PC to RGB SCART CABLE DILEMMA

[shaffy]

Hi Folks, I've made that magic 15pin vga to euro scart cable, and believe it or not..... it works...well to a degree.
I can see the picture alright, but the vertical synch seems to be way off.  colours are great, horiz freq is ok, no rolling side to side, but the vertical rlling is terrible.
I use the schematics from http://www.jayma.org/mamescart/
but I've had a look at another website which suggests a slightly differenct approach to wiring the Vsynch and Hsynch...heres the address
http://www.idiots.org.uk/vga_rgb_scart/
If anyone knows what I'm doing wrong then please feel free to let me know : ]
else I'll be trying the idiots.org wiring method.
I'll be posting some shots --tomorrow is too many letters to type so instead I'll just say the day after today-- for evryone to have a good look.
bye folks
shaf

[Serpent]

Are you using an ArcadeVGA? I've also followed the schematics from http://www.jayma.org/mamescart/ and it works perfect with my ArcadeVGA.

[shaffy]

DOH !...sorry folks, I'm not using an arcade VGA card, I was trying to avoi any additional expenditure, but if its the case that it works perfectly with the arcade VGA card, then WAHOOOOO...I'll be ordering mine asap.
Whats input and output does the arcadeVGA accept, and does it support dual monitor output ?
I'll have a wander over to their site asap, to read some more on it.
How long does it take orders to arrive within the UK ?

[b3atmania]

I would not use schematics from that site. You cannot make composite sync by just soldering two sync wires together! Sure, it works for some people. Fact is that you are running signals outside their official specs and may well damage your monitor!

For some reason that site keeps coming up. If you want to create composite sync signal that is safe you must small build a circuit like this one.

[Minwah]

I would not use schematics from that site. You cannot make composite sync by just soldering two sync wires together! Sure, it works for some people. Fact is that you are running signals outside their official specs and may well damage your monitor!

For some reason that site keeps coming up. If you want to create composite sync signal that is safe you must small build a circuit like this one.

Well I believe joining the sync's together is perfectly fine for use with an ArcadeVGA and Scart.  Using a non-AVGA card tho is a different matter...

[Sune_S]

I would not use schematics from that site. You cannot make composite sync by just soldering two sync wires together! Sure, it works for some people. Fact is that you are running signals outside their official specs and may well damage your monitor!

For some reason that site keeps coming up. If you want to create composite sync signal that is safe you must small build a circuit like this one.

ATI cards (i guess this means the arcadevga too?) can output composite sync through such a cable if you connect VGA pin 10 (sync ground) & pin 13 (horizontal sync) to SCART pin 20 (composite sync) & pin 17 (composite sync ground).

This works with Powerstrip and the ATI windows driver (you can select composite sync),I don't know if it works with AdvanceMAME...But i'll find out!

-Sune

[AndyWarne]

I would not use schematics from that site. You cannot make composite sync by just soldering two sync wires together! Sure, it works for some people. Fact is that you are running signals outside their official specs and may well damage your monitor!

For some reason that site keeps coming up. If you want to create composite sync signal that is safe you must small build a circuit like this one.

You don't really need this. It is fine to connect H and V together. On some cards this doesnt work (but won't cause damage) because some resolutions produce a mixture of positive and negative sync polarities. The ArcadeVGA card always sends negative vertical and horizontal sync at all resolutions. On other cards, you might be able to flip the polarity in the driver so they are both negative.