Service manual

CA-25
Audio Development
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
2425
36
26
27
28
29
30
31
32
33
34
35
37
38
39
40
41
42
43
44
45
46
47
48
BASSL2
TRE-R
TRE-L
SURRIN
SURROUT
LSOUT-R
LSOUT-L
NC
SDA
SCL
DGND
SAD
MAININ
MAINOUT
NC
PCINT1
PCINT2
PLINT
COMPIN
VGR
IREF
GND
SAPTC
VCC
BASSL1
BASSR2
BASSR1
SURRTC
TVOUT-L
TVOUT-R
AUX2-L
AUX2-R
AUX1-L
AUX1-R
VLTC
VLDC
VCAWGT
VCATC
VCAIN
VEOUT
VETC
VEWGT
VE
SAPIN
SAPOUT
NOISETC
STIN
SUBOUT
IC1400
C1401M
C1402M
C1404M
C1416
C1435M
PROV
C1434M
PROV
R1401
R1402
R1425M
C1421
C1420
R1406M
C1418
C1436
C1413
R1404M
C1425
R1421M
R1422M
+9VSW
C1433M
C1430
C1403M
C1406M
C1431M
C1409
C1410
R1412
R1413
R1409M
C1432
C1415
C1414
R1405M
C1417
C1427
C1426
C1428
C1419
C1422
C1424
R1407M
R1408M
External
Audio In
Composite
AudioInFrom
ICX2200, Pin 2
Clock &
Data Lines
To Audio &
External Amps
MTS Processing
For MTS chassis, IC1400 serves as the sound processor. It features mono, stereo, or SAP settings. It
also features adjustable bass and treble levels, balance adjustment, sound-right audio limiting, front surround
sound, and speaker cut-off. Furthermore, whereas internal and external source switching is accomplished
by a separate switching IC for the stereo sets, the MTS is capable of internally switching between various
sources.
<<Figure CA-24>>
IC1400 is powered by the +9VSW at pin 24. Composite audio enters through C1436 at pin 19. This
signal is reduced by a voltage divider consisting of R1421M and R1422M. I
2
C bus control (serial clock
and data) from the microprocessor enters the MTS processor at pins 9 and 10. Information on these lines
controls those adjustments as described above as well as the volume. Right and left channel auxiliary input
feeds into pins 39 and 40. Audio outputs come from pins 6 and 7 and feed the amplifier circuit in the
manner described above.