THOMSON Proscan LaserDisc PSLD40 Installation guide

PRoScAN RCA
LASER si?
Technical Training
Manual
THOMSON CONSUMER ELECTRONICS INC. /TECHNICAL TRAINING
P.O. BOX 1976 INDIANAPOLIS IN 46206
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FOREWORD
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This technical training manual addresses the operation and troubleshooting of the
ProScan model PSLD40 and RCA model LDR300. The principles of operation and
troubleshooting techniques presented in this manual can be applied to all laser disc
players.
NOTE: This manual is intended to be used as a servicing aid and is not intended to
replace the service data. Servica data for these instruments contain specific informa-
tion on parts, safety, and alignment procedures. Service data should be consulted
before performing any service.
Safety Information Caution
Safety information is contained in the appropriate RCA or ProScan Service Data.
All product safety requirements and testing must be completed prior to returning the
instrument to the consumer. Servicers who defeat safety features or fail to perform
safety checks may be liable for any resulting damages, and may expose themselves
and others to possible injury.
CAUTION; The laser diode emits invisible infrared radiation, which is dangerous to
the eyes. When servicing the laser disc player do not look directly into the laser lens.
NOTE: All integrated circuits and many other semiconductors are electrostatically
sensitive and require special handling techniques.
Prepared by
Thomson Consumer Electronics, Inc.
Technical Training
600 N. Sherman Drive
Indianapolis. Indiana 46201
First Edition 9043 - First Printing
Copyright 1990 by Thomson Consumer Electronics, Inc.
Trademark(s) Registered Marca(s) Registrada(s)
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CONTENTS
Introduction 5
Features 5
Laser Disc Overview 6
Video Disc 7
Digital Audio 11
The Laser Disc Player 13
Overview LDR300 17
Mechanism 17
System Control 18
Servo 18
Signal Processing 21
Overview PSLD40 23
Mechanism 23
System Control 25
Servo 26
Signal circuits 27
Service Procedures 28
System Control 29
LDR300 29
PSLD40 30
Servo Section 34
Focus Servo 34
Height Servo 38
Tracking Servo 39
Slider Servo 41
Tilt Servo 43
Time Base Correction Servo 46
Signal Processing Section 50
Video Section 50
Digital Audio 52
Analog Audio 54
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Appendixes
Appendix A
Test Mode 56
Appendix B
Laser Power Confirmation 59
Appendix C
Laser Lens Cleaning 60
Appendix D
IC201 (Digital Audio Decoder) 61
Appendix E
ICI 1 (Mode Control Microprocessor) 63
Appendix F
IC801 (Mechanical Control Microprocessor) 64
Appendix G
IC601 (Servo Controller) 66
Appendix H
IC901 (Time Base Correction Servo) 67
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INTRODUCTION
The ProScan PSLD40 and the RCA LDR300 can be
grouped into a new category of laser disc player. This
category is called multi players, these players have the
ability of playing all available laser disc formats. The
advantage of a multi player is the elimination of separate
components to play video discs and compact audio
discs. This advantage alone saves space and greatly sim-
plifies connecting the laser disc player to the audio video
system.
Both the RCA and ProScan disc players implement new
features not previously found in laser disc players. One
of these features is a one bit digital to analog converter.
The new design generates less noise in the conversion
process when compared to multi-bit converters.
The PSLD40 has an additional feature of dual side play-
back. This enables the PLSD40 to play both sides of a
laser disc without having to remove the disc from the
player. This allows remote control selection of informa-
tion from either side of a laser disc.
Features
Some additional features of the PSLD40 and the
LDR300 are.
On-Screen Programming
Displays the operating status of the player on the televi-
sion screen, and on the front of the unit. Plus, video
prompts are used to assist the operator in programming
the players features.
Direct Access Play
Instantly accesses any point on a disc for playback. The
player searches for that point and resumes normal play-
back from that point forward.
Memory Repeat
On the operator's command, memorizes a location on a
disc. The player will then search for that point and
resume playback.
Still Frame
On CLV (Constant Linear Velocity) formatted discs the
laser disc player can still pause on one frame of video.
Because there is no physical contact between the pickup
of the player and the disc, this pause can be held
indefinitely.
Intro Scan
Plays the first 8 seconds of each chapter or track on a
disc. This gives a preview of all the material recorded on
the disc.
Random Playback
Plays chapters or tracks of a disc in a random order.
This allows familiar disc to be played back in a unfamil-
iar order.
Auto Program Editing
Automatically calculates the length of songs, or tracks
on a disc that will fit in order, on each side of a tape.
Stores the time into memory and uses this information
to place the laser disc player in pause mode, when one
side of the tape is full. This greatly simplifies dubbing
from laser disc to tape.
