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Featured CED VideoDisc No. 43 - Winter 2007


RCA Service Alignment Discs (NTSC and PAL)

RCA SelectaVision VideoDisc Stereo/Mono Service Alignment DiscCED VideoDisc Service Alignment Disc For 625 Line / 50 Field PAL or SECAM Players

The featured CED's for this season are the Service Alignment Discs, which are used to have CED players generate consistent, predictable video signals when the units are undergoing electronic servicing while in the AC-powered service position. The NTSC disc is used to service players sold in North America, while the PAL disc is for players sold in Great Britain (and to a limited degree in Australia). I picked these for this feature, as I only recently acquired the PAL/UK format disc after years of looking for a copy. This has definitely been my most difficult CED title to find, with an effort that involved contacting practically every Hitachi dealer and service location in the United Kingdom. All the PAL-format players were manufactured by Hitachi and sold primarily at dealerships in the UK, so those were the places to look for this title.

Besides the stereo/mono Service Alignment Discs, there was also a mono-only Service Test Disc (in a white caddy) that was only available in North America during the first year of CED player production. When the stereo players were introduced in 1982, RCA replaced the Service Test Disc with the NTSC Stereo/Mono Service Alignment Disc and recommended no longer using the Service Test Disc, as it hangs up the newer players. This wasn't much of a problem with the "G" line players, as the disc could still be removed, but with the J/K players, the disc hangs the player to the extent that even the eject button doesn't work, making it difficult to get the Service Test Disc out of a J/K machine. It appears that many of the Service Test Discs were simply thrown away or damaged during the removal process, making this an Extremely Rare title today.

The pictures further down this page show all the signals present on the NTSC and PAL/SECAM Service Alignment Discs as printed on the back of each caddy. SECAM is a 625 line/50 field video format somewhat similar to the PAL format, and is used in France and some other countries, although CED players were never marketed in those countries. It's interesting to note that the PAL disc has a UPC bar code, while the NTSC disc is one of the few fully-labeled CED titles that lacks one. The PAL disc also has the diameter of the first modulated groove written on the disc caddy, while this information is almost always missing from NTSC Service Alignment Discs. The first modulated groove is simply the first groove on the disc containing a video signal and can vary slightly from disc to disc. The value was supposed to be measured and hand-written on each caddy at the time of packaging, but RCA apparently abandoned the procedure when the J/K line entered production. This value is used to determine the Stylus Set Down Position, but lacking this value, a trial-and error procedure can be used to determine the proper stylus set down adjustment.

Comparing the signals stored on the service discs, the NTSC and PAL versions often, but not always, have the same Segment letter for each signal on the disc. For example, Segment K is a Demonstration video on both discs and consists of a short movie titled Icarus about hang gliding. This segment is not actually that useful for servicing, as the video signal is continuously variable, but it is useful for general picture and sound check on an attached video monitor. Both discs also have a number of independent audio segments, where the A audio channel or the B audio channel can be accessed with the Audio A/B button or switch. In the case of the PAL system, this is the only title that makes use of independent audio, with the A/B channels being labeled Main/Sub on the remote control. In the NTSC format there were a few titles released in bilingual format, that made use of English and Spanish on the independent channels.

These discs also have the longest sides you'll find on CED VideoDiscs. The final V segment on the NTSC Service Alignment Disc starts at 63 minutes and is used to check the limits of arm travel, i.e. sometime shortly after 63 minutes the pickup arm should encounter a mechanical impediment and be able to travel no further. On F/G players this limit may actually be encountered around 61 minutes as the early players were designed with 60-minute-maximum discs in mind. The PAL disc has more segments than the NTSC disc owing to the slower rotation speed and consequent longer play time of the PAL system. So the final segment Z on the PAL service discs begins way out at 77 minutes. Note that these discs are also banded, allowing direct jumping to particular segments on band-enabled players. This banding is useless on the PAL disc, as there were never any PAL players sold that can seek to specific band numbers. But this banding is useful on the NTSC disc in conjunction with servicing the interactive SJT400 and SKT400 players.

RCA SelectaVision VideoDisc NTSC Service Alignment Disc Contents RCA SelectaVision VideoDisc Stereo/Mono Service Alignment Disc Contents


CED VideoDisc PAL/SECAM Service Alignment Disc Contents RCA SelectaVision VideoDisc Stereo/Mono Service Alignment Disc Contents

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