CED Videodisc Workshop

June 28^th 2025

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Introduction

• Hello from CEDatum.
• What we will cover in this workshop.
• Special Guests.
• Group Picture.
• Hands on.

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What is the RCA Videodisc System?

• The RCA Corporation began development of a picture disc system back in the early 1960’s.
• They found that through capacitance a signal could be transformed from a grooved disc into a picture. (What is capacitance?)
• Well CED, or the Capacitance Electronic Disc, used an electronic signal that would pass through the disc to collect information off the surface.
• This was achieved by using a PVC (Polyvinylchloride) disc that had been laced with carbon to make the disc itself conductive to an electronic signal.
• By creating a series of pits and valleys on the disc the electronic signal passing through the disc can detect how high or low the stylus moves and translate that information into data. Kind of like Morse Code, or the 1’s and 0’s of computer code.
• The data is then compiled into a picture just like the data on your computer. It can then be displayed on your screen.

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What is a CED?

• A CED is made up of PVC or Polyvinylchloride mixed with 15% Ketjen EC Carbon Black manufactured by Akzochemie.

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About the Disc

The disc is 12 inches in diameter utilizing a spiral groove of V-shaped cross sections with a width of 2.66um(microns) or appx 9,541 grooves per inch.

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How does it compare to a vinyl record?

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• The spiral groove is 13 miles long and holds 1 hour of data per side, which is 175x more data than it’s audio disc counterpart.
• A normal audio disc is read at 33 1/3 RPM and holds about 22 minutes of audio per side.
• While the CED Videodisc is read at a speed of 450RPM and contains about 1 hour of audio and video per side.
• There are appx. 40 CED grooves per 1 audio groove.

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How is the disc read?

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• The information is detected by a stylus that rides in the groove, it detects the relief pattern by sensing the changes in capacitance from the tip of the electrode stylus and the surface of the conductive vinyl.
• The diamond tracks the groove while the titanium electrode conducts the signal.

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How does Capacitance Work?

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• The disc is composed of conductive carbon, and is etched with a groove that contains a series of pits and valleys. The disc is spun at 450RPM’s and a stylus consisting of a diamond with a titanium electrode trails in the groove. A 915MHz signal is sent through the disc, through the electrode, up the stylus and into an oscillator. The frequency it received will vary depending on the pits and valleys on the disc. The frequency is then adjusted by a frequency control and compared to the starting 915MHz frequency, the difference is then sent to a preamplifier and processed by the onboard circuit chips into the picture that appears on your screen…

915MHz signal sent…pits and valleys alter signal…820MHz signal received…

difference is 95MHz…computer processes 95MHz into data that can be displayed on screen.

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How was a disc made?

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• According to Timothy Bereman, one of the Mastering System Operators at Rockville Road.
• The studio would send over a 1” C Format “Broadcast Grade” videotape.
• The tape would be loaded into an Ampex VPR-2B machine.
• The video, chroma, and audio signals are transferred to the cutting head of the electro mechanical recorder. (Designed by Gunter John)
• The diamond cutting stylus then cuts the v-shaped groove, about 2.5 microns (.0001 inch) wide, into a heavy aluminum disc, 14 inches in diameter and coated thinly with copper.
• The newly cut disc created is called a “Copper Substrate”.
• The recording was done at half speed, taking about 2 hours per side.

In most cases these tapes were sent from the RCA Videodisc office in Hollywood CA. RCA and the Movie companies/studios used Post Production houses to do the film to tape transfers and tape prep work. The mastering tapes were made from the best archive film stock. The mastering tapes were sent to Rockville Road under high security. – John Stevens

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Tape Equipment

The mastering systems were very reliable. The only problems we seem to have were broken cutter heads and phase flips. That's when the video output would basically turn blue for one frame then flip back. Sometimes the output from the frame storer would invert the phase and video signal would have inverse phase momentarily. When that occurred, the recording attempt was aborted.

