Prima PS-42D8 B Service Manual page 12

The block diagram of MSP3440 is as follows:
2, 3:SCL and SDA for the control of IC operation;
27,28:output to the right and left channel of sound power amplifier;
33,34:right and left channel of earphone sound;
36,37:AV OUT right and left channel of sound;
47,48:right and left channel of sound fed from main board;
50,51:AV IN right and left channel of sound;
53,54:right and left sound channel of sub-channel TV;
56,57:right and left sound channel of main channel TV;
67,69:SIF input of main and sub channel TV
Sound power amplifier TPA3001 is an amplification of mono-channel high efficiency D type power.
Under the condition of no heat dissipation its output power can be as high as 20 w. It has the functions of
over current and overheating protection. Automatic protection comes in when the input to the ground is
short-circuited. Then output is stopped. After the removal of short circuit, switch the set again and it
restores to normal. Therefore if the set becomes soundless due to the short circuit caused in carelessly
pulling out or plugging in the audio frequency wire (it is certainly not recommendable to do so), just
switch it on again and no big deal.
2.3.Picture and image:
Y signal of AV and SVHS shares the same channel. SVHS has priority. Identification of terminal S is
determined by electric level SID fed from SVHS socket to NM5. When the electric level of SID is of high
value, the system is identified as SVHS. Signals from TV or AV and YCRCB are altogether fed into
digital decoder VPC3230 (sent separately in two ways to N102 and N302). Channel switching is carried
out. They are decoded into 16bit CCIR601 signal to be fed into the processor of lower level for treatment.
VPC3230 mainly functions to switch over channels, separate Y/C of 4 lines, decoding of colors and
adjustment of picture effect.
2.3.1The block diagram of VPC3230 is shown below:
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