PAL VS NTSC on old B&W TV, does it matter?

[neazoi]

Hi I have a gear (old TV CW/RTTY encoder/decoder keyboard) that outputs NTSC video (only typed white letters, no audio, nothing else) to the tv.
I have also a cheap B&W CRT TV that has vertical frame adjustment pot. The TV is PAL, not NTSC like the keyboard.

Will I be able to use them together and display the white characters on the screen? Both systems are B&W.

 

[andre_luis]

At least the 'PAL-M' variant ( used in the country were I am ), it is fully compatible with previous B&W receptors. Not sure about others, but this one add the color information as a small burst at the horizontal blanking interval, which means that the original image is unaffected at all regardless transmited as color or back and white.

 

[neazoi]

At least the 'PAL-M' variant ( used in the country were I am ), it is fully compatible with previous B&W receptors. Not sure about others, but this one add the color information as a small burst at the horizontal blanking interval, which means that the original image is unaffected at all regardless transmited as color or back and white.

Brazil and Greece, seem to have used the same system https://en.wikipedia.org/wiki/NTSC#/media/File:PAL-NTSC-SECAM.svg
So you say that an NTSC B&W video signal, will work ok on both NTSC and PAL B&W TV sets?
I think PAL and NTSC do not have to do only with color but also with timing, am I wrong?

 

[BigBoss]

PAL and NTSC are not compatible in Horizontal and Vertical Lines. 525 vs 625 so picture will not be synchronized with video, and it will slide.

 

[andre_luis]

AFAIK, with NSTC transmitter we can recognize something on PAL receivers, but at the cost of quality of the video, sometimes extremally degraded. At least that's what I experienced on cassette players.

 

[neazoi]

AFAIK, with NSTC transmitter we can recognize something on PAL receivers, but at the cost of quality of the video, sometimes extremally degraded. At least that's what I experienced on cassette players.

Yes I remember that also. However the situation is different in this setup. The video generator is B&W and so is the TV used. The TV has vertical frames adjustment potentiometer, so in theory it should be able to provide a stable image and not vertically scrolling. NTSC had fewer lines, so in theory, on PAL TV, I should see at the top or at the bottom of the screen, the previous or next frame parts.
I do not understand BigBoss's "vertical lines", there are no vertical lines to my knowledge.

 

[BigBoss]

Yes I remember that also. However the situation is different in this setup. The video generator is B&W and so is the TV used. The TV has vertical frames adjustment potentiometer, so in theory it should be able to provide a stable image and not vertically scrolling. NTSC had fewer lines, so in theory, on PAL TV, I should see at the top or at the bottom of the screen, the previous or next frame parts.
I do not understand BigBoss's "vertical lines", there are no vertical lines to my knowledge.

"Vertical Lines" means Vertical Refresh Frequency. 50Hz vs 60Hz.
So even there is a little adjustment margin on both vertical and horizontal direction, I guess the picture will not be stable.
Note: Even some old B/W Television Video Processors may have an option to choose PAL/NTSC/SECAM standards. Check yours ..

 

[betwixt]

Having worked on both systems I would say 'try it and see'. The horizontal scan frequencies are different and the vertical scan frequencies are different but if they fall within the adjustment range of the timebase oscillators you should be in luck. There are other differences, mostly to do with the sync pulse widths during flyback which might cause poor lock but there is a good chance it will work. Obviously, anything to do with color is out of the question.

If the horizontal scan can be locked, check the EHT generator for overheating after a few minutes, the transformer is normally tuned by a capacitor to improve efficiency and driving it with a lower frequency might increase its current consumption.

Brian.

 

[andre_luis]

BigBoss mentioned an important aspect about 50/60Hz mains. The PLL of the local oscillator is referenced by the public mains frequency to generate the sync frequency, which means that it plays a fundamental role on the on video stability, so it should be checked in your case if both matches.

 

[neazoi]

I would proceed as betwixt Brian mentioned either way, but I wanted to see if it would do any good.
Else I am going to need an ntsc TV for it, or hook it up to more modern TVs that support both standards.

I wonder if a homebrew video monitor like this one https://danyk.cz/elmon_en.html could be used in both standards on B&W

 

[betwixt]

The homebrew monitor woould probably work but you would struggle to find a suitable power transformer and find it even harder to find an electrostatic deflected CRT of any reasonable size.

Brian.

 

[FvM]

The PLL of the local oscillator is referenced by the public mains frequency to generate the sync frequency, which means that it plays a fundamental role on the on video stability, so it should be checked in your case if both matches.

Although vertical frequency is related to the regional mains frequency (to avoid slow running interference patterns), it's always synced to video sync signal. Operating a legacy B/W analog TV on a different standard is usually possible, vertical frequency and size may need adjustment by respective pots.