Compu Program Editing
Determines the length of the songs, or tracks on a disc.
Then resequences the songs or tracks to fit the maximum
amount of material on each side of a tape. The laser disc
player then plays them back in that order for recording
onto a tape. In this mode the laser disc player will auto-
matically go into pause mode when one side of the tape
is full.
Videoline"' Remote Compatibility
Permits RCA stereo monitor-receivers with Vid e olinkTM
remote control to command the laser disc player.
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LASER DISC OVERVIEW
In the reproduction of video and audio signals, the laser
disc format has definite advantages over the tape and LP
records. In video reproduction the laser disc can
reproduce up to 425 lines of horizontal resolution, out
performing broadcast, cable, and video tape formats.
Audio reproduction with the laser disc player provides
the clearest, and cleanest audio available for home use.
In the laser disc system a laser beam is focused on the
surface of a rotating disc. The disc has a series of bumps
(commonly called pits) etched spirally from the inside
edge to the outside edge of its surface. Information is
stored on the disc by varying the length of these pits. To
detect this information the laser disc player monitors the
level of light that is reflected from the discs surface back
into the optics of the laser disc player. For example, if
the laser beam strikes a flat surface on the disc, all of the
beam is reflected back into the optics of the player. In
comparison, if the beam strikes a bump (or pit) on the
disc surface some of the light is reflected away from the
optics reducing the amount of laser light entering the
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LASER
optics. The laser light that is not reflected away from the
optics is canceled by the laser light being transmitted by
the laser assembly. This cancellation is caused by the
height of the bump above the disc surface. This height is
1/4 wavelength, when the laser beam strikes the bump
it's phase is shifted by 180 degrees (See Fig 3). When the
phase shifted reflected signal strikes the transmitted
laser light the two signals cancel out, further reducing
the amount of laser light being reflected back into the
optics of the laser disc player.
The light that is reflected back into the optics of the
player varies in amplitude as the beam strikes the differ-
ent surfaces of the disc. This varying light is separated
from the transmitted light by the optics of the laser
assembly. Once separated the reflected light is applied to
a sensor that converts the varying levels into a electrical
signal. This electrical signal is called the RF signal. The
frequency of the RF signal is related to the length of the
pits (See Fig 4). The RF signal is then passed into the
signal processing stages where it is demodulated.
BEAM STRIKING PIT
Fig. 3 - Pit Detection
ttt
BEAM STRIKING
FLAT SURFACE
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Fig. 4 - RF Signal
The processing and demodulation of the RF signal
depends on the type of information recorded on the disc.
For example, to process an RF signal that carries video
information, the signal must be FM demodulated. A RF
signal that contains a digital audio signal must go
through processing to convert it back to a analog signal.
Video Disc
In the video disc format, the video information and the
analog audio information are independently FM modu-
lated and recorded on the disc. A digital audio signal
can also be added to some discs. This digital audio sig-
nal is optional, and is not included on all discs. When
included on a disc it is multiplexed with the FM modu-
lated signals for recording on the disc.
' quip ,
The frequency spectrum for the different signals rec-
orded on a video disc is shown in fig 5. The video infor-
mation is FM modulated with a center frequency of 8.5
MHz and a deviation of + /- 1.7 MHz. Unlike VCR for-
mat the video disc format does not separate the chroma
information from luminance information for recording.
This reduces the processing involved to play the signal
back and provides a clearer picture. The two analog
audio channels are FM modulated at 2.3 MHz for chan-
nel 1 and 2.8 MHz for channel 2. Both the analog audio
channels have a deviation of +/- 100 KHZ. The digital
audio information occupies the 0 to 2 MHz region of the
spectrum.
A block diagram of the laser disc record process is
shown in fig 6. The video and analog audio information
are independently FM modulated. Once modulated the
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DIGITAL
AUDIO
O
-10
-20
-30
2.3Mhz
CH1
ANALOG
AUDIO
2.8Mhz
CH2
ANALOG
AUDIO
8.1Mhz
9.3M 1 hz
7.6Mhz
FIJ
Ti I É
0 2 3 4 5 6 7 8 9 10 11 12 13 14
VIDEO
SIGNAL
VIDEO
MODULATOR
Fig. 5 - Frequency Spectrum of LD Player
L AUDIO J L CHANNEL I
MODULATOR
R AUDIO J R CHANNEL 1
MODULATOR
DIGITAL
RIGHT
CHANNEL
DIGITAL
LEFT
CHANNEL
DIGITAL
AUDIO
PROCESSING
MIXER 1
VIDEO
ANALOG AUDIO
MIXER 2
ANALOG
AUDIO. VIDEO)
DIGITAL
Fig. 6 - LD Record Process
UMITER
GLASS
DISC
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