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could it be me or does my vectrex flicker too much?


B4D TEMP3R 303

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I've had my vectrex for awhile but only just actually got a cart for it I got andrew coleman's 72in1 muti cart and as soon as I start playing it I noticed a few things I never did with minestorm first the names of games were really small and picture was not centred I've now fixed that by adjusting the pots on the inside and by using the test cart game but another thing is the flicker yes I know the vectrex can flicker sometimes when there's a lot of stuff on screen but is it me or does mine flicker more coz berzerk seems to ficker a bit until I kill all the enemies then its stops but games like spinball and vecter vaders and some others flicker so much its unplayable do these games flicker as much for you guys or is there another pot I can adjust on the inside to stop it a little ?

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  • 4 weeks later...

On my Vectrex the image is slightly out of alignment, and the lines don't always meet at 90 degree angles for games like Armor Attack, or Clean Sweep. Can this be easily adjusted if you open it? The image also seems to not be centered, because sometimes the overlays (such as Clean sweep and Armor Attack) don't match up good with the screen. You don't notice this without the overlays. Can this also be adjusted?

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More elements onscreen = longer / slower refresh.

 

A conventional raster monitor or tube CRT TV draws a horizontal line 262 (NTSC) or 312 (PAL) times per frame, at a scan rate of approximately 15khz. Amplitude modulation of the beam controlls the brightness.

 

Vectrex uses a vector display in which the beam rapidly draws multiple lines onscreen in a connect-the-dots fashion. There is no fixed refresh rate; instead the more objects the beam has to draw, the longer a frame takes to render.

 

So when many objects are shown onscreen, the frame rate drops resulting in screen flicker. Depending on the persistence of the phosphor image, lower frame rates can cause eye fatigue.

 

Basically the Vectrex is probably operating beyong the limits of human perception most of the time, then dipping the frame rate below a certain threshold at which you begin to notice the flicker effect. This is not unlike modern 3D systems which drop frame rates when too many polygons or special effects are drawn simultaneously, creating sluggish gameplay.

 

Back in the day I used to set my video card to refresh my monitor at 75Hz since 60Hz was bothersome to me. My mom's bedroom CRT is 50Hz tolerant although it chops the bottom edge off. I was playing that PAL TAZ game on my N64 Everdrive and it nearly made me ill. I don't know how Europeans and people in PcaL territories could stand the lower CRT refresh rates. Starting around 30Hz, the brain can discern individual pulses, and 15-20Hz can be seizure-inducing. 18Hz is right about the golden frequency that triggers an epilectic response. Strobes at around this frequency make me see purple spots for some reason, possibly an artifact of the optic nerve.

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