Technicolor - Thomson ICC19, Принципы и обслуживание

Страница: 22 / 169

SWITCH-ON PROCEDURE
The 10VSTBY from the power supply is used. This is limited to 5 V by a Zener
diode inside the IV001, and powers its IIC1 bus interface.
After its power supply, clock, and reset, the IR001 microcontroller manages the
following commands:
• RAM reading,
• I/O configuration of ports,
• Reading EEPROM, IR003. To be programmed, if necessary, using the default
values contained in the IR002 program memory, if it is deprogrammed or
blank.
When an ON command is issued, the IR001 microcontroller initialises IV001
via its IIC1 bus with values stored in the EEPROM (loading of essential
parameters: on, geometry, etc.). Pin 24 on the IV001 is freed, and leads to the
presence of VCC1 = 8 V via TV002. This voltage powers Pins 22 and 44 of the
IV001.
The line time base, secondary regulation, and frame time base are gradually
powered up by the slow-starting capacitor, CV246 (Pin 17 of IV001).
The rising of the line 13 V transmitted by DR104 confirms that the On function
is fully established (5V at Pine 65 of IR001). This 13VL also makes it possible
to obtain a +5V via the IP140 regulator.
The ICUT signal (Pin 43 of IV001) indicates when the tube is warmed up, and
frees the analogue controls. The image and sound appear. Orders routed in
from the outside, e.g. from the keypad or the remote control unit, are then
processed.
FRONT PANEL LED CONTROL
In Standby Mode, Pin 51 of microcontroller IR001 is in high impedance.
Switching transistor TR002 powers the red LED from the 5 V STBY.
In On Mode, the 13 V from the line time base powers the green LED. This is the
initialisation phase, and results in the indicator lamp glowing orange.
When the warm tube signal, sent by the I2C1 bus to IR001, is detected, Pin 51
of IR001 goes to 0. This blocks TR002 and cuts off the power supply to the red
LED.
CENTRE DE
FORMATION TECHNIQUE
19
19