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- Timothy Bereman

All recordings were done at half speed. The cutter head was not capable of mastering at real time because of the high frequencies involved. The tape was ran at half speed which would double the frame rate. The video signal was read into a frame storer and output at half rate.

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The Cutting Lathe

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Then what happens?

• After the copper substrate was cut on a recording lathe, it went to laser viewing to ensure there were no abnormalities.
• Then it went to Matrix in which the copper substrate was plated to make the master, the mother and the stampers.
• Think of the master as a negative, the mother as the positive, and the stampers as a negative.
• The stampers were mounted on the press plates on the pressing machines.

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Final Pressing Procedures

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The copper master is then given a thin metal (nickel) coating which is built up by electroplating. Once removed this forms a negative replica called a “Metal Master”.

The process is then repeated to form a number of positive copies called molds or “mothers”, each mold can then be replicated to produce a number of negative replicas called “stampers” that are used to press the discs.

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Once stampers for both halves of the disc are made they are centered in a compression molding press. A “puck” of carbon loaded PVC is placed between the stampers and they are heated to 385 degrees and pressed together for 30 to 36 seconds. The excess is trimmed away and the disc is placed on a spindle to move on to the next process.

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Some other notes from Timothy.

• Not all recording attempts were successful. Sometimes the cutter head would break, sometimes a phase flip would occur, etc. I remember sometimes it would take up to four attempts before we cut a good substrate. And all we needed was one good substrate. The goal was to have all discs pressed from one substrate. On some titles we had multiple masters, mothers and stampers. But they all came from the same substrate.
• There were three NTSC systems and one PAL system. There were two mastering system operators and three recording lathe operators on first shift. First shift would complete 7 to 8 attempts per shift. I was the only mastering operator on second shift, with one recording lathe operator. I would typically make 5 to 6 recording attempts per shift. Attempts where labeled on the substrate with a -1, -2, -3, etc.

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After they are Pressed

• Once the discs are pressed, they go on to a special surface treatment.
• This treatment consists of a dilute amine solution followed by a warm distilled water rinse and a final drying step before moving on to lubrication.

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The Final Steps

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• Once the discs are pressed they move on to be lubricated.
• A normal audio disc stylus uses about 1 gram of tracking force while a CED stylus uses only about 65 milligrams. It was found that a lubricant was necessary to prevent intimate contact between the stylus and the disc surface by providing a nondestructive mechanism for dissipating the high sheers involved as the stylus slides in the groove.
• A product found to provide excellent results was a compound from General Electric’s Silicone Division called SF-1147 bearing a normal decyl group of [R=n-C10H21]
• SF-1147 has a freeze point of -65 degrees Fahrenheit to a flash point of 480 degrees Fahrenheit.
• (It is currently manufactured by Chemtrec and sold by Momentive Performance Materials.)

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Applying the Silicone

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• The SF-1147 was applied by diluting it in a mixture of isopropanol or heptane and coating to a thickness of 200-250 Angstroms or .1 nanometer.
• (Basically SF-1147 was a waxy compound that was mixed with alcohol and sprayed on the disc. The alcohol would then evaporate leaving the SF-1147 silicone bonded to the disc.

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How do I clean a CED?

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• The outer layer of skin contains microscopic pores that secrete sweat and oils. Sweat is mostly water, but it contains a very small fraction (1.5%) of salt, amino acids, and proteins. These chemicals remain on the surface after the water evaporates. The skin also contains sebaceous glands, which produce oils. These sweat and oils are what causes our fingers to leave fingerprints. When you touch the surface of the disc these chemicals interact with the SF-1147 on the disc and changes it's chemical makeup, making it

unable to protect the disc from the sheer of the stylus tip thus causing the disc and stylus to wear more quickly. That is why you must never touch the surface of a CED, or use any type of chemical to "clean" it.

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If you must "wash" a disc, rinse only with distilled water as it will evaporate leaving the SF-1147 silicone in tact, as it was. Do not use anything to rub, or dry the disc.

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All About the Stylus.

