phil@pepsi.amd.com (01/06/90)
I just compared a genuine IBM 8514 16" tube with a Seiko CM-1430 14"
tube under MS Windows' "terminal" application in both 640x480 and
1024x768 modes. The Seiko won both times. The Seiko was noticably
sharper than the IBM. Is this because it's a smaller tube? Perhaps.
All I know is, my eyes hurt after using the 8514 for a few hours, but
the Seiko doesn't bother me. The IBM also did not display a straight
raster in 1024x768 mode. The distortion was only about 1/4 inch but
certainly noticable and for a $1400 product, annoying.
All tests were done with an Orchid ProDesigner Plus.
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Phil Ngai, phil@diablo.amd.com {uunet,decwrl,ucbvax}!amdcad!philemmo@moncam.co.uk (Dave Emmerson) (01/11/90)
In article <28644@amdcad.AMD.COM|, phil@pepsi.amd.com writes: | I just compared a genuine IBM 8514 16" tube with a Seiko CM-1430 14" | tube under MS Windows' "terminal" application in both 640x480 and | 1024x768 modes. The Seiko won both times. The Seiko was noticably | sharper than the IBM. Is this because it's a smaller tube? Perhaps. | All I know is, my eyes hurt after using the 8514 for a few hours, but | the Seiko doesn't bother me. The IBM also did not display a straight | raster in 1024x768 mode. The distortion was only about 1/4 inch but | certainly noticable and for a $1400 product, annoying. | | All tests were done with an Orchid ProDesigner Plus. | That's probably not the CRT at fault, it's just badly set up. Any half-decent TV engineer should be able to fix it for you in no time - unless the tube's nearly croaked, and maybe even then if he has a 'tickler'. 'Unsharpness' is normal in an 'old' tube, especially if it's been used in black-on-white mostly. It's a shame more monitors don't have the focus control acessible from the outside of the case. BTW 'old' can mean anything from 6 months onwards. Quite often the focus pot itself either develops a bad spot, or goes 'high value'. They're usually cheap carbon presets costing just a few pennies. The distortion is usually due to sloppy placement of the correction magnets around the coil assembly, but it's often unnoticed when the monitor is generally only used for text. Some experimentation with these will often yield some improvement. More often, you'll find you need to add a few smaller ones to get it really square. If you decide to tweak the linearity coil, use the proper tool, anything else will ultimately break it! You may find that over-sharp focusing can be just as much of a strain as not-very-sharp. That's why Grundig used to sell so many TV's a few years back, a significant percentage *wanted* a 'soft' picture. (That was designed in, not bad focussing though). The contrast control can also affect the perceived sharpness of the picture, I hate monitors with only an on-off switch! (But I realise why the make them.) Avoid adjusting the 'Set Volts' pot unless you have a 20Kv EHT meter, or are into X-Rays. If the size is wrong, you should correct it by sliding the coil assembly on the tube neck. This also corrects 'tilt' if you rotate it around the neck a few degrees. None of this can be done with the back on, or the set switched off, so if you've any doubts, get a TV tech to call in and take a look, or learn to live with it. BTW it stands to reason that (in the same mode), a smaller tube will appear to give a sharper image when viewed from the same distance, if the quality is about the same. You should choose a size to suit your viewing distance, nothing else. Yes I do go on a bit don't I! OK OK I'm going! Dave.