Audio Power Amplifier, Ica1; Headphone Amplifier, Ica3 - Hitachi CP2896TA Wartungshandbuch

6
The pin functions of the Sound
Processor:
Pin I / O Short description
04 O DSP reset and off by low
05 O Subwoofer off by high
07 I Supply voltage +5 Vr
09 I I2C clock (SCL)
10 I/O I2C data (SDA)
11 O I2S clock
12 I/O I2S word select
13 O I2S data output
14 I I2S1 data input
18 Digital power supply +5Vr
19 Digital ground
20 I I2S2 data input
24 I MSP power-on-reset by low
25 O Headphone output, R
26 O Headphone output, L
28 O Loudspeaker output, R
29 O Loudspeaker output, L
31 O Subwoofer output
33 O Scart output, R
34 O Scart output, L
36 O Scart output, R
37 O Scart output, L
38 Volume capacitor (Hp amp)
39 Analog power supply +8.0V
40 Volume capacitor (Ls amp)
42 Analog ref V, high V part
43 I Scart input, L
44 I Scart input, R
46 I Camera input, L
47 I Camera input, R
49 I Scart input, L
50 I Scart input, R
52 I Scart input, L
53 I Scart input, R
54 Ref voltage IF A/D conv
55 I Mono input
57 Analog power supply +5Vr
58 I IF input 1
59 I IF input common
60 I IF input 2 (Tuner SIF)
62 I Crystal osc 18.432 MHz
63 O Crystal osc

Audio Power Amplifier, ICa1

The audio signal is amplified using the TDA2616 dual chan-
nel hi-fi Audio Power Amplifier. The amplifier has a built-
in protection system against short circuits and thermal
overloads. It also has an internal input mute circuit that
silences unwanted signals at the inputs when the TV set is
switched on or off.
Audio signals from the audio processor are fed to pins 1
(L) and 9 (R). A logical low on pin 2 mutes the amplifier.
The mute control signal is taken from the microcontroller
(pin 51) via transistors ta10, ta4 and ta3. A high level on
microcontroller pin 51 causes a so-called "central mute",
which means that each of the audio power amplifiers are
muted.
The supply voltage +28 V is taken from the power supply
to pin 7. The amplified audio signals for the loudspeakers
are output on pins 4 (L) and 6 (R). The impedance of the
internal loudspeakers is 8 ohm and the minimum imped-
ance of external speakers is 8 Ohm. When an external
speaker is used, the internal speaker is muted by a switch
in the speaker connector.

Headphone Amplifier, ICa3

Audio signals from the sound processor are fed to the in-
verting input pins 2 (L) and 6 (R). Outputs to the headphone
connector are from pins 1 (L) and 7 (R). There is a switch in
the headphone connector that informs the microcontroller
(pin 1), that headphones are connected. The headphone
volume control then appears in the OSD in addition to the
loudspeaker volume control.