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• The first stylus RCA created was made from sapphire. In 1976 they were able to decrease the groove with from 4.6 microns to 2.7 microns creating a playing time of 1 hour per side. But in doing so they discovered they needed a finer stylus and found diamond to be the perfect replacement.
• The stylus is a titanium electrode affixed to the trailing edge of a diamond tip. It follows in the V-shaped groove of the disc spinning at 450RPMs, which means the stylus is covering about 500cm/sec. If the stylus looses contact for even .3 mm an entire line of video information is lost. If the stylus is kicked over by 2.6 microns or one groove then 133 msec of audio and video information are lost or repeated. (We call this a skip)

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Stylus Diagram

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Exploded Stylus Diagram

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Different Types of Styli

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154216

Real

Diamond

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154216

Artificial

Diamond

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160211

Bally NFL

Stylus

SJT400X

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J/K Stylus 149000/154100 F/G Stylus Hitachi

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Stylus Wear

• The titanium electrode of the stylus is approximately 2500 angstroms (.25 microns) thick. A human hair is approximately 1 million angstroms thick, meaning you could fit about 400 titanium electrodes in the width of a human hair.
• With a new stylus the titanium electrode will last 30-70 hours before it begins to form up. There is a small decrease in signal output at that time. The titanium electrode then only wears as fast as the diamond tip.
• At about 65 to 70 milligrams of tracking force the stylus will last about 200 hours with no loss of signal, or at least 50 plays.

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• Note: Mono F/G Players use 149000, Stereo uses 154100, in production 154100 was used in some mono players (SGT100 & SGT075 coded 2155 or later), to use 154100 in a mono player you must make sure it uses stylus arm 154036 with wide stylus sensors.

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Clean vs. Dirty Stylus

Dirty F/G

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Clean F/G

Dirty J/K

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Clean J/K

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History of the CED Player

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• Many players and discs were made in the development process, the largest quantity of players manufactured for R&D was the SDT200W Player. It represents approximately the 6th player design. In total over 430 complete players were manufactured of this model.

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The SDT200W

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• As you can see it is similar in design to our beloved SFT100W with the exception that the circuit boards were designed vertical and removeable and the arm sweeps right to left instead of back to front. It also utilized push buttons instead of our familiar light switch.

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The SFT100W

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The SFT100W Page 2

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The SFT100W Page 3

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The SFT100W Page 4

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The SFT100W Page 5

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The F Line Flow Chart

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The J/K Players

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The J/K Players Page 2

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The J/K Players Page 2

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The J/K Line Flow Chart 200/300

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The J/K Line Flow Chart 400

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CED Player Brands and Models

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CED Player Brand and Models Page 2

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CED Player and Brands Page 3

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CED Player and Brands Page 4

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Tool Kit

- Phillips # 1 screwdriver with a high quality tip

- Phillips # 2 screwdriver

- 1/4" Hex Head screwdriver

- 1/2" Hex Nut driver. 1/4" with narrow head

- 1/2" Hex socket with driver

- Electric drill with removable tips

- Allen or Hex key. 1/16"

- Allen or Hex Key. 1/8" with long reach

- Needle nose pliers

- Soft paint brushes for cleaning. 3/4" and other sizes

- Stiff bristle brushes for cleaning.

- Digital multimeter with DC and AC and Resistance Ranges

- Silicone grease for plastic and metal (white lithium grease)

- Light synthetic machine oil (3 in 1 oil, or super lube)

- Syringe for use with machine oil

- Omni-Lube 350 oil

- J/K belt remover solvent (glass cleaner with ammonia or household ammonia or 90% alcohol)

- Chemical resistant gloves

- Lint free wipes (handiwipes)

- Small flashlight

- Container for holding screws, etc.

