Hello,
It's approaching that festive time of the year and I have been busy stringing many LEDs together
Will now try and address some of the recent comments.
With regard to pin 13/DGND, I covered most if it here:
http://eab.abime.net/showthread.php?...ing#post784306
I doubt it will make much difference how you ground it, but I always separate Analogue ground (Video) from Digital (CSYNC). It's not directly related to Signal Integrity, more EMC and good practice, from my friends at Analog Devices,
http://www.analog.com/static/importe...0Grounding.pdf
It may make a difference on the A500/A1000, but not on the other machines. The cable diagram is for all.
@shk
The 270-510 ohms, nominal 330 ohm, is just a potential divider. I want to ensure the signal seen by the TV is <1V. The TV has 75 ohms to ground, The Amiga 47 ohms and the cable 330 ohms, giving 377 ohms from the Amiga, as seen by the TV. Vout = 75/(75+377) x Vin.
in = 4.4V minimum, so vout is 0.73V minimum and 0.82V maximum.
Did adding the AC coupling capacitors improve the picture in any discernible way?
@bladecgn
Try the optional composite video to pin 20 of the SCART socket. This is the actual signal all TVs expect to see, not a sync signal.
Some TVs, 'alpha blend' the composite video with the RGB, to enhance the edges. The user has no control over this. If the composite signal is just that, it will work. The Amiga CSYNC TTL signal, when attenuated, will look like bright white video and could create sparkles/ghosting if blended. This needs some photographs to explain.
It is for that reason, the composite video plug has been shown on the diagram since 2009.
What are your contrast/brightness settings?
Brightness controls black level, contrast controls white level. For a TV, I typically use 50% brightness and 80% contrast, with a Broadcast standard monitor, I would use 0% brightness and 50% contrast.
@MrB
Sorry I missed your earlier post. The only LG TV I have is a 2010 19" widescreen, which is shown in a few photos in the thread.
Are you confident adapting the SCART cable to feed composite video to the SCART cable from the Amiga?
@thread
Part of the next stage of my website development is to write a retro video guide, which will detail some of the lessons learnt adapting various non-standard video signals to normal TV/monitor displays. This is intended to go alongside the often delayed, Retro Video Adapter I have in prototype development. The 240p/288p video issues have taken a bit of planning to work around, efforts are focused on this development stage before updating the website.
If I go quiet for a week or two, it's probably because I'll be cursing at Xilinx ISE/Isim or eating festive food and drink
