Matsui 1410R, Service Manual

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- I2C bus (pins 49 and 50): The microcontroller is connected to non-volatile memory IC7685 (EEPROM)
via bus I2C. Personal preferences (PP) and channel data are stored in the memory. The system can store
79 channels (with the data on tuning voltage and band) and personal preference.
- Service (pin 7): If this pin is connected to earth when the set is switched on, the unit will go into Service
Default Mode (see Repair Facilities in chassis CTN Service Manual).
- Options (pins 14, 21, 52): While start up, the microcontroller checks option pin voltages to know the
special features of this chassis. This one is implemented changing the associated components of these
pins. Different options (menu, multistandard, etc. ) can be seen on tables of diagram E.
- Multistandard out-puts (pins 46, 47, 48): These signals are only used on multistandard units, for
switching the system for decoding sound and video. Signals from pins 46 and 47 are inverted and
set at the correct level by transistors 7672 and 7673, respectively. After they are inverted together
with the signal from pin 48, they make up the system status lines: BG/I is high for Pal I system, BG/
L is high for L and L’ systems and L/L’ is high for L’ system.
- OSD synchronization (pins 36, 37): In order to synchronize the OSD and the TXT information with the
picture signal, the VERT FLYBACK signal (pin 37) and HOR FLYBACK signal (pin 36) are added in inverted
form to the integrated circuit. Due to this if the video signal is lost, the TXT keeps synchronism. - Video
inputs (pins 23 and 24): These inputs are only used on TXT sets. The teletext information is extracted from
the video signal inserted on pins 23 (internal video) and 24 (external video), depending on status of INT/
EXT (pin 8).
- Oscillator (pins 41 and 42): A 12-MHz. oscillator is determined by a 12-MHz. crystal between pins 41 and
42.
- Tuning (pins 1, 9, 16, 51): The unit has a VST (Voltage Synthesized Tuning) system. This system works by
tuning to a station on the tuner through a linear variation of the tuning voltage (V-VARI) from 0V. to 33V.
applied on pin 2 of the tuner. It is generated on pin 1 of the uP and converted to an adequate level for the
tuner using T7605. The AFC signal (Automatic Frequency Control) of IF detector is added to the tuning
voltage V-VARI by R3689 and R3688 to compensate for the slow variation of the tuning feature.
While searching for the station, pin 51 is set on high, which means that the AFC voltage will not be added to
the V-VARI. If an IDENT signal is received on pin 16 while searching for a station, the uP stop searching and
checks via input pin 9 if the tuning is correct and whether the AFC signal can be activated again.
- AGC auto tuning (pin 30): This pin is used to limit the AGC voltage in automatic tuning so that noise
signals are not memorized.
- Band switching (pins 15, 17, 18): There are 3 outputs for band switching pin 15 for VHFI, pin 17 for VHFIII
and pin 18 for UHF. The uP controls the channel band in the tuner by a voltage of +5V. at the correspondent
output.
- Picture and sound adjustments (pins 2, 3, 4, 5, 6): Volume control (pin 2), brightness control (pin 3),
colour control (pin 4), contrast control (pin 5), and sharpness control (pin 6).
The RC networks are used to convert the modulated pulse output to a DC voltage level. These settings can
be pre-programmed in the memory as a personal preference (PP). Mute is controlled internally on the up
during automatic station search or when the signal received is interrupted (detected via the IDENT signal on
pin 16).
- INT/EXT (pin 8): When this output is 0V. the set is switched to external via transistor (7877). This signal is
added to the signal from pin 8 of Euroconnector, so that either of them can be used to switch to external. This
line is also used by the microcontroller as an input line, to switch the adequate video input (internal or
external) used for decoding TXT.
- Standby (pin 19): When this output is high, the set is switched to stand by. The start-up voltage of the
TDA8361A (pin 36) is reduced and the line oscillator stops.
- Fast blanking (pin 35): This pin is used for delete the video picture signal while RGB insertion is produced.
- NIL (Pin 27): This control signal is used (only on TXT sets), to eliminate interlacing for TXT signals. It is
applied to the vertical deflection by switching transistor 7640.
- RGB outputs( pins 32, 33, 34): The RGB outputs are used for On-Screen Display (OSD) and also for
TXT (TXT character set is used for both functions). RGB signals are applied trough common base amplifiers
(7641, 7642, 7644) to RGB outputs of 7015 (pins 20, 19, 18).