Build Your Own Arcade Controls Forum

Main => Monitor/Video Forum => Topic started by: AE35 on August 27, 2016, 05:31:51 pm

Title: 15kHz RGBHV to SCART - about to cry!
Post by: AE35 on August 27, 2016, 05:31:51 pm

Hi guys

I am trying to get my source, 15kHz RGBHV, to work with RGBS SCART. The former monitor, Wells-Gardner,
accepted TTL sync from the source, and I think one is negative and one is positive. I believe that SCART uses
negative sync(?).

I have tried building this circuit, which should make both sync negative and output negative. but the picture is not syncing.
I did lower the voltage to 1V using resistors.
http://www.geocities.ws/podernixie/htpc/vga2csync.gif (http://www.geocities.ws/podernixie/htpc/vga2csync.gif)

Can anyone advice me? I do not need amazing image quality, I just need okay sync and a stable image.

Thanks!

Title: Re: 15kHz RGBHV to SCART - about to cry!
Post by: SailorSat on August 28, 2016, 03:40:50 am

The most simple way seems to be a simple 74ls04 to negate the positive sync signal, and an 74ls86 to XOR both seperate syncs to a combined one.

*edit*
as the 74ls04 has 6 inverters, you could invert both syncs if needed.

Title: Re: 15kHz RGBHV to SCART - about to cry!
Post by: AE35 on August 28, 2016, 06:28:12 am

Thanks, that does sound like the right way. Since the output will be TTL, should I make voltage divider with two resistors
the get to 1v?

Thanks!

Title: Re: 15kHz RGBHV to SCART - about to cry!
Post by: AE35 on August 28, 2016, 04:15:06 pm

That didn't work either. Picture is not syncing. I have to---give up I think.