Explanation Of Each Part; Block Diagram - Panasonic Technics SL-1600M Service Manual

Explanation of each part

1. B.F.G.
METHOD
FORCE FREQUENCY GENERATOR)
Making use of the back electromotive force that is
generated in the drive coil winding of the motor as a
frequency generator, the frequency of the frequency
generator is converted to the number of revolutions for
the turntable.
After shaping the wave form of this back electromotive
force, it is composed logically, and a frequency is
generated that is proportional to the number of revolu-
tions. This is the use of the B.F.G. Making use of the
drive coil winding, frequency generator coil windings
and magnets are not necessary, yielding a motor struc-
ture that is very compact.
2. FREOUENCY-VOLTAGE CONVERSION CIRCUIT
Being composed of a trapezoidal wave generating circult.
a pulse generating circuit and a sampling integration cir-
cuit, the B.F.G. output frequency is converted to a vol-
tage, and control output voltage is generated in order to
maintain the rotational speed of the turntable at a cons-
tant level.

Block diagram

(BACK ELECTROMOTIVE
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3. OPERATION CONTROL CIRCUIT
The operation control circuit functions as a control out-
put voltage control keeping the rotational speed of the
turntable constant with regard to the start of turntable
operation and the operation of the mechanism. With
this circuit, transient response characteristics and start-
ing characteristics are very good.
4. OPERATIONAL AMPLIFIER (OP AMP) ACTIVE
FILTER
Because of using an operational amplifier in the active
filter, an ideal filter operation is possible.
As a result, such high performance as a signal-to-noise
of 0.03% (WRMS) have been achieved.
5. DRIVE CIRCUIT
By incorporating a large copacity power transistor in the
integrated circuit, a starting torque of 1 kg-cm can be
obtained. By means of this large starting torgue, prompt
starts have been realized.
6. THREE DIFFERENTIAL SWITCHING CIRCUITS
By means of the signal from the position signal coil, the
starting circuit power transistor
obtaining smooth rotation.
selector operates,