405 line 625 line vcr

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405 line 625 line vcr

Postby Harry Dalek » Fri Jul 14, 2017 10:24 pm

Found this link on the subject ...one day !
http://www.oldtechnology.net/using405tvs.html
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Re: 405 line 625 line vcr

Postby Dave Moll » Sat Jul 15, 2017 5:39 pm

Although most of the information on that page remains valid, it should be noted that this was written many years ago and does contain obsolete references.

there are people who advertise 625-405 line conversion services in the magazine "405-Alive", details of which are on the preceding page.


This magazine ceased publlication in 2001 and was incorporated into the Bulletin of the British Vintage Wireless Society.

When referring to digital standards converters, the one it mentions is the unfortunately-named Dinosaur. Like its saurian namesakes, this is now extinct. Examples of it, the Pineapple Converter and even the later Domino are now nearly impossible to obtain, although I do own a Domino, which I purchased for £400 when it was still in production. As far as I know, the only converter currently available is the Aurora by Darrly Hock in the USA. In the UK (if anyone else on this forum is based there) these have in the past been available from Crowthorne Tubes.

A review of the Aurora was written by Jeffrey Borinsky, who is a member of this forum.

I notice it mentions the possibility of recording 405-line material on Betamax or U-matic, but not having been tested. As I have examples of both of these recorders, I shall add to the "to-do list" getting examples of these up and running and to give it a try. Don't hold your breath, though - it's not something likely to happen any time soon.
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Re: 405 line 625 line vcr

Postby ppppenguin » Sun Jul 16, 2017 6:35 am

I've reviewed all of the 625 to 405 converters that were available in the UK. Also written several articles about the subject. All of these can be found on the "publications" page of my website: www.borinsky.co.uk

I can no longer see the point in recording 405 on a VHS or other video recorder except perhaps as an exercise. Yes, it works OK though tape dropouts are made worse by dropout compensators which assume lines are 64us long.

These days most people use an Aurora SCRF405A to feed 405 line sets. They just work superbly well. Some have had success with getting PCs to output 405 line signals. This is mainly based on work by Jim Beacon and Kat Manton. I've seen it working but it's a lot more effort than an Aurora. A few have had a go at making their own 625 to 405 convertors. It's not too hard for an electronics professional working with modern parts but a tough undertaking for an amateur. Most recently Frank from Ireland has had considerable success: http://golbornevintageradio.co.uk/forum ... p?tid=6193
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Re: 405 line 625 line vcr

Postby Harry Dalek » Sun Jul 16, 2017 9:36 am

Yes Dave and and ppppenguin it does interest me too and i did have a look at this my self as theres a few schematics floating about on the internet using so many parts that are no longer around or a night mare to track down it puts you off using them at least .

There are perhaps 3 other ways to get a vintage tv signal on 405 line first some one who has the systems converter could record it on a vcr tape for others now thats a good use for a vintage system would not make you rich but there would be those that have a vcr but no a systems converter.

The next way i am trying at the moment via a flying spot PMT camera make your own old school analog signal i am mainly working on line rates lower than 405 it must be simple as even i can work it out .

The 3rd way just a boring test card grey bars generator just to get a signal to the monitor

I will look into the links you have put up its interesting if only for a good read .
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Re: 405 line 625 line vcr

Postby ppppenguin » Mon Jul 17, 2017 4:52 am

Optical conversion works OK. Point a 405 camera at a 625 monitor. Not as good as electronic conversion but adequate. I've done it the other way round to recover 405 tapes where there isn't currently an electronic solution available off the shelf. Darius's analogue 625 to 405 converter was a remarkable piece of design, using CCD chips originally designed as 1 line delays for colour TVs. Bandwidth is limited and parts are hard to get. You'd want to be pretty dedicated to follow in his footsteps.

Experimenting is fine and good. Just to prove the point I've built a 625 to 405 converter using boards left over from a professional design job. Basically a decoder chip, FPGA, SDRAM and DAC. It works very well.

But if you just want to run your 405 sets with best possible picture quality then an Aurora is well worth the price.
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Re: 405 line 625 line vcr

Postby Harry Dalek » Mon Jul 17, 2017 10:27 pm

ppppenguin wrote:Optical conversion works OK. Point a 405 camera at a 625 monitor. Not as good as electronic conversion but adequate. I've done it the other way round to recover 405 tapes where there isn't currently an electronic solution available off the shelf. Darius's analogue 625 to 405 converter was a remarkable piece of design, using CCD chips originally designed as 1 line delays for colour TVs. Bandwidth is limited and parts are hard to get. You'd want to be pretty dedicated to follow in his footsteps.

