Motorola/CBS EVR

[Dave A]

I went out today to look at some tv's and radios a friend was clearing out. A Pilot tv was ok. On the shelf below was a Motorola EVS player. Or recorder as CBS/Motorola called them but they do not record. It is a 1969-1971 effort by CBS to get a player in to the educational market and maybe home. It is a unique player that uses a pre-recorded film cartridge that self-threads and plays past a photomultiplier tube(s) to reproduce BW or color depending on what was recorded just like a B&K tv analyst. It has no grippers and just rolls past the tubes with a tiny sync pulse visible between frames on the film telling the circuits that a new frame is ready. Early Betamax killed the project $20 million dollars later. Both came home. It is the same as one gifted to the ETF in 2017.

A BW film is side-by-side on the 8.75mm film so there are two separate programs projecting through two lenses to two photomultipliers. You can switch electronically between them. The color version is luminance on one side of the film strip and chroma on the other. Early Y/C. I will leave it to others to explain. As such, a color film is half the length of the BW as both sides are used. Color uses both tubes together through separate chroma circuits. The CRT is ultraviolet as I have read. Audio is a magnetic stripe on both sides so it can be a two channel audio (English/French). The film can be spliced like 8mm with tape if needed if the film breaks. If the rather ridged leader breaks you can buy one from Motorola.

After finding the power cord and after 15 years on the shelf, we just lit it up. The capstan ran. Good so far. Inserting a BW film it choked and needed several tries to get it to thread. I had to try to figure out the proper bit of film to stick out to get it to grab. The manual shows about 3" outside the reel. No good. I tucked it fully in to the reel and that grabbed and it went fine to the internal takeup reel. But the problem. It has an internal vertical lock problem. It rolls but I have all the manuals to start but if anyone has hints, let me know. All the boards are edge connectors so I may start by pulling them and cleaning. Start small.

The paper that came with it shows hundreds of films available but not one entertainment show in the bunch. Let me know if you have any on the shelf. I would like to get it working and xfer them to digital for viewing. Especially the color versions.

I have to create a space to work on it and find a monitor to view. Video or RF is available. Pix when I can get it set up. Google it and you will find more than will fit here.

[old_tv_nut]

Lack of vertical sync could be several things, but first to check is the tiny fiber optic end in the middle of the film gate. If the fiber optic is clogged with dirt, there is no signal from the sync window track to sync the film speed. A much less likely failure would be the lamp that illuminates the fiber optic. Of course, it could also be an electronic failure, bad board connection, etc.

[Dave A]

Wayne's clue got it going. I cleaned the paths and still not working. In the dark I found the lamp was out. Then I found the lead that had popped off. Now synced but a BW pic is not good for posting with all of the sync bands.

I ran a BW cartridge over and over to loosen it up. Worst problem was the focus was drifting in and out. When I ran a color reel I got an image with color smears on the left side. Pic below. More running seemed to lessen the focus drifting.

Then I went to the mechanical focus just for fun and found it to help the color as the chroma channel stripes are now in better focus. The smears were residue of it not being in focus and not reading the information. Focusing by eyeball was not working. I found I could adjust to get rid of the smears. Switching between BW and color showed burst was kicking in. You have to work in the dark with the top off because room lights leak in to the photomultipliers.

The three films I got with it are all night-time dark and color is hard to see so on to adjustments. The important ones for video and chroma are hidden under a top plate that needs to have the side and bottom removed. 20+ screws or so. Another day and a bigger bench.

[Electronic M]

I wonder what light frequencies the photo multipliers are sensitive to? Perhaps if they are insensitive at the red or violet ends of the spectrum you could get a LED or similar source that doesn't produce light outside of the color you want and have something like a film dark room light to work on the machine by.

[dishdude]

Any chance you could share some pictures of this player? It sounds interesting.

[Dave A]

Tom, the CRT is only visible under darkness and it is a darkish blue scan with a bit of retrace going on. UV I suspect. It would have to be a big LED array to do the same. If the lid is open to light, you get white streaking across the frame from the room lights in to the PMT's. The PMT's have no markings on them and the manual only gives Moto part #'s and they are tight in the sockets so I will not force for now.. Unknown for now. Dude, photos below in two posts for all nine photos.

1 - Full unit cleaned up. Reel goes under black lid.
2 - Play, still and track select controls. There are different versions.
3 - Supply reel platter. Leader threads CCW in to a slot in the UR of the box.
4 - Take up reel with all optics visible. CRT is under shroud aimed at A/B
lenses. Lenses see both tracks at one time and divide them to PMT's
5 - Shroud off to show CRT and lenses. Triangular item covers light divider
guides to each PMT. One for A, one for B. Not sure if divider is glass
or acrylic. Magnetic audio head is out of sight.


More to come.

[dishdude]

Wow, that's really cool. Never knew these existed...thanks for sharing!

