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7-4. CAPSTAN SERVO SYSTEM
As explained previously, the capstan servo controls the tape
speed in recording mode and the tracking in playback
mode.
This section covers the servo in recording mode, and the
ATF system which is unique to 8 mm video is dealt with on
the next page.
IC351
CXP80724
a:
0
(/)
z
w
(/)
....I
....I
<
I
I
l_j
I
a:
I
0
(/)
z
FG OUT
w
(/)
a:
FG OUT
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L - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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PW- 1 BOAD A3001
UNREG
POWER
DRIVE
S/S
1
2
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Fig. 7-4. Capstan Motor Drive Circuit
7-4-1 . Sensors and Amplifier
A magnetic resistance sensor (MR sensor) is used as the
rotation detection sensor for the capstan motor, so that a
384 - cycle sine wave can be obtained from each rotation.
The sensor output signal (CFG: Capstan Frequency
Generator) is amplified to the logic level by LB1 857 M
(IC361 ) , and i s then input to Pin @ . (Refer to Fig. 7-4.)
During recording, the motor rotates at approximately 3.1 82
rps in order to obtain a tape speed of 20.051 mm/s.
The CFG frequency at this time is 3. 1 82 x 384
LPF
5 V U N REG
IC361
LB1 857
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- 4-45 -
CP1 BOARD
1 - - - 1
CAPSTAN I
I I I
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1 222 Hz.
=
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I
MOTOR
I
I
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