Service manual

CA-24
CA CIRCUIT DESCRIPTIONS
<<Figure CA-23>>
IC1402 is powered by the +18AUD at pin 4. Pins 5 and 8 receive the audio input, while the output for
right and left channels come from pins 1 and 3 respectively. This volume IC is controlled by a DC level
from pin 46 of the microprocessor. Pin 46 emits a pulse width modulated signal that is rectified and
smoothed by D1401, R1420M, and C1438. The resulting DC voltage is applied to pin 7 of IC1402. This
voltage will vary from +0.5 to +5 volts DC. The gain of this IC is 12dB.
IC Location Part # Notes
IC804 221-00598-01 All Models
IC1400 221-01127 MTS Models
IC1400A 221-01382 Stereo Models
IC1401 221-01171 Stereo Models
IC1402 221-01380 Stereo Models
<<Table CA-4>>
12
11
10
9
8
7
6
5
4
3
2
1
CH-2
CH-1
IC1401
+9VSW
1
2
3
45
6
7
8
IC1402
C1423
C1437
+18AUD
R1417
ZD1405
C1439
C1455
J1406M *
C1456
C1429
J1407M *
C1438
R1420M
R1419M
R1418M
+5VSBF
D1401
R1418
R1413
R1412
C1409
C1410
L R
Audio Output
to IC804
* For Stereo Chassis
excluding 9-2064, 2065
Provisional on 9-2064, 2065
Audio Switch
Pin 44, IC6000
External Audio
from Jack Pack
Left & Right
Stereo Audio
(Pins 1,2, IC1400A)
Volume Control
Pin 46, IC6000