[old_tv_nut]

The photomultiplier tubes were the most common type; if I recall correctly, a RCA 931A or Hamamatsu equivalent:
https://www.nonstopsystems.com/radio...etfax-931A.pdf

The Hamamatsu's were less noisy out of the box if you did not expose them to office lighting (even without power). We never did experiments to determine if the performance degradation was due to gain reduction, and also did not experiment to see if the performance would be restored by letting the tubes rest in the dark.

[old_tv_nut]

As you can see, the peak sensitivity is in the blue violet, which handily matched the CRT phosphor. The particular phosphor was chosen because it had the shortest persistence of any known, producing minimum smear that had to be compensated in the video preamp.

[Dave A]

Not posted are the rear connectors, all BNC for video and 1/4" for audio. A one off power connector. Audio and video out. Ch 3 rf output. Audio and video loop through for narration during playback and a camera when the deck is stopped. As it was designed in Europe it was a PAL format to begin with which gave 30 minutes playback. Moving to NTSC and Moto, it dropped to 25 minutes. Not sure if all the units were made by Moto. That would have been two formats to support. The film was an Ilford stock that was used for microfiche in the day. Very fine resolution and non-silver. All the masters and film production went through the Ilford plant in England and made for a supply chain nightmare.

Guessing the history, it is a collaboration of European chemical companies and Illford to sell more film. Let's make a video film player. CBS and Goldmark jumped in for North America. The film platters are very 45rpm size. Goldmark strikes again.

6 - The film path and both PMT's. Very simple auto load path.
7 - The light shroud off showing the CRT and lenses.
8 - Both lenses for A and B with brass knurled focus knobs nearby.
9 - Color and BW reels. Ridged leader showing for auto thread grabber.

More as I figure it out. Enjoy.

[Dave A]

Wayne checks in with the spectrum answer. Thanks for the help here. And now can you help me understand scanning first and later chroma frames.

The film travels at 60fps, not 24fps like broadcast pull down film rate. The manual seems to show that two film frames are scanned as they pass. Would that make for two fields making a full 1/30th frame? Is it a field player or full frame player? Does the unit count two film frames before resetting for the next?

And the chroma info on the B channel for color is a mystery. It is a series of vertical stripes looking like some kind of modulation scheme in that they vary in modulation like a LP record or an AM radio signal. How does that side by side striping work? Does it read top to bottom or left to right or all of the above? The film is too small to capture a view of the stripes.

[old_tv_nut]

The September 1970 issue of IEEE Spectrum has a cover and 12-page article that explains a lot. Unfortunately, it is covered by IEEE copyright, so I cannot share a copy.

https://ieeexplore.ieee.org/document/5213552

I'll try to answer briefly:

1) The film runs at 60 frames per second, locked on average to the AC line frequency, but the scan is normal 60 field per second interlace (actual, "random interlace" - the vertical and horizontal are not locked, the same as in a simple closed-circuit TV camera of that era).

2)In order to not require the CRT scan lines to fall exactly on scan lines on the film, each film frame is a blend of two successive NTSC fields. Furthermore, the scan used in recording the film master is wobbled slightly up and down at four times the NTSC subcarrier rate to fill in the blank spaces between the lines. Therefore, ther is no chance of moire' patterns due to the flying spot raster not matching the film raster. The resolution of the film is actually so great that the 14.31818 MHz pattern can be resolved under a microscope. The flying spot diameter is too large to resolve that, but when the electrical and optical focus are perfect, video response goes to 4 MHz, the same as broadcast TV.

3) The blending of fields required a video field memory for the recording process, which was a very expensive thing in the late 60s. I believe CBS used mercury acoustic delays at one time, and eventually went to magnetic discs.

4) When the film is standing still, the raster is 3 units vertical height to 4 units width, the same as NTSC. During motion play, the film moves one film frame height (3 units) in 1/60 of a second, so the raster height is increase to 6 units to scan 3 units of picture frame while simultaneously chasing the film position by 3 units in a 60th of a second.

5) The chroma frame contains two stripe patterns added together. One pattern is a constant pilot sine wave for frequency and phase reference, at 1/4 NTSC chroma frequency, or about 900 kHz. The other stripe pattern is the chroma subcarrier signal translated from normal 3.58 MHz to half that, about 1.8 MHz. The chroma sidebands run from about 1.2 to 2.4 MHz. In the model you probably have, these frequencies are separated by using band reject filters. In a redesign I did at Motorola, the frequencies are separated by linear-phase band-pass filters. These are much less sensitive to hue changes due to horizontal scan width and non-linearity. I'm not sure if any of the modified players got into the market. So far, every one I've seen has a schematic packed with it that indicates the older arrangement.

6) A little bit more about the chroma frame: The pilot signal is in phase with the NTSC
"I" signal, not color burst. This is so that intermodulation between the two sine waves (due to tolerances in film contrast) will not cause skin hue to deviate. It also means that the peak values of the combined waveforms are plus during skin tone and negative during cyan. Some baseband I signal is subtracted from the two sine waves (stripes) to compensate these extreme peak values so the film can handle them better.

