JBL JSR 400 Service Manual ▷ View online
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Dolby Pro-Logic
Ò
A/V Receiver
JSR-400
CIRCUIT DESCRIPTION
1. Surround Circuits
This model incorporates a surround processor circuit.
Fig. 1 is a block diagram of the surround processor circuit. The microprocessor transfers the data to the Dolby Pro-Logic
decoder and Time Delay Device to operate the circuits in each mode.
1) BYPASS
Set to this mode to listen to ordinary stereo sound. The rear L/R and center outputs will be muted.
Set to this mode to listen to ordinary stereo sound. The rear L/R and center outputs will be muted.
Input
Auto-
balance
Control
X1
X1
IC10
NJW1102
AMP
AMP
C
S
C
S
electric
vol.
Center/
Operating
Mode
Control
Adaptive
Matrix
By-Pass Line
L
R
C
S
S
S
V
LR
V
CS
IC11
NJU9702
Time
Delay
7knz
LPF
Modified
Dolby B NR
Noise
Generator
Noise
Sequencer
IC5
LC4966
Buffer
Buffer
L Input
R Input
MASTER
VOLUME
TONE
CONTROL
TONE
CONTROL
L
C
R
S
AMP
AMP
AMP
AMP
SPEAKER
FRONT L
CENTER
FRONT L
SURROUND L
SURROUND L
Fig. 1
Block diagram of the surround
processor circuit
SURROUND
SURROUND
IC5
OUTPUT
OUTPUT
SOURCE
SOURCE
L
R
LC4966
Fig. 2
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Dolby Pro-Logic
Ò
A/V Receiver
JSR-400
2) DOLBY PRO-LOGIC CIRCUIT
Dolby Pro-Logic is a sound effect system for movies developed by the Dolby Laboratories Licensing Corp. IC10 (NJW1102) is
Dolby Pro-Logic is a sound effect system for movies developed by the Dolby Laboratories Licensing Corp. IC10 (NJW1102) is
a Dolby Pro-Logic decoder IC. When an audio signal recorded using the Dolby Pro-Logic system is sent to this IC, the left,
right, center and surround components are separated. The surround signal component is delayed by the delay IC11
(NJU9702). Fig. 3 shows the configuration of the Dolby decoder.
With Dolby Pro-Logic, three center modes depend on the use of a center speaker as follows.
NORMAL:
Bass frequencies are sent only to the Left and Right Front channels. Select this mode when the
Center Speaker is smaller than the left and Right speakers.
WIDE:
Bass frequencies are sent to the Left, Center and Right speakers. Select this mode when the
Center speaker is approximately the same size as the Left and Right speakers.
PHANTOM: Center channel information is sent to the Left and Right speakers. Select this mode when you do
not have a center channel speaker.
3) STEREO CIRCUIT
In 3-stereo mode, surround sound is sent to front Left channel and front Right channel and no surround sound is sent to
In 3-stereo mode, surround sound is sent to front Left channel and front Right channel and no surround sound is sent to
surround channel.
L-ch
L-ch
R-ch
R-ch
C-ch
C-ch
Input
Auto-
balance
Control
X1
X1
Audio
Signal
Audio
Audio
Signal
IC10
AMP
AMP
C
S
C
S
electric
vol.
Center/
Operating
Mode
Control
Adaptive
Matrix
By-Pass Line
L
R
C
S
S
S
V
LR
V
CS
IC11
NJU9702
Time
Delay
7knz
LPF
Modified
Dolby B NR
Fig. 3
Flow of signals within the system
in the Dolby Pro-Logic mode
Adaptive
Matrix
Center/
Operating
Mode
Channel
L-ch
L-ch
R-ch
R-ch
C-ch
L
R
C
R
C
C
electric
vol.
Input
Autobalance
Control
IC10 NJW1102
X1
X1
Audio
Signal
Audio
Signal
Fig. 4
Flow of signal within the system in the 3-stereo mode
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Dolby Pro-Logic
Ò
A/V Receiver
JSR-400
4) TEST TONE GENERATOR
The test tone generator generates a test tone (noise) to check the balance of sound output from each speaker in the Dolby
The test tone generator generates a test tone (noise) to check the balance of sound output from each speaker in the Dolby
Pro-Logic mode. (This circuit is produced under license of the Dolby Laboritories Licensing Corp.) The test tone to the
loudspeakers at 2 second intervals in the following sequence: Left, Center, Right, Rear (both rear channels).
2. DIGITAL TUNING SYSTEM DESCRIPTION.
1) DIGITAL TUNING SYSTEM
FM FRONT END PACK
FM ANT
AM ANT
FM RF
AM RF
FM MIX
AM MIX
FM OSC
AM OSC
BUFFER
BUFFER
FM PLL Loop
AM PLL Loop
Low Pass Filter
Q201, 202
FM IN
AM IN
IC2
PLL Prescaler
CPU
IC1
Data
FL
Display
Key
Switch
Matrix
Adaptive
Matrix
Noise
Sequencer
Input
Auto-
Balance
Control
S
IC11
NJU9702
Time
Delay
IC10 NJW1102
L
B
C
B
C
S
Center/
Operating
Mode
Channel
L-ch
R-ch
C-ch
S-ch
Noise signal output
Fig. 5
Flow of noise signals within the system
1 6
Dolby Pro-Logic
Ò
A/V Receiver
JSR-400
2) VCO VS. FM BAND FREQUENCY CURVE.
3) VCO VS. AM BAND FREQUENCY CURVE.
87.5 89.5 91.5 93.5 95.5 97.5 99.5 101.5103.5 105.5 107.5
V
Voltage
(V)
CO
8
7
6
5
4
3
2
1
0
FM Band Frequency (MHz)
520 600 700 800 900 1000 1100 1200 1300 1400 1500 1600
V
Voltage
(V)
CO
9
8
7
6
5
4
3
2
1
0
AM Band Frequency (kHz)
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