3-3
Operation of tape drive system (PCBA Drive Control)
3-3-1
Servo circuit
Fig. 312 shows the block diagram of the servo circuit.
TPI9
RDY - - - ,
~--------~-----------------------------------E~
ENCODER
r -----,
r - - - - -
--R43lr
---,M;--------..,
I
II
~
II
~
I
IZV
I
, ,
II
,
f::\
I
ENCODER
I
I
....
MONO-
II'"
F
IV
.--
MOTOR
I
POWER
~ ~----;"I
--I
PRE AMP
I
I
TOR
MULTI
II
_
,~
DRIVE AMP I--T!-...,~I-{
TRANSISTOR
~L
___
~I
I
I,
f---4TPZO
I
II
r-
Tt-
U
I
I
I
START
S-LIM
,
,
CONTROL
,
.---+---~...,
,
HIS
I
I
~R.
:~OR.
I
RST
I .
I
HIS
-----------:-i
I
M
M
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ :..,1
.f
CLK
' -
.::::-.CLK
I
~
I
~
I
lOGIC
TENSION
I
CRI
CRZ
_
I
LOGIC
~
CONTROL
I
I
:
GO INT
I
6
c~
t-i,---+--..J
I
I
DIRECTION
FWD
I
CR8
LY~
_________
J
CONTROL
I '
CR7
REV
FWD
----------------------------------;-~
I
GO-----------------~~
I
LOK----------------------------------~~
~----------_;_I------------~~~T~Ma
LY~~&.9!L
______
J
Note: There is a model in which a fixed resistor is used as R43.
Fig. 312
Servo circuit block diagram
The
servo
circuit
consists
of
an
encoder
preamplifier,
comparator,
monostable
multivibrator,
F/V
converter,
motor
drive
amplifier,
start
controller, tension contorller, direction controller, and logic circuit for
controlling the above.
The output signal ,from the encoder, which is turned in contact with the
tape,
is amplified by the encoder amplifier,
and converted into a
pulse
signal by the following stage comparator.
The monostable multivibrator is
triggered by the output pulse signal of the comparator, and its setting time
is set nearly to
1/2
of the encoder output signal period.
Therefore, the
pulse duty of the output signal of the monostable multivibrator is approx.
- 317 -