Vector monitor question

Weasel

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Im trying to find a replacement for my 25 ' star wars cockpit monitor. This was posted on google groups. Is this true or false ??


Carl wrote:
> On Jun 22, 10:43 pm, James Sweet <[email protected]> wrote:
>> weasel wrote:
>>> As the title says. Anyone ???
>> Good luck finding a complete one.

>> Fortunately, the boards are the same for either size, and the 25" yoke
>> is the same as the WG 19" yoke. The tube is a standard 25" CRT as you'd
>> find in an older TV or raster monitor, so you can build one if you can
>> find all the bits.


> Has anyone documented this, in detail - building a 25" color vector
> from 19" amp or WG parts?


> Joey



There's not really anything to document aside from what I just posted.
If you can find a WG 6100 yoke, stick it on a 25" CRT, then mount the
CRT in the game and connect it up to the deflection and HV boards. Power
it up and align it as would be done with any color monitor tube
replacement. The manual for nearly any monitor will have the procedure.
 
Yes it's true.

No I have never done it, but I know of people who have.
 
I've never done this personally but that document leads people to believe they can go out and buy ANY 25" TV and it'll work which couldn't be any further from the truth. There's many factors involved. Pinout and impedance to name a few.
 
Resolution is determined by the chassis not the tube.

Wrong-o.

Physical resolution is determined by the shadow mask in the tube.

For rasters, the chassis may only draw a certain number of lines per frame and throw away vertical resolution, but we're talking vectors, which have (almost) arbitrary resolution on the chassis, and the image quality is determined by the mechanics of the tube.

Finer shadow mask = smaller phosphor dots = better resolution.
 
Wrong-o.

Physical resolution is determined by the shadow mask in the tube.

For rasters, the chassis may only draw a certain number of lines per frame and throw away vertical resolution, but we're talking vectors, which have (almost) arbitrary resolution on the chassis, and the image quality is determined by the mechanics of the tube.

Finer shadow mask = smaller phosphor dots = better resolution.


OK, I can accept that for vectors. I've never seen it but I really don't look that closely.



So, how does this swap described above look? I can't access the ionpool site from work. Did they need to locate a specific tube or is there a reduced quality in the display?
 
Just so you know, Randy at RAMControls has new 25" tubes listed on his site. I'm pretty sure they're not ready yet, but it may be worth calling him.

On the tube swap front, Chad from arcadecup.com has done this at least once before and could probably set you up. -Malcolm
 
That would be DAVE at RAM Controls... and I wouldn't hold my breath on the tubes from him... he's still trying to get the yokes out the door he announced 3 years+ ago...
 
Wrong-o.

Physical resolution is determined by the shadow mask in the tube.

For rasters, the chassis may only draw a certain number of lines per frame and throw away vertical resolution, but we're talking vectors, which have (almost) arbitrary resolution on the chassis, and the image quality is determined by the mechanics of the tube.

Finer shadow mask = smaller phosphor dots = better resolution.

While I am not dissagreeing with Mark, because he is technically right, there seems to be some confusion when discribing resolution for the sake of CRT's

Dot pitch and Scan/Refresh rate are two different things. CGA (15kHhz) and EGA (25.4kHz) are the scan/refresh rate. The scan and refresh rate are determined by the montior chassis, more specifically the RC time constant on the horizontal and vertical oscillator.

I too was worried about the dot pitch and if using a higher scan rate would affect the picture, so I was able to e-mail a design engineer. Here is what he had to say.

"The number of the holes in the mask and stripes in the aperture grill technically set the maximum resolution of the monitor. At lower resolutions the logical pixels simply cover more than one hole or slot. The logical pixels do not need to line up with the physical holes or slots nor is there any mechanism to do so.

At resolutions that exceed the number of holes or slots across the screen, logical pixels (electron beam size) no longer hit the phosphors accurately enough to guarantee constant colors or luminance. Some of the beam is intercepted by the mask structure. On monitors with lower horizontal dot / aperture pitch, more of the beam is intercepted by the mask. However an image will still be displayed and in practice will look OK."

But as Mark said, this is a vector, so chassis resolution doesn't matter.

Luke
 
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