ppppenguin
03-31-2012, 11:17 PM
The Aurora standards converters have been a great success, introducing many people to the joys of 405 line TV. Well over 500 converters have been sold. Not surprisingly the vast majority have been the SCRF405A model, to the UK for running 405 sets. This is followed by the 819 line version for old French sets. Very few other countries used 405 so only a few 405 sets have found their way outside the UK and Ireland. By the time Australia and New Zealand started their TV services 405 was on the way to obsolescence so they started on 625. Despite this a few 405 and dual standard sets have found their way to enthusiasts “down under”. Unfortunately this has exposed a little known problem concerning TV in the antipodes. (I love that word, especially when pronounced “antipoads” by Stanley Unwin) This is the problem of picture inversion.
First a little background. Actually it’s really putting the future before the past because it’s about colour TV. Colour CRTs are extremely sensitive to stray magnetic fields, hence all the shields and degaussing arrangements. The earth’s magnetic field cannot be neglected, with some early sets just changing the set from pointing north/south to east/west could cause visible purity and convergence errors. Moving a set from the northern to the southern hemisphere can also cause visible errors. In older colour sets the purity and convergence were adjusted by the installer so there wasn’t a problem. With later pre-converged CRTs they were available in northern and southern hemisphere versions. Now with flat panel displays there is of course no problem.
In the early days of TV in the antipodes it was found that reversing the vertical scan in both the cameras and receivers could give a noticeable improvement in picture quality. When interchanging programmes between northern and southern countries you got the occasional inversion error but the broadcasters were pretty good at getting it right. Unlike present day widescreen signalling which is frequently done wrong. But what about the poor old 405 line sets that have found their way down under? These were made without inversion facilities and are thus likely to display the picture upside down. The Aurora converter was never designed to cope with this problem. Hardly surprising since there are so few 405 sets in the antipodes. Hence it’s quite likely that these sets will, on occasion, display an inverted picture. The crude answer is a DPDT switch in the feed to the vertical scan coils but this means an unpleasant modification to the set and can often lead to geometry and centring errors as these settings are rarely the same for both polarities. A better solution was needed.
If you are one of that exclusive band of people who have a World Converter (I do wish Darryl had found a better name than WC-01) http://www.tech-retro.com/Aurora_Design/World_Converter.html there is no problem. A simple firmware upgrade can be done completely free of charge. The SCRF converter is a more difficult problem. It just doesn’t have the hardware resources needed to do the job. After much head scratching Darryl finally found a way to modify the hardware. The new model is called the SCRF405AA (the 2nd “A” is for Antipodean). It is only available to special order and there is a cost premium of $60 (US). It is switchable so that it can still function as a normal SCRF405A. Darryl is also considering a part exchange offer for your existing SCRF405A. This is still being discussed but is likely to be something like $100. Further details of the SCRF405AA can be found here on Darryl’s website: http://www.tech-retro.com/Aurora_Design/SC_Antipode.html
An odd thought occurred to me as I was finishing this note. Many of you will be aware of the role of the Parkes observatory in relaying pictures from Apollo 11. http://www.parkes.atnf.csiro.au/news_events/apollo11/ There were considerable difficulties that have been well explained on that website. One thing they didn’t mention was the inversion problem. It hardly mattered when the pictures were coming from outer space where “up” is not really defined but for pictures coming from the lunar surface they had to make sure they got it right. The world would have thought it strange to see Armstrong and Aldrin wandering about upside down.
First a little background. Actually it’s really putting the future before the past because it’s about colour TV. Colour CRTs are extremely sensitive to stray magnetic fields, hence all the shields and degaussing arrangements. The earth’s magnetic field cannot be neglected, with some early sets just changing the set from pointing north/south to east/west could cause visible purity and convergence errors. Moving a set from the northern to the southern hemisphere can also cause visible errors. In older colour sets the purity and convergence were adjusted by the installer so there wasn’t a problem. With later pre-converged CRTs they were available in northern and southern hemisphere versions. Now with flat panel displays there is of course no problem.
In the early days of TV in the antipodes it was found that reversing the vertical scan in both the cameras and receivers could give a noticeable improvement in picture quality. When interchanging programmes between northern and southern countries you got the occasional inversion error but the broadcasters were pretty good at getting it right. Unlike present day widescreen signalling which is frequently done wrong. But what about the poor old 405 line sets that have found their way down under? These were made without inversion facilities and are thus likely to display the picture upside down. The Aurora converter was never designed to cope with this problem. Hardly surprising since there are so few 405 sets in the antipodes. Hence it’s quite likely that these sets will, on occasion, display an inverted picture. The crude answer is a DPDT switch in the feed to the vertical scan coils but this means an unpleasant modification to the set and can often lead to geometry and centring errors as these settings are rarely the same for both polarities. A better solution was needed.
If you are one of that exclusive band of people who have a World Converter (I do wish Darryl had found a better name than WC-01) http://www.tech-retro.com/Aurora_Design/World_Converter.html there is no problem. A simple firmware upgrade can be done completely free of charge. The SCRF converter is a more difficult problem. It just doesn’t have the hardware resources needed to do the job. After much head scratching Darryl finally found a way to modify the hardware. The new model is called the SCRF405AA (the 2nd “A” is for Antipodean). It is only available to special order and there is a cost premium of $60 (US). It is switchable so that it can still function as a normal SCRF405A. Darryl is also considering a part exchange offer for your existing SCRF405A. This is still being discussed but is likely to be something like $100. Further details of the SCRF405AA can be found here on Darryl’s website: http://www.tech-retro.com/Aurora_Design/SC_Antipode.html
An odd thought occurred to me as I was finishing this note. Many of you will be aware of the role of the Parkes observatory in relaying pictures from Apollo 11. http://www.parkes.atnf.csiro.au/news_events/apollo11/ There were considerable difficulties that have been well explained on that website. One thing they didn’t mention was the inversion problem. It hardly mattered when the pictures were coming from outer space where “up” is not really defined but for pictures coming from the lunar surface they had to make sure they got it right. The world would have thought it strange to see Armstrong and Aldrin wandering about upside down.