Samsung MM-18 Service Manual page 18

mm18(10) 3/23/98 3:14 PM
5-1-5 Mirror Circuit
After RFI signal is amplified by mirror amp, mirror signal is held in peak and bottom circuit. The following of
100KHZ traverse is possible in peak hold circuit and the loss of track count due to defect is counted in bottom
hold circuit. Mirror output beyond 2KHz is. ÒLÓ at track on disc, ÒHÓ at interval between track on disc, ÒHÓ
when the defect beyond 1.4ms is detected.
The time constant for the mirror hold must be sufficiently large than of the traverse signal
5-1-6 EFM Comparator
The EFM comparator converts a RF signal into a binary signal
As the asymmertry due to variations in disc manufacturing can not be eilminated by thr AC coupling alone,
the reference voltage of EFM comparator is controlled utilizing the fact that the generation probability of 1,0
50% each in the binary EFM signals.
Samsung Electronics
Page 5-3
38K
17K
IRF 75
-
+
19K
40K
RFI 77
19K
2.5K
17K
Peak and
-
Bottom
Hold
+
96K
100K
20K
100K
85K
Special Circuit Descriptions
-
1.5K
1 MCP
+
-
39 MIRROR
+
EFM
1
ASY
39
5-3