composite to vga adaptor

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fridgemagnet
Posts: 89
Joined: Mon Nov 24, 2014 8:33 pm

composite to vga adaptor

Post by fridgemagnet »

Hi all,

I bought one ofthese composite video to VGA adaptors with the purpose of hooking up my Dragon to a standard monitor (at the moment I'm reduced to using an old portable TV in the back bedroom). Unfortunately it's giving me an effect as shown:
Dsc01385.jpg
Dsc01385.jpg (128.18 KiB) Viewed 1760 times
the purple lines scroll down nicely. I get a similar (though less noticeable effect) connecting up the o/p of an old video recorder to it but it all works fine when connected to the s-video (through a composite adaptor) o/p of my laptop. I did wonder if this was a PAL/NTSC type of thing but switching between the modes on the laptop all still looks good.

Just wondering if anyone else has had experience with this sort of thing and has any thoughts as to what could be causing this.

Rgs,

Jon.
sorchard
Posts: 530
Joined: Sat Jun 07, 2014 9:43 pm
Location: Norwich UK

Re: composite to vga adaptor

Post by sorchard »

Just a wild guess, but it could be that the converter is having trouble locking on to the colour burst frequency coming from the Dragon.

If so, then it might be worth adjusting the trim capacitor near the colour crystal in the Dragon to see if that helps. This trimmer provides a little adjustment of the colour frequency and is usually used to tune out the dot crawl.
Stew
fridgemagnet
Posts: 89
Joined: Mon Nov 24, 2014 8:33 pm

Re: composite to vga adaptor

Post by fridgemagnet »

Seems to improve things slightly adjusting the cap but it's still not that good. Suggestion I have from a chap at work is that the output from these somewhat older machines is probably a bit rough and ready and the adaptor is struggling to lock on however someone else has a composite to HDMI adaptor that works fine on a Spectrum so he's going to loan that to me, see if it works better with the Dragon.
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