7) The pilot waveform is doubled in frequency to be a frequency and phase reference to recover the chroma. They both vary together due to horizontal scan rate (width or linearity variation). By a sequence of frequency mixing steps, one of which involves a local 3.58 Mhz crystal oscilator, the variation in the chroma signal phase and frequency variation is cancelled out and is restored to a standard stable NTSC chroma signal. My later redesign used a first demodulation step using the doubled pilot, followed by remodulation on the crystal frequency. Either way works, but their are details about sensitivity to multiplier chip imbalances and so on.

8) You will see a "gamma" adjustment in each video channel. This is not the usual gamma correction in a video camera, but correction for deliberate stretching of the highlights in the recording. The idea is that compressing those highlights after scanning reduces the amplitude of CRT phosphor grain noise. Caution: it also affects the pilot/chroma intermodulation in a chroma frame, changing the hue of green and magenta colors.

[Electronic M]

Originally Posted by Dave A

Not posted are the rear connectors, all BNC for video and 1/4" for audio. A one off power connector. Audio and video out. Ch 3 rf output. Audio and video loop through for narration during playback and a camera when the deck is stopped. As it was designed in Europe it was a PAL format to begin with which gave 30 minutes playback. Moving to NTSC and Moto, it dropped to 25 minutes. Not sure if all the units were made by Moto. That would have been two formats to support. The film was an Ilford stock that was used for microfiche in the day. Very fine resolution and non-silver. All the masters and film production went through the Ilford plant in England and made for a supply chain nightmare.

Guessing the history, it is a collaboration of European chemical companies and Illford to sell more film. Let's make a video film player. CBS and Goldmark jumped in for North America. The film platters are very 45rpm size. Goldmark strikes again.

6 - The film path and both PMT's. Very simple auto load path.
7 - The light shroud off showing the CRT and lenses.
8 - Both lenses for A and B with brass knurled focus knobs nearby.
9 - Color and BW reels. Ridged leader showing for auto thread grabber.

More as I figure it out. Enjoy.

Goldmark was involved with the LP introduced in 1948 by Columbia...the 45 was introduced in 1949 by RCA and Goldmark was not on the team....The 2 formats were briefly in a rivalry till the makers realized the singles and album markets were different and they were better served coexisting.

[old_tv_nut]

No, not a European development, but Ilford was lured into the project, as were the player makers as well as Motorola. There were a series of agrements on intent to participate with various companies that dropped out and were replaced as CBS dawdled over just how the system would be marketed (entertainment or institutional). The system could have been on the market five years earlier if Paley had not repeatedly changed course due to worries about devaluing CBS's entertainment properties (unlike Disney, who was the first to realize that TV and movies and theme parks could reinforce each other).

The color format was designed to work for both PAL and NTSC from the beginning (though the film would need to be remastered for the different frame rate). The lack of resolvable scanning lines meant that it could be scanned in 525-line or 625-line format equally well. The PAL color format was produced by using the same color coding on the film as for NTSC, but heterodying up on one scan line, and down on the next, thus producing alternating R-Y phase. If you think about it, line-alternating the phase on the film itself would have re-introduced the problem of making the flying spot scanner line-by-line accurate.

There was a project at CBS for a fully broadcast-compliant version (Broadcast EVR, or BEVR) that could be used by the networks to syndicate their programs.

Goldmark was much in the mold of Edison, in that there was the appearance, at least, that all the system innovations came from him, and the CBS labs staff only contributed to implementation.

[Hawkwind]

https://archive.org/details/evr_demonstration_on_film

Blurb plus reviews.

Demonstration of the EVR video/film player.
To license this film and get a higher quality version for broadcast/film purposes, contact A/V Geeks LLC.

Addeddate 2011-06-22 17:15:40
Color b&w
Identifier evr_demonstration_on_film
Sound sound

Reviews
Reviewer: Lurking-Grue - September 13, 2015
Subject: Wonderful and weird.

Just a note to people that are confused by the name. This is a player only and the format required an expensive process to make the reels and it more resembled film.

Here is more information on the format:

http://www.cedmagic.com/history/cbs-evr.html

Reviewer: Spuzz - April 1, 2015
Subject: Limitless!
Awkwardedly hosted demo for EVR, which was a reel to reel film based player, at least. The more I think about it, the more suspicious I become. Anyways, this was a very interesting precursor to the home VCR, albeit with totally different technology. It's demonstrated ok here. The cartridge could hold 2 30 minute recordings on either side, The film fails to show how recordings are done though, or whether it was possible at home. I mean, if people wanted a reel with Mission Impossible and a rambling Robert Frost speech on it, theyre in luck. The host was curious, seemed to get more disttracted and taking these weird little pauses, which became longer as the film went on. Great little curiousity.

Reviewer: torgman - September 23, 2012
Subject: Maybe it would've sold better...
..if they didn't get a guy with a South Boston accent to sell it. "E-V-Ahhhh!"