Experimenting is fine and good. Just to prove the point I've built a 625 to 405 converter using boards left over from a professional design job. Basically a decoder chip, FPGA, SDRAM and DAC. It works very well.

But if you just want to run your 405 sets with best possible picture quality then an Aurora is well worth the price.


I am impressed by the work you have just mentioned you have done and vintage gos at the conversion ...money does buy every thing but can never buy personal satisfaction making one as i am sure you felt making yours ....
I recall seeing a photo in electronics Australia on a 70s 525 line 625 line converter for a tv station here must of been made all via transistors the case was the length and size of a wall .
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Re: 405 line 625 line vcr

Postby ppppenguin » Tue Jul 18, 2017 6:21 am

Harry Dalek wrote:I recall seeing a photo in electronics Australia on a 70s 525 line 625 line converter for a tv station here must of been made all via transistors the case was the length and size of a wall .


That would be the CO6/508 analogue field store converter designed by the BBC and made under licence by Pye. The prototype was ready just in time for he 1968 Mexico olympics when live coverage by satellite was feasible. Until then conversion between different field rates could only be done optically.

http://downloads.bbc.co.uk/rd/pubs/reports/1972-22.pdf

There's a photo of the beast in that report. I may have some other photos somewhere.The main stores were polygonal prism ultrasonic delay lines, like a PAL delay line on steroids. Some logic chips were used in the design. Probably RTL or DTL as TTL was very new indeed back then.

The main reason I built a 625 to 405 converter was just to prove the point. I'd been writing about the subject for some and felt I ought to prove that I could do it. Since I've designed standards converters before (relatively simple 625<>525) I had the tools and techniques readily available.
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Re: 405 line 625 line vcr

Postby Harry Dalek » Tue Jul 18, 2017 5:01 pm

ppppenguin wrote:That would be the CO6/508 analogue field store converter designed by the BBC and made under licence by Pye. The prototype was ready just in time for he 1968 Mexico olympics when live coverage by satellite was feasible. Until then conversion between different field rates could only be done optically.


That looks about right a night mare looks as bad as trying to make a a computer from transistors .
This is my 525 line to 625 line or visa versa converter which will do colour as well from the 90s use to do some tape trading and came in handy with my multi system vcrs .

There's a photo of the beast in that report. I may have some other photos somewhere.The main stores were polygonal prism ultrasonic delay lines, like a PAL delay line on steroids. Some logic chips were used in the design. Probably RTL or DTL as TTL was very new indeed back then.


It looks very complex amazing some one had to work out the circuits for that thing !

The main reason I built a 625 to 405 converter was just to prove the point. I'd been writing about the subject for some and felt I ought to prove that I could do it. Since I've designed standards converters before (relatively simple 625<>525) I had the tools and techniques readily available.


As the ic's become more complex this should become easier ? well beyond me but it does interest me i would for sure build one if i could at least i can copy circuits just a bummer the old designs used parts we don't have any more ///Hats off to you very impressive to be able to make one of those !
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Re: 405 line 625 line vcr

Postby Steve Anderson » Tue Jul 18, 2017 6:16 pm

Hmm, where in Australia might you get a 405-line TV? Unless someone unknowingly brought one into the country from the UK in the sixties. NZ had for short while a cable system that ran on 405, but I believe it was short-lived. It's not that easy getting a 405-line TV in the UK, elsewhere I would have thought nigh on impossible.

But given a monochrome 625 TV it's not that hard to 'adjust' the horizontal circuits to suit. The EHT might be the bug-bear though.

One of the small mom & pop corner shops here have a small (around 14") monochrome TV sitting on a shelf in the shop. It's covered in dust and I've never seen it switched on in 16 years. I've made noises that I may be interested in buying it, but to avail. I suspect they're hoarders. Who knows what upstairs looks like! I'm sure it'll need some work to get it going.

I was hoping to use it with the NBTV/SSTV-625 converter thereby negating the colour effects of the shadow-mask CRT on the TV I'm currently using. 14" or so is better suited to SSTV than 21" where you have to stand some distance away from it.

Karen Orton's favorite 5" mono TV's would be even better, but I have never seen one here.

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Re: 405 line 625 line vcr

Postby Harry Dalek » Tue Jul 18, 2017 10:42 pm

Steve Anderson wrote:Hmm, where in Australia might you get a 405-line TV? Unless someone unknowingly brought one into the country from the UK in the sixties. NZ had for short while a cable system that ran on 405, but I believe it was short-lived. It's not that easy getting a 405-line TV in the UK, elsewhere I would have thought nigh on impossible.


