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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: mojo1999 on November 30, 2010, 08:48:57 PM
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Hi
I’ve been trying to make a RGB scart cable in an attempt to get a better output on my LCD TV.
I purchased a cable from ebay, this resulted in a black screen on my 37in samsung LCD tv.
I open the cable and added the resistors as stated in http://www.ianstedman.co.uk/Amiga/amiga_hacks/Amiga_SCART/amiga_scart.html (http://www.ianstedman.co.uk/Amiga/amiga_hacks/Amiga_SCART/amiga_scart.html)
The cable now gives me a display, however the screen is of a very poor quality. There seems to be a waving/ flicker and the blacks are very grey.
Is there anything else I can try to gain a better image?
Many thanks
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It almost sounds like to me your only getting a composite picture on your TV. At the scart end of the cable on pin 16 you should need 1 to 3v that tell the TV to switch to RGB Mode, maybe best to check the cable to make sure the voltage on Pin 16 is in this range.
Other than that it could be just a poor quality cable and not enough shielding. It's hard to say what exactly the problem could be as a lot of LCD TV's can for different reasons be quite tricky to get them to display an Amiga picture well, if at all... :(
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i've cut the composite input and measured the voltage on the blanking pin, its showing 3.6 volts DC using a 75 ohm resistor.
The cable should now only be using the RGB inputs. Are the video grounds linked? Is the logic ground required?
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Could you give me the exact model number of the Samsung your using and I'll try to find out the exact specs it has and hopefully be able to help you solve this problem... :)
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its the samsung Le37m87bd
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ok. gonna see what I can find...
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Gawd thats a big manual... :)
Didn't actually help much though, only bit of useful info in it was that It doesn't support interlace mode, but that shouldn't affect the picture on bootup as the initial screen should be Med-res (640x256).
I've only seen this problem with an Elion DVD recorder I have, much the same picture quality and disturbances you describe here. The (almost !) solution to that was placing 75ohm resistors directly from each of the Red, Green and Blue signals directly to ground. It improved the picture greatly but there were still some annoying flicker left over. The Amiga's RGB signal it gives out is quite a strong signal and for a few TVs and DVD recorders the placing of the 75ohm resisters usually clears up this problem.
However I don't know your skills with a soldering iron or making up cables/connectors but other than giving the above a try I don't think I can be of much more help here...sorry.... :(
As I mentioned it improved the quality greatly on the Elion DVD recorder and upon further investigation inside the machine, I found that anything going through the scart socket was being processed first by a small circuit board, upon tracing the input signals I eventually bypassed this board and this resulted in a perfect RGB picture, but I don't think you want to go dismantling your telly in the hope that you could do the same with it... :)
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Franko, What chips are on that RGB-input-board?
(trying to understand the mechanism at work)
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Thanks for the help.
I should be able to mod the cable. So is it 75 ohm from Red input to red ground etc?
again many thanks