Akai LTA-26C903 Service Manual page 22

The mono intercarrier sound circuit has a selective FM-PLL demodulator which can be switched to the
different FM sound frequencies (4.5/5.5/6.0/6.5 MHz). The quality of this system is such that the external
band-pass filters can be omitted. In the stereo versions of UOCIII the use of this demodulator is optional
for special applications.
Normally the FM demodulators of the stereo demodulator/decoder part are used (see below).
●The FM-PLL demodulator can be set to centre frequencies of 4.72/5.74 MHz so that a second sound
channel can be demodulated. In such an application it is necessary that an external bandpass filter is
inserted.
●The vision IF and mono intercarrier sound circuit can be used for the demodulation of
FM radio signals. With an external FM tuner also signals with an IF frequency of 10.7
MHz can be demodulated. For the QIP90 versions this is valid only for the "stereo"
versions
●Built-in adaptable brightness delay circuit
●switchable brightness signal transmission rate
Pin Description：
Pin
1,2,12,18,28,40
68,81,89,92,95,101
121,125
3,4,45,69,82,88,90,
91,93,94,96,100,
110,117,118,124
5
6
7
8
9
10
11
13
14
15
16
17
19
20
21
22
23
24
25
27
29
30
31
Name
VSS,GND
VDD
VREF_POS_LSL
VREF_NEG_LSL+HPL
VREF_POS_LSR+HPR
VREF_NEG_HPL+HPR
VREF_POS_HPR
XTALIN
XTALOUT
VGUARD/SWIO
DECDIG
VP1
PH2LF
PH1LF
SECPLL
DECBG
EWD/AVL
VDRB
VDRA
VIFIN1
VIFIN2
IREF
SIFIN1/DVBIN1
SIFIN2/DVBIN2
AGCOUT
Description
ground
Power supply
SDAC input signal
Crystal oscillator input
Crystal oscillator output
V-guard input / I/O switch
decoupling digital supply
decoupling digital supply
phase-2 filter
phase-1 filter
SECAM PLL decoupling
bandgap decoupling
East-West drive output or AVL capacitor
vertical drive B output
vertical drive A output
IF input 1
IF input 2
reference current input
SIF input 1 / DVB input 1 SIF
tuner AGC output
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