Why does the B&S CMM light pen not work with an amber CRT?

[Bill in PA]

B&S MicroVal CMM

The current CRT has a blue and white display. I bought an amber CRT as a spare. The amber display is crisp and bright but the light pen does not work with it. Anyone know why? I was hoping to use the amber one as the other CRT cuts off part of the display.

Thanks,

Bill

 

[Scottl]

It may well be that the sensor in the pen will not respond to that wavelength or it could be a filter in front of the sensor causing the issue. Either way, not generally a quick and easy fix available.

 

[Gordon Heaton]

Should be relatively easy to adjust the current monitor to display the whole screen.

 

[Bill in PA]

It may well be that the sensor in the pen will not respond to that wavelength or it could be a filter in front of the sensor causing the issue. Either way, not generally a quick and easy fix available.

It does have an anti-glare screen.

Bill

 

[Scottl]

It does have an anti-glare screen.

Bill

I suspect it's more likely the wavelength of the light. Amber is more yellow whereas white contains all colors.

Possibly there is a contrast adjustment somewhere for the pen that could be tweaked. Are there any user groups for these machines?

As Gordon suggested, 1st solution would be to adjust the current monitor. I'm assuming this is an analog monitor and they always have adjustments for screen size and position.

 

[Bill in PA]

I suspect it's more likely the wavelength of the light. Amber is more yellow whereas white contains all colors.

Possibly there is a contrast adjustment somewhere for the pen that could be tweaked. Are there any user groups for these machines?

As Gordon suggested, 1st solution would be to adjust the current monitor. I'm assuming this is an analog monitor and they always have adjustments for screen size and position.

The amber monitor is EGA and displays correctly. I believe the other monitor is CGA. It cuts off the additional horizontal lines. The width cannot be corrected enough too.

The light pen works with the CGA monitor switched to green also.

I'll have to keep looking for an EGA monitor that is not amber.

Thanks,

Bill

 

[Bill in PA]

Tried an XVGA box and a VGA monitor. Screen displays correctly but the light pen does not work. Arrgh.

Bill

 

[SeikiCorp]

The 'speed' of the phosphor coating might be changing the signal enough the pen cannot get a reliable reading.

It is the micro-seconds delay that allow it to track where you are on the CRT.
So much time puts you at X on the screen, longer time puts you at Y position.

CGA, EGA, VGA, SVGA all have different sync and refresh rates. Adding the XVGA converter which is a frame buffer device, just makes more timing issues.

 

[CarbideBob]

Tis how the old light pens work.
You can not switch between CGA and EGA.
Even though you see it fine the pen will not trigger at the right time so it is lost in space.
The pen not only needs some light it needs it at the right timing of the scan.
Agree it is possible to be color sensitive or not enough light but more likely a scan time problem.

 

[Bill in PA]

Tis how the old light pens work.
You can not switch between CGA and EGA.
Even though you see it fine the pen will not trigger at the right time so it is lost in space.
The pen not only needs some light it needs it at the right timing of the scan.
Agree it is possible to be color sensitive or not enough light but more likely a scan time problem.

The CMM does not display correctly on a CGA monitor. Some of the lines are cut off at the top and bottom as well as the width being too narrow. This cannot be corrected for with adjustments. I thought that the display signal was EGA, but the XVGA adapter displayed an horizontal frequency of 18 khz (same as MDA). Perhaps I actually need an MDA compatible monitor.

The CGA monitor works well enough to use the CMM, but I would like to find the correct monitor.

Bill