Toshiba TW40F80 Audio Multiplex Demodulation Circuit, 2 Block diagram of MVUS34S, Broad, Output

1-3. 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 en- ters a de-emphasis circuit, and only the main signal with the L-R signal and a SAP signal removed enters the matrix cir- cuit. At the same time, the other passes through various fil- ters and trap circuits, and the L-R signal is AM-demodu- lated, and the SAP is FM-demodulated.

MVUS34S

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 mul- tiplex signal develop at pin 10 and 11 of HIC and develop the terminals of 12 and 14 of the module.

MPX			TV	DAC-out1	TV	DAC-out2
Out			R-Out (SURR ON/OFF)		L-Out	(RFSW)
9	10	11	12	13	14	15

Monitor the input pin for multiplex sound IC

Stereo 0V

Other 5V

SAP	0V
Other	5V

OFF	0V
ON	9V

RF1	0V
RF2	9V

TV waveform detection	TV waveform detection
output (R)	output (L)

To AV select circuit

Fig. 2-2 Block diagram of MVUS34S

Table 2-1 Matrix for broadcasting conditions and reception mode

Note:

Of the mode selection voltages, switching voltages for STE, SAP, MONO do not output outside the module.

Broad-	Switching	Output		OSD display
		12 pin	14 pin
casted	mode			Stereo	SAP
		(R)	(L)
Stereo	STE	R	L	•	–
	SAP	R	L		–
				•
Mono	MONO	L+R	L+R	•	–
	STE	L+R	L+R	–	–
	SAP	L+R	L+R	–	–
	MONO	L+R	L+R	–	–
Stereo	STE	R	L	•	•
+	SAP	SAP	SAP
				•	•
SAP	MONO	L+R	L+R	•	•
Mono	STE	L+R	L+R	–	•
+	SAP	SAP	SAP	–
					•
SAP	MONO	L+R	L+R	–
					•

They are used inside the module to control the BUS.

•: Available, – : Not available

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