Connecting an NMS 8250 to a HDTV using 50Hz output

Por Turrebo

Expert (77)

Imagen del Turrebo

24-09-2015, 14:22

I'm trying to connect my NMS 8250 to a Samsung LE40A552P3R tv using a SCART cable.
The only way I can get it to work is when I put the MSX in 60Hz mode with VDP(10)=0

If I don't do that, the picture is way too far off to the left. It also prevents me from playing ROM games.

I'd like to run my MSX at 50Hz, or, failing that, have the picture output at 60Hz and the rest of the MSX at 50Hz.

Any thoughts on that? Not afraid to handle the soldering iron.

[edit]
My tv can perform all kinds of tricks, but there's no option for 50Hz input compensation or anything like that... :-(

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Por bore

Expert (115)

Imagen del bore

24-09-2015, 14:47

Do you get the same problem with composite?

Por Turrebo

Expert (77)

Imagen del Turrebo

24-09-2015, 14:59

bore wrote:

Do you get the same problem with composite?

Strangely, no. Using composite in either 50 or 60Hz the picture is pig ugly, but centered correctly.

Por Grauw

Ascended (8612)

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24-09-2015, 15:02

How far to the left is it? You can tweak the horizontal position a little bit with SET ADJUST...

Por Turrebo

Expert (77)

Imagen del Turrebo

24-09-2015, 15:18

Grauw wrote:

How far to the left is it? You can tweak the horizontal position a little bit with SET ADJUST...

The screen is cut off at the left hand side. The word 'Color' (F1 key) is not visible.

I can adjust the view of my tv to display 4:3, 16:9, auto, and all kinds of zoom, but at best the picture is centered on tv (with black bars left and right), but still with a cut-off MSX screen.

When I put the MSX in 60Hz mode everything looks perfect. I'll give the SET ADJUST a try, though, I hadn't thought of that.

Por Grauw

Ascended (8612)

Imagen del Grauw

24-09-2015, 15:57

If the whole word COLOR is not visible, SET ADJUST is probably not going to help you (it can only adjust by 8 pixels to either side). Though maybe still worth giving it a try, changing it might alter the VDP beam timing a little, allowing the display to pick up the signal better... A long shot though.

Por Turrebo

Expert (77)

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24-09-2015, 16:03

Just tried it. It helps a bit, but not much. Unadjusted, 'Color' is partially visible, though. I think I may have exaggerated a bit (caused by blind fury most probably).
With set adjust (8,0) 'Color' is only just visible. Not nearly enough...

Por sd_snatcher

Prophet (3134)

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25-09-2015, 13:43

It might be an issue with the CSYNC signal. Try googling for a "sync cleaner" circuit, and build one yourself. It's pretty simple and only basic soldering skills are necessary.

Por Turrebo

Expert (77)

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26-09-2015, 22:42

Ok, I'll look into it. Thanks!

Por Wild_Penguin

Hero (573)

Imagen del Wild_Penguin

04-10-2015, 12:57

My 8250 has a similar issue, but not as severe. At 50Hz, the left part of the graphics is cut out (for example, in F1 spirit in the first selection screen, the green frame is not visible). But it is very much usable; for example, in text mode, I've never needed to use set adjust. Some games might miss some pixels (1-4) at 50Hz but they're still playable.

Since at 60Hz everything is perfect, I've thought the reason is the TV (I presumed they are sloppy at the factory, since these days most things is digital, so they made the analog video support bad and though nobody will notice). But if the sync cleaner fixes this, I might consider getting one, too. Let us know how it goes!