- Spray contact cleaner

- Pocket ruler for 15/16 or 30/32 measurement on J/K players

• Dentist pick and flat probe

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• Sync Plate Gauge
• Stylus Height Gauge

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Technical Assistance

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• John Stevens has made a wonderful Mechanical Service guide for both the F/G model players and J/K model players. I won’t go over them in detail since we will be doing a hands on portion today that will cover most of this material but they are available for your viewing/printing pleasure here.
• RCA F/G Basic Mechanical Service Guide
• https://drive.google.com/open?id=1yA126Q5Thhw5bONS16rv-L2JlSoZGh3C
• RCA J/K Basic Mechanical Service Guide Page 1
• https://drive.google.com/open?id=1NU2b3ietNlRWFH3zeFJZ4kpNjpaloLam
• RCA J/K Basic Mechanical Service Guide Page 2
• https://drive.google.com/open?id=1PmtQHcOrtSYHY5gS1-BzvK_stVHWx5mA
• Useful Servicing Tips and Time Savers
• https://drive.google.com/open?id=1H1dVRiIP9nQmToT9VqmVMyjjZBIHe3iy
• Thank you!

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Links

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• CEDatum Parts and Services
• http://cedatum.com
• Tom Howe’s CED Magic Page
• http://cedmagic.com
• CED Magic Forum
• https://cedmagic.classicconnect.net/?fbclid=IwY2xjawI0h6VleHRuA2FlbQIxMQABHdc4RtH2ikGAoFvyMRx6tvNGKH-mFeA_CxVy_gDgewrM4_jncFFZRTtJ8w_aem_StFX7_Onhz0vzicFEB32jA
• CED Player Manuals from LDDB
• http://manuals.lddb.com/CED_Players/
• Some neat information on the Bally NFL game, also a J400 service manual and Addendum under the Tech Center link.
• http://www.dragons-lair-project.com/games/pages/nfl.asp
• Every Issue of RCA Review
• https://www.worldradiohistory.com/ARCHIVE-RCA/RCA_Review_Issue_Key.htm

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Common Q & A

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• I just picked up this player at a thrift store, how do I make it work and what’s it worth?
• How do I open a disc to clean it?
• I have some discs I inherited, what are they worth and what’s the best way to sell them?
• I just got a player and some discs but it keeps skipping, what do I do?
• I just got into the format, where’s the best place to buy discs?
• I can’t hook this up to my modern TV, what do I do?
• Where can I order new belts and a stylus?
• Why can’t I stack the discs?
• Any more questions?

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RCA Videodisc Clock

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• 1. You will need to measure 17 Centimeters from the top of the disc and 16.3 Centimeters from the side of the disc.
• 2. Place a piece of masking tape over it and re-mark it.
• 3. Remove the spine and disc and reinsert the spine only.
• 4. Drill your hole with a 5/16th inch drill bit.
• 5. Remove the tape and clean the hole, then remove the spine to pull any excess shavings out of the caddy.
• 6. Reinsert the disc and spine.
• 7. Insert the clock movement through the back of the disc, don’t forget to put the metal hanger on over the front of the clock movement.
• 8. Put the washer and nut on and hand tighten down.
• 9. Select your hands and attach.
• 10. Add battery and hang it.

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Thank You!

• I would like to thank everyone for coming to, and supporting the CED Videodisc workshop.
• I hope that we can continue to offer this workshop for many years to come and future generations can experience the joy of RCA Videodiscs.
• The workshop is a free event to keep the magic of CED alive, any donations are appreciated.
• I hope that everyone had a great time and I would like to present our special guests.
• Thank you.

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Please Welcome Our Special Guests

Robert Huck was the Manager of the VideoDisc Product Assurance and Test Organization. Prior to March 1981, he was manager of the VideoDisc Engineering Test Group and had been involved with VideoDisc development at Indianapolis since 1972. He had previously managed engineering teams in the development of videotape, computer tape, and magnetic disk packs. 

Byron Taylor was a member of the Engineering Staff, at VideoDisc Operations, Indianapolis, where he was responsible for the stylus cartridge design dynamics within the Stylus Cartridge Design group. He joined RCA's New Products Engineering area in Indianapolis in 1969. After first aiding design on the RCA holotape laser player and the Indianapolis recording facility, he has been continuously involved with player design of the VideoDisc system.

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