird is that the display is sharpest on the left hand side of the screen and then it gets more out of focus on the right. This out of focus is gradual, with each number being a little more out of focus. Eric |
| etpm@whidbey.com: Aug 22 08:57AM -0700 >> Eric >Presumably the electrode voltages aren't staying the same as the thing sweeps across the screen. >NT Any idea why this voltage change would happen? And if the voltage was increased could the out of focus become less? I figure there must be some sort of maximum sharpness the CRT is capable of. If this sharpness is voltage dependant then maybe higher voltage will fix the problem? Eric |
| Jeff Liebermann <jeffl@cruzio.com>: Aug 22 09:02AM -0700 >>tweak display for even focus. >Yeah, there is an astigmatism adjustment. And I adjusted it along with >the focus and brightness to get the sharpest spot. Nope. That's not how astigmatism is suppose to be adjusted. It's done with a horizontal trace across the screen. You adjust the astigmatism knob so that the trace is consistent across the screen. If you just adjust for the best dot, you end up with the focus and astimatism controls fighting each other, especially since you can't see what's happening outside of the dot area. Try it using a line and see if it's any better. >then it gets more out of focus on the right. This out of focus is >gradual, with each number being a little more out of focus. >Eric Well, there might be a component failure, but let's play with the knobs a bit more first to see if things improve. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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