They did Steve in the late 1940's do trials of 405 line as i recall both Sydney and Melbourne did television trials one tried 405 line the other 625 line we know which one won out you would think any 405 line television is long gone by now.
Well it is on the want to do list one day just like to make one just for the hell of it more than likely with a small magnetic deflected tube from a 625 line small set ...one day :roll:

But given a monochrome 625 TV it's not that hard to 'adjust' the horizontal circuits to suit. The EHT might be the bug-bear though.


It would be nice to start from scratch ...I know the project i am on now has not got this standard but the flying spot scanner is a step for me just playing around with the signal source that could be if need be .

One of the small mom & pop corner shops here have a small (around 14") monochrome TV sitting on a shelf in the shop. It's covered in dust and I've never seen it switched on in 16 years. I've made noises that I may be interested in buying it, but to avail. I suspect they're hoarders. Who knows what upstairs looks like! I'm sure it'll need some work to get it going.


When i first moved to Melbourne there was a tv repair shop that a very old 6 inch screen tv in its window i tried to buy it with out any luck ,you get old tv's Steve from 1956 still about but they are all large screen no room for them ,makes me wonder what and where this was from we never had small screen tv's in the 50's all largish tubes

I was hoping to use it with the NBTV/SSTV-625 converter thereby negating the colour effects of the shadow-mask CRT on the TV I'm currently using. 14" or so is better suited to SSTV than 21" where you have to stand some distance away from it.


Smaller the better in this case there are still those tiny tv portables and old crt system small surveillance monitors may be they are harder to get these days in Asia ?
Karen Orton's favorite 5" mono TV's would be even better, but I have never seen one here.

Steve A.[/quote]

i come across them at the local tip shop time to time i can understand those being rare if you don't have a recycle shop i could look about if you want Steve next time i vist it .BTW what about something really small like a camcorder viewfinder tube monitor ,i have a 1 ich and smaller handy ...to small ?
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Re: 405 line 625 line vcr

Postby ppppenguin » Wed Jul 19, 2017 12:52 am

Harry Dalek wrote:As the ic's become more complex this should become easier ? well beyond me but it does interest me i would for sure build one if i could at least i can copy circuits just a bummer the old designs used parts we don't have any more ///Hats off to you very impressive to be able to make one of those !


Modern ICs help a lot.

At the input, analogue 625 video to 8 bit digits and clock in 1 chip with just a few odd passives. All sorts of low cost chips can do this. Started to become available in the early 1990s. I've used many of them over the years.

In the middle it's programmable logic that makes it all easy. At a guess I used few hundred lines of VHDL. Allows you to tinker with the design to your heart's content. Without even using a soldering iron.

The output has been easy for years as suitable DACs have been inexpensive for a long time. Or build a R-2R ladder DAC for next to nothing. It works fine if you're careful with the construction. The Aurora SCRF converters use a novel twist on the R-2R DAC to give 10 bit resolution with improved accuracy and reduced pin count on the programmable logic chip.

I don't know if any of the Antipodean members saw the April Fool spoof that Darryl (the Aurora man) and I ran a few years ago. Here it is for your amusement.

APRIL FOOL SPOOF 2012

405 line TV in Australia and New Zealand

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 ... erter.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 ... ipode.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.

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Re: 405 line 625 line vcr

Postby Harry Dalek » Wed Jul 19, 2017 10:45 am

HI Jeff
I don't know if any of the Antipodean members saw the April Fool spoof that Darryl (the Aurora man) and I ran a few years ago. Here it is for your amusement.


NO i had not seen that one ! why do we always get the upside down jokes we are on the positive pole which is up negative is down :D

I was thinking it would be getting easier with the ic's i have not seen any up to date circuits i was trying to follow the link on the new one being put together you were posting on its over my head but i am trying to follow .
Steve was is doing same sort of thing for SSTV and NBTV all very impressive ,,,may be i should in time give that a go least you get an understanding of the idea when you construct.
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Re: 405 line 625 line vcr

Postby Harry Dalek » Wed Jul 19, 2017 10:53 am

Steve i mentioned the small monitor ...if you want that ... to post up to you ,i think this is the one in my drawer either way working around that size ,if you what a touch larger CRT or monitor around the 5 inch i could come up with some thing there as well ..up to you least i could do with all the help tech help ! they are easy to get there the view finder ones less so but i always grab them when i see them .

youtu.be/FgHQADB3sTA
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: 405 line 625 line vcr

Postby ppppenguin » Wed Jul 19, 2017 6:02 pm

Harry Dalek wrote:HI Jeff
I don't know if any of the Antipodean members saw the April Fool spoof that Darryl (the Aurora man) and I ran a few years ago. Here it is for your amusement.


NO i had not seen that one ! why do we always get the upside down jokes we are on the positive pole which is up negative is down :D


That's because electrons flow in the opposite direction to conventional current :D
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