![background image](http://html.mh-extra.com/html/panasonic/slsw850-port-cd-player/slsw850-port-cd-player_service-manual_261716016.webp)
2. Press the manual search button to check for smooth manual
search operations at either low or high speed (in both the forward
and reverse directions).
* Checking Playability
1. Play the 0.7 mm black dot and the 0.7 mm wedge on the
playability test disc (SZZP1054C) and verify that no sound skip or
noise occurs.
2. Play the middle tracks of the uneven test disc (SZZP1056C) and
verify that no sound skip or noise occurs.
9. Outline of 40-Second Sound Keeper Technique
Used for Prevention of Sound from Skipping
9.1. Conventional Shockproofing Technique
Input information read out of the CD at double speed is demodulated, stored in the memory,
and while sound-marking signal is supplied at normal speed from the memory to the D/A
converter, the residual data is accumulated in the memory.
If reaccess to the break point is accomplished before the memory becomes empty, apparent
playback sound is entirely kept free from breaking even when information pauses due to
vibration, etc. It was necessary to use the 16M bit memory for securing the accumulation time
of about 40 seconds.
9.2. Compression-shockproofing [Outline]
Fig. 4
is a block diagram showing the compression-shockproofing mechanism, the difference of
which from the conventional mechanism is as follows: Input information read out at double
speed undergoes data compression (16 bits -- 4 bits) by the encoder in the ADPCM (Adaptive
Difference PCM) and stored in the external memory; the stored memory information undergoes
data elongation (4 bits -- 16 bits) by the decoder in the ADPCM and supplied at normal speed to
the D/A converter.
The data compression technique has conduced to reduction of required memory capacity from
4M bits to 1M bit for securing the accumulation time equivalent to the conventional.
Fig. 4
Summary of Contents for SLSW850 - PORT. CD PLAYER
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