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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: laxiton on March 31, 2011, 11:43:41 AM

Title: Amiga RGB to SCART, weird image
Post by: laxiton on March 31, 2011, 11:43:41 AM

Hello everyone!
 
I've taken new interest in my good old A1200. I first connected it via AV cable to my Samsung Series 6 LCD TV. Then started looking for other, better connections.
 
Found an RGB to SCART cable. I have two SCART connections at the back of the TV. One says AV and the other says RGB.
 
I tried both, first (AV) gave grey screen which is normal I guess but the RGB one doesn't work correct either. When plugged there's a mainly grey screen with some weird effect on the image, you can see slightly what's there as some kind of Bevelled/Embossed image type of effect shining through. But just shades of grey, no colours or clear picture.
 
What's wrong? What can I do?

Title: Re: Amiga RGB to SCART, weird image
Post by: alexh on March 31, 2011, 11:54:31 AM

You need a correctly wired SCART cable.

When TV's were CRT based (analog) the voltages on the wires directly drove the electronics which produced the picture. If they were slightly wrong (voltage level wise) it didn't really matter, you still got a picture.

Now LCD TV's are digital and the SCART inputs are sampled and converted to digital and then put through a video decoder to produce the picture. If the analog inputs are out of spec then the sampler and video decoders don't (always) work.

Your RGB SCART cable needs to be fully wired. It needs to have the right voltage on the CSYNC, BLANK & AVSEL pins.

You can either get a new guaranteed to be fully wired SCART cable for £17 from AmigaKit

http://amigakit.leamancomputing.com/catalog/product_info.php?products_id=226

OR you can try to make your existing one compatible. Notice all the ground connections and the values for the resistors. (Ignore the optional composite connector)

(http://www.ianstedman.co.uk/downloads/SCART_cable.png)

Title: Re: Amiga RGB to SCART, weird image
Post by: Amiga_Nut on March 31, 2011, 01:29:39 PM

You also have 'Sony SCART' and 'Other SCART' and a non Sony SCART wired up cable plugged into a Sony TV would not work and VICE versa, e.g. the one used with the Philips/Commodore monitors which had SCART sockets.

(you can laugh if you like but I still have two types of cable for two different CRT SCART TVs :) )