Sony 9-90UB TV - VHF Tuner 'Null' Position

[ppppenguin]

Francis, thanks for sending me the CVM90 manual by email. Since it didn't attach to your last post I've attached it here.

[peter scott]

Thanks to you both for the manual.

Peter

[Murphyv310]

Brilliant.
Thanks chaps.

[ppppenguin]

A note on using VHS machines to record 405.

A basic VHS machine knows nothing of the video signal at line rate. The luminance is simply modulated on to a carrier (FM) and laid down on slanting tracks. One track for each field. There's a disturbance between fields as one track ends and new one starts. This can often be seen at the bottom of the screen. The only circuit that knows about line rate is the dropout compensator. This stores a line of video in a delay line which repalces the current line if the signal from the tape is poor. The DOC will make a mess of 405 reply if the tape has many dropouts. Fortunately VHS tapes are usually pretty good.

Many later VHS machines have more complex signal processing which may mangle a 405 signal. The only way to find out is to try it.

Why did people record 405 on VHS machines? After 405 shutdown in 1985 the only people who had 405 signals available were a very few who had acquired ex-BBC or ITV converters. Alternatively you could point a 405 camera at a 625 monitor. EIther way, there was no convenient source of 405 signals for vintage sets. Hence the circulation of 405 line VHS tapes. With the availability of compact standards converters the need for recording 405 went away. I have written about all this in several artcicles which are on my website.

With the excellent Aurora and Hedghog converters readily available, providing 405 line signals for your vintage TVs is very easy.

[Richard_FM]

I thought so, thanks for filling me on Spot Wobble.

I believe some 405 line tuners were made for used with reel to reel video recorders, with I assume a line output.

[Mike Watterson]

There were EIAJ cartridges, N1700, N1500, Umatic and EIAJ reel to reel before Betamax and VHS. There was maybe seven to nine years of Betamax and VHS overlap of 405 TV (1976 or 1977 to 1985 in UK and Ireland).
The V2000 format hardly made it to the market as Philips had to keep putting off release due to manufacturing issues. It had piezo driven heads so could track at any speed or stationary.
I remember having the loan of both EIAJ open reel and N1500 or N1700 in 1979. I had a mono TV with the standard switch soldered in the 625 position, an added transformer and video in/out I added. So I never made 405 recordings.
The Betamax and VHS not only killed off EIAJ machines of all types, but the N1700. Umatics hence forth were only used in semi-professional applications were ther VHS was unsuitable.
It was obvious even before 1982 that V2000 and Betamax were doomed, even though Betamax may have still been produced till about 2001 or 2002.
I'd serviced or installed all sorts of video recorders in the late 1970s up to Umatics, but never even saw a V2000, ever. The craziest machine I saw and used was a portable Akai using 1/4" reel to reel tapes. It even did colour. Colour was rare on the EIAJ except the National version using a cartridge. It had to be completely rewound to eject and had a big stiff leader.
I had a company in the early 1980s buying black Thorn/Ferguson mono TVs without tube and adding amber or green CRTs from Fivre in Italy. It had only video and audio in. We removed the tuner and put our plate with logo there. I don't remember if the AV in was anything more than two sockets, one replacing the aerial. We sold hundreds to schools for Apple II and BBC machines. Nicer than the metal cube CCTV screens often sold with Apple computers then.

Back in the late 1970s the only multistandard customers were interested in was NTSC + PAL. The VHS and/or Betamax resulted in 4.43 NTSC due to VHS machines using the same colour under subcarrier for NTSC and PAL. Some of the VHS machines would play NTSC tapes at 30/60, but the subcarrier would be at the PAL frequency.
Thus AV monitor TVs that could do PAL, NTSC 4.43 and sometimes actual NTSC existed. Barco, being Belgian , were the king of Multi-standard AT TVs, but I never saw any doing 405 line. I don't even remember any monitoring of 405 in the BBC CTA in the mid 1970s. I think maybe 1972 was the last time I saw 405 lines.

[Spot Wobble]

Thanks for sharing the file of the manual for me Jeffrey: I did want everyone to be able to view it.

I did try attaching it to my GVR post but wasn't sure if it would work. (Not sure if attachments are restricted for new forum members.)

Best wishes,

Francis

[ppppenguin]

The only VTRs designed explicitly to do 405 were professional 2" Quadruplex and 0.5" Sony CV2000. Many helical scan VTRs could do 405 in the same way as VHS can but none were actively intended to record 405. I've recorded 405 with Umatic (old fashioned lo-band Sony 1800 series probably) as an experiment and it worked.

If you wer a broadcaster using Quadruplex then you'd have all the relevant kit. If you were a home/industrial/educational user with CV2000 you would typically use a 405 receiver/monitor with your recorder. The CVM90 is actually a bit later than the CV2000 but the Sony TV9-306UB I think could provide 405 video out from off-air reception and was the usual set to use with a CV2000.

The CV2000 begat the very similar looking CV2100ACE, 625 line, tape running at 11ips, which was widely used in schools.

[peter scott]

I inherited a V2000 that needed me to replace its head motor. It worked very well and I liked the auto-tracking piezo head mounting. I never tried recording 405 onto it. The 625 video quality was similar to/no better than VHS.

Peter

[ppppenguin]

405 on a 625 VTR can work very well indeed as it needs less bandwidth for top quality pictures.