CIRCUIT
18
3. PB MODE
(1) Signal Flow
FM signal input to the Pin 13rd is amplified, and ditributed to the two BPFs-1.4MHz and 1.8MHz (NTSC Case: 1.3MHz
& 1.7MHz). The band passed FM signals are supplied to the De-Modulator unit. First, the FM LIM confines the FM to
the limitted level, and then the signals are demodulated. The converted audio signals are compensated by the SW
NOISE COMPEN. The signals are passed by the LPF, and de-emphasized by the FM DE-EMPH in order to restrict
the FM back-noise. The PNR processor expands the signals and reduces the audio noise.
The two Line AMPs amplifiy the audio level, and supply to the Audio Out Pin 30th, 29th. The Mod out Pin 27th is and
mixed audio output port for the RF-modlator. The Output SW is available to select the audio output of Left+Right
(Stereo), Left only, Right only and Normal Audio. The Pin 26th is the input port for Normal audio.
(2) Noise Compensation and Hi-Fi Detect
In the Hi-Fi audio system, the noise trouble occurs, when the FM signal is defective. The defection of FM signal is due
to the Drop Out which is scratched on the surface of tape, and the audio SW noise. If the D.O.DET detects the Drop
Out of FM signal, it requires the HOLD PULSE GEN to generate the hold pulse, and then compensate the noise. And
the HOLD PULSE GEN generates the regular pulse by the Audio SW pulses, then send the control signal to the SW
NOISE COMPEN which compensates the noise.
The ENVE/HiFi discreminates the Hi-Fi audio from the Normal audio. If the envelope of FM Hi-Fi exists, “High”-5V-
control signal is out to the Pin 14th. Otherwise Control voltage is 0.
13
14
30
27
29
26
LPF
8
FM
LIM
DEMOD
D.O.
DET
HOLD
PULSE GEN
SW NOISE
COMPEN
LPF
LPF
PNR
PNR
LPF
FM
LIM
DEMOD
SW NOISE
COMPEN
FM
ALC
AMP
FM PB IN
Hi-Fi DET
AUDIO OUT(L)
AUDIO OUT(R)
NORMAL AUDIO
A SW
PULSE
MOD OUT
AMP
AMP
ENVE/
HiFi
OUTPUT
SW
FM
DET
FM
DE-EMPH
FM
DE-EMPH
Summary of Contents for DV-K*84W Series
Page 71: ...CIRCUIT DIAGRAMS 68 SECTION 9 CIRCUIT DIAGRAM 9 1 CONNECTION DIAGRAM DV K884W K484W K284W...
Page 72: ...CIRCUIT DIAGRAMS 69 9 2 POWER CIRCUIT DIAGRAM DV K884W K484W K284W...
Page 73: ...CIRCUIT DIAGRAMS 70 9 3 SYSCON AND LOGIC CIRCUIT DIAGRAM...
Page 74: ...CIRCUIT DIAGRAMS 71 9 4 PIF CIRCUIT DIAGRAM DV K884W K484W K284W...
Page 75: ...CIRCUIT DIAGRAMS 72 9 5 IF MPX MODULE CIRCUIT DIAGRAM DV K884W K484W K284W...
Page 76: ...CIRCUIT DIAGRAMS 73 9 6 VIDEO AUDIO CIRCUIT DIAGRAM DV K884W K484W K284W...
Page 77: ...CIRCUIT DIAGRAMS 74 9 7 Hi Fi PRE AMP CIRCUIT DIAGRAM DV K884W K484W K284W...
Page 78: ...DISASSEMBLY 79 SECTION 11 DISASSEMBLY 11 1 PACKING ASS Y...
