Toshiba CN27E90 Technical Training Manual page 21

3-1-4. Audio Multiplex Demodulation Circuit
The sound multiplex composite signal FM-detected in the
PIF circuit enters pin 12 of HIC (hybrid IC) in passing
through the separation adjustment VR RV2 and amplified.
After the amplification, the signal is split into two: one enters
a de-emphasis circuit, and only the main signal with the L-
R signal and a SAP signal removed enters the matrix circuit.
At the same time, the other passes through various filters and
trap circuits, and the L-R signal is AM-demodulated, and the
SAP is FM-demodulated.
Table 2-1 Matrix for broadcasting conditions and
reception mode
Broad- Switching
12 pin 14 pin
casted mode
(R)
Stereo STE R
SAP R
MONO L+R
Mono STE L+R
SAP L+R
MONO L+R
Stereo STE R
+ SAP SAP
SAP MONO L+R
Mono STE L+R
+ SAP SAP
SAP MONO L+R
M V U S 3 2 S
M P X
O u t
9
Monitor the input
Stereo 0V
pin for multiplex
sound IC
Other
Fig. 2-5 Block diagram of MVUS32S
Output OSD display
Stereo SAP
(L)
L O X
L O X
L+R O X
L+R X X
L+R X X
L+R X X
L O O
SAP O O
L+R O O
L+R X O
SAP X O
L+R X O
Then, both are fed to the matrix circuit. At the same time,
each of the stereo pilot signal fH and the SAP pilot signal 5fH
is also demodulated to obtain an identification voltage. With
the identification voltage thus obtained and the user control
voltage are used to control the matrix.
The audio signals obtained by demodulating the sound
multiplex signal develop at pin 10 and 11 of HIC and develop
the terminals of 12 and 14 of the module.
T V D A C - o u t 1
(SURR OFF)
R-Out
11
10 12
SAP 0V
Other 0V
0V
N o t u s e d f o r
C N 3 2 E 9 0 .
TV waveform detection
output (R)
T o A V s e l e c t c i r c u i t
Note:
Of the mode selection voltages, switching voltages for STE,
SAP, MONO do not output outside the module.
They are used inside the module to control the BUS.
21
T V D A C - o u t 2
(RFSW)
L - O u t
14
13 14
OFF 0V
RF1 0V
ON 9V
RF1 9V
TV waveform detection
output (L)