Technicolor - Thomson ICC19, Принципы и обслуживание

Страница: 140 / 169

AUDIO POWER AMPLIFIER, IA001
The audio power amplifier consists of a single integrated circuit, IA001
(TDA7269). This is a B-type amplifier. It has a symme14 V/-14 V power
supply.
The speaker output impedance is 8 W for a 2 x 10 W sinusoidal power output.
IA001 MUTE
Pin 5 of IA001can switch off the sound if it is at a potential of +US. In normal
operation, the voltage at this pin is close to 5 V due to the saturation of
Transistor TA002.
BOOMER POWER AMPLIFIER, IA002
This amplifier receives audio signals G and D mixed on Input 7 via a low-pass
filter. The pass band of this amplifier is from 20 to 500 Hz.
IA002 MUTE
Pin 3 of IA002 can switch off the sound if it is at a potential of -US. In normal
operation, the voltage at this pin is close to 8 V due to the saturation of
TA001.
INTERLOCK
In the event of an overload on the +US power supply line, TP190 saturates
and leads to the saturation of TP170. In the event of an overload on the -US
line, the negative voltage (-5 V) on the anode of DP150 becomes positive,
and leads to the conduction of TP170. In both cases, the voltage at 28 of
IV001 goes to 0. The time base and regulation commands disappear. The TV
shows an error code. The red LED flashes.
INTERLOCK WITH DOLBY OPTION
In the event of an overload on the +US power supply line, the voltage drop at
the terminals of Resistor RP130 increases and leads to the conduction of
Transistor TP129. Transistor TP170 is then saturated. The voltage at 28 of
IV001 goes to 0. The time base and regulation commands disappear. The TV
shows an error code. The red LED flashes.
CENTRE DE
FORMATION TECHNIQUE
137
137