Amiga RGB - SCART cable - How to wire it?

[twizzle]

http://www.avishowtech.com/mbhp/res.html

here is the site to find out your resistor values

the 1 that skippy is using is 100hms +/-5%

[alexh]

It doesn't matter which pin you use (12v or 5v) as long as your resistor value is correct.

To be honest I've never trusted ANY of the resistor values on ANY of the accredited Amiga->SCART diagrams.

Most diagrams recommend connecting pin 8 to 12v via 1K ohm resistor in-series. How on earth that makes a voltage of between 9.5v and 12v I dunno.

Most diagrams recommend connecting pin 6 to 12v via a 150 ohms in-series. How on earth that can make the voltage between 1-3v, especially as it uses a lower resistor value to that above!!

If anything I would have thought the resistor values are the wrong way round!?!

[mingle]

@twizzle,

Thanks for the info... I managed to contact skippy and he was kind enough to send me a rough schematic and even made a short video to explain things - how helpful can you get!

@alexh,

I know what you mean - the conflicting/confusing resistor values had me scratching my head.

I went with skippy's diagram, which has a 100ohm resistor on pin 16 of the SCART plug (+5v from the Amiga's pin 23) and it also has a 100ohm resistor on the CSYNC pin of the SCART plug (pin 20).

I've just wired up my cable (thanks again skippy!) and it works pretty well, although there is some blurriness and 'ghosting' next to vertical sides of letters, window frames, etc - see the following cropped images:

















Not sure if this is just the result of the image-scaling, something to do with grounds/earth, the extra 100ohm resistor on pin 20 or just par for the course with LCDs?

I've also connected the internal cable shielding at both the Amiga and SCART eds of the cable...

Cheers,

Mike.

[Framiga]

that 100 ohm resistor to the CSYNC have no sence IMHO.

Secondly, are yours R G B and CSync wires shielded? how long the cable is?

anyway LCD are crap at that low Horizontal frequencies (above all if you have always used CRT in the past)

[Skippy]

I think from a purists point of view you could argue some extremely mild ghosting. But I think you need to keep in mind that the Amiga's RGB is very basic and that you are using an LCD TV as a monitor.

I don't really understand what absolute level of clarity you're hoping to achieve given the combination of equipment. It's not as though you've plugged some Nvidia Geforce effort into a High Def LCD monitor.

You may also experience a "rastering" line effect on motion, IE: mouse movement or scroller.
http://www.lumalaser.com/images/samples/Graphics-RasterGirl-large.jpg

With Amiga RGB to LCD.

Le Bush Kangaroo.

Have any of you other dweebs actually posted any valid schematics or comments? No, simple hypothised theories.
Just posting for the sake of incrementing your babble points counters. - heh. That's gonna go down really well - lol.
 :crazy:

[mingle]

@Framiga,

I tried without the resistor on pin 20 and it made no difference... Perhaps it's need for some TVs/monitors?

The cable I'm using is about 1.7m long and is shielded. I'm also using individual grounds for the RGB lines.

@skippy,

Thanks again for the help - I have a working cable now. It's just that I expected the picture to be a bit sharper/clearer. But you're right; it's an old machine on a new screen, so I shouldn't expect perfection! :-)

Cheers,

Mike.

[Skippy]

Excellent, delivered the facts with no nonsensical drivel unlike the other pretentious postings to this thread.

Praise be to me, thanks to the Lord for blessing me with superior intelligence.  :lol:

SkippyFox. 'Real Amiga User'  :juggler: