CurtPalme.com Home Theater Forum

thelasernut · Joined: 10 Jan 2007 Posts: 24 Location: London UK

Does anyone with a collection of older CRT Projectors have a Rank-Cintel model 60230 Front Projection Monitor from the 1960's ???

These machines are closely related to the Rank-Cintel 35mm Tele-Cine flying spot scanners of the same period in so much as they use similar 4 inch CRT's except the face-plate of the scanner is FLAT while the projector's RGB CRT's have spherical Face-plates to match them to the 10.5 inch Mirrors used in each of the RGB Schmidt Optical System.

These D303 4 inch Rank Precision CRT's are run at 30kV and 1mA peak Cathode Current and are Air Cooled by blowing filterd air through a hole in the center of each mirror, each tube label says D303 but the labels are coloured to indicate the phosphor

Made in the 1960's to project a 6 foot wide colour picture, they were used in TV studios and Medical Schools as well as Flight Simulators, as there were no colour TV valves at that time they use small transmitting valves in some areas and the total valve count is around 100 devices. The whole projector uses around 1.3kW and has Scan Switches to select between 405 / 525 /625 Line operation. The projector weighs around 650 Lbs

Some machines were fitted with 3 x White CRT where a high brightness projector was needed and finally it was noted that the whole system is so stable that once converged - the picture would remain registered for several HOURS at a time

gjaky · Joined: 05 Jun 2010 Posts: 2790 Location: Budapest, Hungary

Do you have a picture of it? Sounds interesting!

thelasernut · Joined: 10 Jan 2007 Posts: 24 Location: London UK

I might be able to take a few pictures of bits when I can get to them but the original pictures and adverts were in copies of the SERTS magazine which i seem to recall was called TELEVISION

Some while ago I wrote to the society to ask if they had pictures - but SODS LAW was active and it seems they only have Bound Copies in their Archives - and in the process of Binding the loose copies they ditch ALL of the product Adverts.

Another large screen projector which seems to have disappeared completely from the internet is the PHILIPS MAMMOTH - this again used mirrors because they are so much faster than Lenses and give more light output. like most of the commercial PJ's of this time they used 5 inch CRT's with forced air cooling

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

Here's a PDF on the Mammoth:

http://www.extra.research.philips.com/hera/people/aarts/_Philips%20Bound%20Archive/PTechReview/PTechReview-15-1953_54-027.pdf

thelasernut · Joined: 10 Jan 2007 Posts: 24 Location: London UK

Many thanks for the information about the Mamoth Projector - Later versions were similar to the Rank Cintel Colour Projector in as much as they used 3 primary colour CRT's mounted horizontaly In-Line and used electronic correction to acommodate geometric distortion caused by the two outer Optical Systems being at an angle to the screen - unlike the Green unit which being square on to the screen did not require image correction.

The Philips technical paper you provided the link to reminded me of another which dealt with the problems of Converging the primary colour images on the screen to produce full colour pictures.

Philips designers had it in their heads that the obvious way to remove the need for any corrections would be to mount the 3 CRT's in a "T" shaped arrangement around crossed diachroic mirrors - in this way each CRT would appear to be square to the screen and a single lense could be used to throw the image on to the screen.

To prove or disprove the idea they built 2 colour projectors - one having the crossed mirror system they had proposed - and another using an in line arrangement of schmidt optics which then needed development of the elecrical correction system for the 2 outer optical systems - clearly these need two forms of image correction before the images will converge - firstly the images will have Keystone errors due to the increasing distance to the screen caused by the inward tilt of the outer optical units - secondly the same increasing light path effectively speeds up the trace forming the raster and so a compensating deflection field is needed to progresivley slow down the "spot" and restore a linear raster at the screen.

Having built these two machines and made comparisons between them - it became clear that in EVERY WAY the in line system was superior as it had less optical losses making for a brighter picture with better contrast and definition - hence all the later work was on in line optical systems and in developing the required elecronic correction methods.

The Rank Cintel 60230 has seperate deflection coils to provide corrections and these are mounted behind the scan coils of the 2 outer optical units.

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

As I recall there was an Electohome projector that also fired all three CRTs into an optical prism cube assembly and had only one lens. Kind of an odd beast, and they didn't continue the idea. Obviously this makes for a rather large projector since it has to be wide enough to fit three tube assemblies into it, left, right, and rear. This arrangement is standard, however, for all three chip LCD, DLP, and LCOS projectors, but of course those devices are enormously shorter than any CRT.

I enjoy seeing the various projection technologies. I really loved learning about the CRT driven light valves (LCOS) that AmPro
used in their 7000 series projectors. I greatly enjoyed playing with the ones I got at the AmPro bankruptcy auction.

thelasernut · Joined: 10 Jan 2007 Posts: 24 Location: London UK

I always wanted to see an Eidophor Projector such as made by Gretag - they seemed a most unlikely device but I guess it could really be the forerunner of the Micro Mirror devices used today.

I did manage to see a B/W unit that was buit into an Imhoff Cabinet at some sort of party but I was really dissapointed to find that the real job that was supposed to be running colour pictures at a presentation ( where Phiiips had a 3-D display using a couple of their Coffee Table projectors based on the K12 CTV Chassis - these displayed on the normal 5 foot diagonal Curved Silver Screen supplied with the projectors and the source was a pair of synchronised Laserdisc players ) but it turned out that the weather was TOO DAMP and the EHT kept failing when the Eidorphor was turned ON

For anyone who has not heard of an Eidorphor - its an electro-mechanical device illuminated by a powerfull lamp which could throw a 20 metre wide picture.

I consists of a sort of a CRT which has a replaceable Cathode and so has to be continuously pumped down with a Vacuum Pump, the "Face" end of the Tube contains a spherical Mirror which is mechanically rotated at slow speed and has an Oil Film on it which is smoothed by a fixed Wiper Blade

The Gun of the CRT fires at the Mirror Face and as it is Scanned and Modulated a "Picture" is built up in the form of "Stress" ripples in the Oil Film so when the Oil Film is lit up by the Light Source the image can be seen as areas of different brightness in proportion to the Stress.

To get a projected image Schlerian ( or whatever the correct spelling is ) Optics are used which is basically a Venetian Blind made with Mirror Slats - when the Light source is bounced off of the Mirror Slats so that it hits the Oil covered Mirror in the Tube - If there is NO stress in the oil film the light bounces back onto the Mirror Slats and so does not exit to light the screen - if however there is stress in the Oil - then light is reflected back at an angle which allows it to pass through the GAPS left between the individual Mirror Slats and when projected via a Lens system forms a picture on the screen.

As usual - 3 primary colour lit assemblies are used to form a colour picture - and as mentioned the Swiss Gretag Eidorphor could give a bright 20m Wide Image

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

GE made an Eidophor projector called the Talaria. Same basic technology. I worked for a man who had one, for a while.

Never saw it running, though, because it required 240 volt power and there wasn't 240 volt power in the building.

The first AmPro light valve projectors were called Eidophors, though they didn't use the Eidophor mechanism. They were LCOS light valves, CRT addressed via a fiber optic faceplate on the CRT. JVC was doing that before AmPro, and actually AmPro infringed on the JVC patent. But when AmPro bought out the light valve manufacturer, Greyhawk Systems, some people who worked for Greyhawk did not choose to stay with the company and with them went the knowledge (not written down, of course) of how to correctly seal the light valves.

So every light valve made for a couple of years would leak and break down and that cost AmPro so much money to fix it, using NEW bad light valves to replace bad one, which themselves would fail, that it killed the company. They DID find the problem and they did solve the problem, eventually, but too late. They went bankrupt and at their bankruptcy auction I ended up with six light valve chassis and got four working machines out of them.

garyfritz · Joined: 08 Apr 2006 Posts: 12025 Location: Fort Collins, CO

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

Hey, it worked! Rather well, actually.

Here, THIS simple little demonstration will cause you to visualize for yourself how an oil film Eidophor projector can create an image.

https://www.youtube.com/watch?v=UwVi-Lf1zBw

thelasernut · Joined: 10 Jan 2007 Posts: 24 Location: London UK

It's amazing how one thng leads to another - having read more about Eidophors from links in some of your postings I now find the TYPE NUMBERS for the Philips Mamoth projectors and these in turn lead to the relevant Data Sheets

MODEL EL5770 - MONOCHROME PROJECTOR - ( SINGLE TUBE )
MODEL EL5795 - COLOUR PROJECTOR - ( TRIPLE TUBE - RGB )

The EL5795 Colour Projector although a much bigger machine does seem to be comparable with the Rank Cintel Model 60230 in terms of power consumption -V- Picture Size - main differences being in Deflection and EHT power - the general electronics and cooling fan loads will be similar

EL5795 - PICTURE - 13 X 10 FEET MAX- 5 INCH CRT's on 80 kV into 13.5 INCH MIRRORS - MAINS POWER CONSUMPTION - 2.0 kW
60230 - PICTURE - 8 X 6 FEET MAX - 4 INCH CRT's on 30 kV into 10.5 INCH MIRRORS - MAINS POWER CONSUMPTION - 1,3 kW

https://www.google.co.uk/url?sa=t&source=web&rct=j&url=http://www.marcelstvmuseum.com/folders/Philips%2520EL%25205795%2520large%2520screen%2520colour%2520projector.pdf&ved=0ahUKEwi3-rv166LRAhXrI8AKHRuTDjgQFggdMAE&usg=AFQjCNFQgrFrlPlIY5rwmZfvv2ehY9yPcg&sig2=K20KXdwimksi0Tr89-h6Kw

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

80KV anodes, 5" tubes, 13x10 foot screen, I'll bet the tube life was a matter of hundreds of hours!

And talk about a technician killer!

Also, can you say X-RAYS? Yes, you can!

**Curt Palme** · Posted: Mon Jan 02, 2017 2:54 pm Post subject:

thelasernut · Joined: 10 Jan 2007 Posts: 24 Location: London UK

X RAYS - I got hooked on Projection TV in my early teen's when I saw 405 line UK TV projected using the Mullard / Philips folded Schmidt Optical box designed for use with the MW6-2 projection CRT which is a 2.5 inch B/W tube running on 25 kV with combined Blue and Yellow phosphors.

EHT came from a small sealed tin-can containing a Ringing Choke and 3 valve diode / capacitor tripler all submerged in Transformer Oil, the EHT came out via a cable terminated with the special connector designed to fit the funnel shaped glass tube around the Anode connection of these tiny CRT's

The Optical Box was designed to fit inside Table Top TV's and give 14 or 17 inch rear projected pictures using an internal plane cabinet mirror - this was compared with say a 9 inch direct view CRT of the day - but the same Optical Unit would also give a 60 inch diagonal front projected picture on a Silver Screen as in a Decca TV albeit with a different Corector Lens optimised for the longer throw required. Many manufacturers included projection TV's in their 1950's ranges but they were also taken up commercially by a couple of manufacturers such as White Ibbotson and Nera and were used to give additional displays - for example in the London Earls Court stadium during a Billy Graham UK tour.

The cast metal Mullard Optical Box was sealed to exclude dust but in some places this was only by thin paxolin (resin / paper) sections and I was always a little concerned by the possibility of X-Ray exposure - especially as I would be sitting near the Optical Box watching a picture projected onto the opposte wall. Around this time we were also reading about problems in the US where early CTV's had been mounted up high in some Dinners so people were being exposed to radiation coming from the un-shielded bottom of the TV - sadly the set designers had only taken X-Ray precautions with the top and sides of these TV's on the assumption no one would be underneath the set in any domestic situation.

I was starting to read about some experiments with Colour TV in some UK Universities by using Mullard Optical Boxes fitted with primary colour CRT's - I found there was no problem getting hold of Optical Boxes but RGB tubes simply did not exist - except for an Orange tube intended for some sort of radar display. Some months later I found an advert for the ex BBC Rank Cintel PJ and eventually went to view it - not realising I would see only a large pile of bits and pieces laying at the back of a lock-up garage - but I was hooked on CRT so i just had to have it.

After much cleaning / washing / drying / part assembly / watching for where the "smoke" was coming from / repairing - I had a working Projection Monitor needing RGB inputs - I did not have a TV Tuner with Video Output so I had to hack one out of an early philips TV chassis to get a Composite Video signal - then I was able to see a poor contrast B/W picture. Eventually I found a surplus shop selling panels from a commercial PAL decoder from the PYE company which gave me standard RGB video. Around this time the Chistmas Lectures from the London Royal Institution were being broadcast on TV and were about Colour Vision - so it was quite exciting to see the individual RGB optics on the 60230 light up WITHOUT the others, other things which sticks in my mind are watching the original Star Trek and seeing the Moon Landing live at 3 am in the morning.

With X-Rays always on my mind and the 60230 running on 30 kV I got hold of an old valve Rate Meter and spent some time pestering the Geiger Muller section at work for an X-Ray sensitive GM tube. The Rank Cintel projector is awash with Danger X-Ray labels on various pieces of metal protecting possible exit points from the Schmidt Optical Assemblies - so armed with my Mica Window GM Tube I proceeded to look for any signs of the dreaded X-Rays - but found nothing - however - what really suprised me was the response of the GM Tube to the BLUE projector.

When Light from the RED and GREEN fell on the Mica Window of the Geiger Muller Tube - there was no significant increase in Background Count - BUT- when Light from the BLUE projector fell on the GM tube - it went beserk. The "High Frequency" of the BLUE light seemed to have had enough energy to activate the GM tube on its own

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

Ever had day-glow materials in the same room with a CRT projector? The blue tube's output has enough near UV in it to make day-glo materials light right up.

I have a substantial sized roll of adhesive backed lead foil. It's about a 10" wide roll, and there's got to be 20 feet on the roll.

When I'm FINALLY done getting a tube and its magnetics right, I line the tube housing (Marquee type, of course) with lead foil inside it. I delete the outer shield flaps as there's no need to double shield the chassis.