Akai 29CT24FS, Service Manual

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SERVICE MANUAL
3) Basic Structure
3.1) Internal Connections
TMPA8827 has two pieces of IC chip in one package, using Multi-Chip-Package (MCP) technology.
One is a micro controller (MCU) and the other one is a signal processor (SP) for a color TV. There
are some internal connections between these two ICs for handling below signals.
Table 6 Signal Name Direction Description
No.
Signal Name Direction Description
1 SCL M to S Internal IIC bus SCL
2 SDA Bi-direction Internal IIC bus SDA
3 OSD R M to S OSD signal connection
4 OSD G M to S OSD signal connection
5 OSD B M to S OSD signal connection
6 OSD Y/BL M to S OSD display control
7 OSD I, CS OUT M to S OSD half-tone control/Test pattern signal
8 C-Video S to M Composite video signal from internal video switch, for CCD
9 C-Sync S to M Composite sync. signal from sync. Separator, for CCD
10 HD S to M Horizontal timing pulse regenerated from FBP, for OSD
11 VD S to M Vertical timing pulse from sync. Separator, for OSD
12 CLK M to S 8 MHz clock
13 AV
DD
M to S Reference voltage for C-Video interface
14 ADC S to M A/D converter monitoring RF-AGC, R-Y and B-Y
Functions of SP from MCU are controllable through the IIC bus of the internal connections.
3.2) Power Supply
TMPA8827 has some power supply and GND pins. Power supplies related MCU must be applied at
the first. Power supplies for H.VCC and TV D.VCC are the second with at least 100 ms delay after
MCU power ON. The other power supplies are the last, which are recommended to be supplied from
a regulator circuit using FBP.
3.3) Crystal Resonator
TMPA8827 requires only one crystal resonator, in stead that a conventional two-chip solution
requires two resonators at least, one for MCU and the other one for SP. An oscillation clock with the
crystal resonator of TMPA8827is supplied for MCU operation, PIF VCO automatic alignment,
alignment free AFT, chroma demodulation and horizontal oscillation. The oscillation frequency is
very important so that those of functions work properly, so that designing the oscillation frequency
accurately is required. The spec of crystal is recommended to be within
fosc: 8 MHz +/-20 ppm
ftemp: 8 MHz +/-40 ppm (-20°C to +65°C)
While RESET of MCU is active, the MCU function stops. Hardware and software initialization
sequence including power supplies control is required, because status of any hardware after the
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