Theory Of Operation - Sony CDJ-500 Service Manual

P-CAV Drive
By using latest P-CAV (partical CAV) technology, the CDM-56 re-
alizes data transferring with variable transfer rate, from 12* (in-
ner track) to 24X (outer track).
Achieving 20X (3000kBytes/s) average data transfer rate, the CDM-
56 shows excellent performance.
*In the case of scanning velocity 1.3m/s and 60 min. disk reading.
FUNCTION OF PARTICAL CAV
CDM-56 (Drive unit) features Partical CAV capability for Maxi-
mum Speed, taking advantage of Wide Capture Range capability of
PLL (Phase Locked Loop) in its fastest speed mode.
Refer to the illustration on the left-hand side;
Spindle Motor rotates constantly at approximately 6,000 rpm, equal
to the rotational speed of 12X CLV on the innermost track, in the
area between the innermost track and the point of approximately 39
minuites (CAV area).
In the disc area outside the fore said 39 minutes, the spindle motor
follows the spindle speed curve of 24X CLV (CLV area).
Spindle Rotational Speed
Spindle Rotational Speed
12X-24X CAV area
6000
5000
0
Adress on the disc (min)
Data Transfer Rate
Data Transfer Rate (x 150kB/s)
24X
12X
0
Adress on the disc (min)
52
SECTION 6

THEORY OF OPERATION

24X CLV area
39 60
Average 20X
39 60
Disc In Balalaned Disc cancellation function
1 VCAN (Vibration Cancel) motor adopted by SPINDLE
CDM-56 has new type of spindle motor that cancels imbalance of a
disc automatically. Thanks to the new spindle motor, self -vibration
of the drive is reduced when the drive reads the imbalance disc.
2 Shock sensor adopted
CDM-56 has a feature that can detect excess vibration caused by
imbalance disc. Thanks to this feature, CDM-56 (CDM-57) auto-
matically reduce it's spindle speed to 8X-20X CAV mode when
such imbalance disc is inserted. It contributes to less vibration, less
audible noise, better readability and provides comfortable operat-
ing condition to end user.
Capable of Reading CD-RW disc
CDM-56 has the capability of reading CD-RW disc. CDM-56 can
automatically adjust RF amp gain and error amp gain to the proper
value for CD-RW disc, when CD-RW disc is inserted. But CDM-
56 can read CD-RW disc only at 4X speed.
Fast Access Time
Random access time is 90 ms* at P-CAV mode, which reduces vi-
bration of spindle rotational speed so that the access time improved.
Power Saving Mode
CDM-56 has a power saving mode. If any command which requires
disc access (such as READ or SEEK command) is not issued to the
drive for more than the inactivity time, which can be set by mode
select command, the drive goes into "standby mode" automatically.
Any command that requires disc access can resume the drive from
"standby mode".