Service manual

All MSP versions contain digital audio processing used for the basic left/right stereo
sound, such as bass, treble, balance, incredible sound and spatial. In addition to that,
the MSP3451 is also able to perform Virtual Dolby; a Dolby approved sound mode for
surround sound reproduction with left/right speakers only.
The MSP3451 is capable of supporting four stereo inputs. Therefore, an extra input
selector (HEF4052) is not needed. It has a separate headphone output, so sound
control is done separate from the speakers.
Audio Decoding
The signal is fed to the AGC. After this, an ADC converts the IF-signal to a digital signal.
This digital signal is processed by two demodulation channels. The first one is able to
handle FM.
This channel contains a mixer to shift the incoming signal in the frequency domain. This
shift is determined by the value of a DCO (Digital Controlled Oscillator).
After the down-mix, the signal is fed, via a filter, to a discriminator. From here the FM
(BTSC) demodulation can be performed.
Both channels contain an 'automatic carrier mute' function, which automatically mutes
the output of the analogue section when no carrier is detected.
After demodulation, the FM-signals are subjected to a de-emphasis operation. After
that, the matrix of the stereo system is applied.