JVC KD-D30 - Safety Precautions

These curves, showing the maximum low-level boost im-
parted by both C-type and B-type noise reduction in the
absence of high frequency signals, illustrate some of the
similarities and differences between the two systems.
Dolby C noise reduction imparts more boost in recording
and more cut in playback, thus providing more noise reduc-
SIDE-CHAIN OF
FROM INPUT
STAGES
SPECTRAL
SKEWING
DOLBY
SIDE-CHAIN OF
LOW-LEVEL
STAGE
FROM PLAYBACK ANTI.
PRE-AMPLIFIER
HIGH-LEVEL
ie STAGE f
SATURATION
NETWORK
KD-D30 A/B/C/E/J/U
tion. The effect also extends about two octaves lower with
C-type noise reduction to maintain subjectively uniform
noise level across the spectrum. Processing at very low fre-
quencies is not required with either system because low
frequency noise is insignificant in properly engineered
cassette recorders.
SIDE-CHAIN OF
LOW-LEVEL
STAGE
ANTI
SATURATION
NETWORK
TO RECORDING
AMPLIFIER
C-TYPE ENCODER
SIDE-CHAIN OF
HIGH-LEVEL
STAGE
OUTPUT
SPECTRAL
SKEWING
DOLBY C-TYPE DECODER
Fig.
4-B
Dolby
C-type
NR
block
diagram
Safety Precautions
A\Safety mark
Safety is very important with this unit. When replacing the
parts marked A\, be sure to use only those designated
parts. The designated resistors, diodes, transistors become
hot in use. When replacing, be sure to secure them with a
distance of more than 5 mm from the circuit board. In addi-
tion, they are banded together to avoid touching other wir-
ing, recheck this point as well after repair.
The wiring of the primary side should be wound more than
one and half times, then soldered.
poten
Minimum
5
mm
Minimum
5mm
To protect the circuit board
from carbonized under abnor-
mai condition.
Fig. 5
No. 4209