JBL JSR-400 Service Manual page 15

Dolby Pro-Logic A/V Receiver
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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
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).
Fig. 5
Flow of noise signals within the system
2. DIGITAL TUNING SYSTEM DESCRIPTION.
1) DIGITAL TUNING SYSTEM
FM ANT
AM ANT
IC10 NJW1102
Input
Adaptive
Auto-
Matrix
Balance
Control
S
Noise
Sequencer
FM FRONT END PACK
FM RF
FM OSC
BUFFER
AM RF
AM OSC
BUFFER
L
B
C
S
Time
Delay
IC11
NJU9702
FM MIX
AM MIX
L-ch
Center/
R-ch
Operating
Noise signal output
Mode
Channel
C-ch
S-ch
FM PLL Loop
AM PLL Loop
Low Pass Filter
Q201, 202
PLL Prescaler
FM IN
IC2
AM IN
Data
CPU
IC1
Key
FL
Switch
Display
Matrix
JSR-400
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