RCA SelectaVision VideoDisc SFT 100 Service Data page 14

СЕО-1
ELECTRONIC/MECHANICAL SYSTEMS DESCRIPTION
16 MAGNETIC POLES
AROUND CIRCUMFERENCE
DRIVE POLES ARE OF TURNTABLE PULLEY
REVERSED AT A.C. LINE
ВАТЕ (60 HERTZ) ТО
MAINTAIN SYNC. ү
Fig. 1-8. — Turntable Drive Operation
The power line frequency is typically 60 Hz +.1%. The VideoDisc
player, however, is capable of correct operation even if the power
line frequency varies by as much as 1% of nominal. This is possi-
ble due to the action of the armstretcher and time base correction
circuits in the video converter stages.
The FUNCTION lever also closes DC Play switch S3 when placed
in the PLAY position. This connects the microcomputer Play Ena-
ble line to DC Spine Sense switch S6, previously activated by in-
sertion of the disc and spine in the player. This action grounds the
Play Enable input to the microprocessor through S3 and S6, plac-
ing a logic "Lo" at the microcomputer input. Logic "Lo" at this
point instructs the microcomputer that all critería for starting the
player have been met and the PLAY operation can now begin.
After a delay of approximately seven seconds, to allow the turnta-
ble to reach 450 rpm, the microcomputer instructs the stylus to be
lowered onto the disc.
In the Play mode, the reduction gear assembly clutch is engaged
allowing the servo motor to have total contro! over movement of
the pickup arm assembly.
End-ol-Play
After one side of the VideoDisc has been played, the time indica-
tor will flash an "E", indicating the pick-up arm is at the end of the
VideoDisc program. The function lever may then be placed in the
"Load" position (to remove the VideoDisc just played).
Unload Sequence
To remove the VideoDisc and spine from the player:
Place Function Switch in "Load" position. Insert empty caddy
through the caddy entry port door in the same manner used when
player was loaded. The same series of events will occur as occur-
red during the "Load" sequence with the following exceptions.
When the VideoDisc reaches "Еп of Play" the pickup arm as-
sembly will be at its innermost position (center of disc). The
empty caddy contacts the pickup arm pushback assembly allow-
ing the caddy to push the pickup arm back to its outermost posi-
tion. When the pickup arm reaches its outermost position, а tand-
ing adjust set screw, in the base assembly, contacts a pushrod
releasing the pickup arm pushback assembly tab allowing the tab
to swing free as the empty caddy continues to be inserted.
The empty caddy then contacts the caddy lock defeat tabs (these
are the tabls utilized to release the spine from the caddy during
the "Load" operation and dropped down as the caddy was
removed), pushing the tabs down onto the spine latch assembly
(Fig. 1-9). This forces the spine latch assembly to release the
Spine as the empty caddy is inserted. Push back springs force the
spine and disc back into the empty caddy locking it securely. The
caddy, with the spine and disc locked securely inside. can now be
removed.
SPINE CADDY
ра
CADDY RETAINER
SPINE FREED
FROM LATCH
ASSEMBLY
CADDY LOCK
OEFEAT TAB
SPRING LATCH ASSEMBLY
Fig. 1-9. — Unload Operation
Removing the loaded caddy slowly, the sweeper arm swings
under the stylus into a "cocked" position (Fig. 1-10). Spine sense
switches S6 and S8 are opened. As the loaded caddy continues to
be removed slowly, the left receiver pad cam begins to rise. As it
rises it activates stylus clean switch S7, causing the stylus to be
lowered onto the stylus sweeper arm pad. There is an idle taper to
the left receiver pad cam. The stylus is being lowered onto the
sweeper arm pad during the time the caddy is travelling along the
idle taper. When the caddy reaches the end of the idle taper. the
left receiver pad cam reaches a point where, through mechanical
linkage, the sweeper arm is released from its "cocked" position
wiping the dirt from the stylus. At the same time. stylus clean
switch S7 opens allowing the stylus lifter circuit to lift the stylus
back up into the stylus cartridge for protection.
CADDY
SLIDE GUIDES
ЖА
SWEEPER
ACTUATING CAM SE
Fig. 1-10. — Sweeper Operation
After the loaded caddy has been removed it may be turned over
and the player re-loaded to play the other side of the VideoDisc.
DO NOT leave the player in the "load" mode for any extended
period of time. Dust or other contaminates could enter the
mechanism through the open caddy entry port door and cause
damage to the unit.
Off Position
Placing the FUNCTION lever in the "off" position opens AC
Power switch S2. This will interrupt the AC input power to the
player, the turntable will not rotate and the B- supplies to the
electronic circuits will be disabled. A spring on the antenna
Switch switches the RF output connector back to the external TV
antenna connection when the FUNCTION lever is placed in the
"Off" mode.