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CED Digest Vol. 3 No. 20  •  5/16/1998


Date: Sun, 10 May 1998 08:51:46 -0700
From: Tom Howe
Subject: RE: SJT-100 Question

On Sun Apr 26 "Frank Gregory" wrote:

>	I started patching one together from two non-working ones.  Got it to
>load/unload fine.  the player starts spinning the disk, and the stylus
>moves into postition, then it just sits there with the - - signal on the


This is one of the common modes of player failure where the player appears
mechanically functional, but displays the double dash forever after the
turntable spins up. A fully operational player would only display the "--" for
about six seconds, as the system control microcomputer waits for the stylus to
read the signal from the disc and the DAXI (Digital AuXiliary Information) to be
recovered. As soon as the DAXI stream is decoded, the time counter starts. The
failure of the signal to be read could have many causes ranging from a dead
stylus to the failure of any capacitor, diode, transistor, resistor, inductor,
IC, signal trace, or solder joint between the stylus tip, DAXI decoder, and
system control microcomputer. The best way to diagnose such a problem is to
progressively observe the signal with an oscilloscope starting at the stylus
cartridge. When a problem node is found, the individual components attached to
that node can be tested.  A less systematic way to accomplish this is to use a
multimeter in conjunction with the voltage charts printed in many CED player
service manuals to determine if the voltage is correct at each node in the


From: "Roagie" 
To: <>
Subject: Cleaning Discs
Date: Sun, 10 May 1998 11:03:42 -0700

Hello all-

I recently aquired a nice setup of 51 discs and a Sears player. I like it a
lot, it's very bazarre! Anyway, I have this Planet of the Apes disc that
refused to play... I tried to let the stylus clean it as recommended in the
FAQ but was only greeted with lackluster results. The machine would kep
returning to 00. Anyway, figuring this disc was a loss I opened it up and
removed the media. In a last ditch effort, I took a kleenex and went around
and around removing some whitish reside and dust. I then tried it again and
it worked good... played all the way through! Is there some reason kleenex
is not recommened? The disc woulda been a waste had I not done that...
Opinions and other cleaning stories appreciated! Thanks :)

From: Proton958 
Date: Tue, 12 May 1998 15:55:52 EDT
Subject: Re: For the CED Digest

Just found a old brochure from Sharp from 1981.  Its "Preliminary Information"
on the Sharp VHD Video Disc Player and Random Access Unit.  The Player looks
similar to a CED player and the R/A Unit is the same size and was designed to
sit on top of the VHD player.  VHD was very similar to CED but the disc size
was 10.2."  The disc was inside a caddy just like CED.  The player used a flat
diamond stylus guided by a tracking signal encoded on the grooveless disc.
Contact without grooves.  This eliminated many of the problems CED had by
using a groove system.  When hooked up to the Random Access Unit it was
possible to have special effects like still frame, slow and fast motion in
either direction and random access.  Sharp talks about plans for Audio High
Density (AHD) discs.  By connecting  an optional AHD PCM demodulator between
the VHD player and a stereo system, "you can enjoy the full benefit of the new
digital sound from AHD disc."  There were two sides to the discs just like
CED.  Playing time 1 hour per side.  Motor rpm was 900.  The VHD player  was
about the same size as a CED machine.  Weight 26.5 lbs.  The R/A Unit weight
was 99.2 lbs!!  I remember VHD was sold for a short time in Japan, but never
lasted very long and was not introduced to the U.S.  This is an impressive
4-color brochure and it looks like at one time VHD had much to offer.  Of
course optical became the system of choice just a short time later. 


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