Canon A-200 series Service Manual page 82

When both PSO and PS1 are LOW, an output from 20 terminal of U126 is sent to the FOO as
written data.
When PSO is LOW and PS1 is HIGH, this status is called as Late mode. In this mode an output
from 30 terminal of U126 is sent to the FOO. This data is delayed for one clock cycle (125 nano
seconds).
In Early mode - when PSO is HIGH and PS1 is LOW - an output from 10 terminal of U126 is
sent to the FOO. This data is advanced for 1 clock cycle.
The SYNC signal of the FOC permits read operation at HIGH level, and inhibits at LOW.
U126
8M
.....
" ,
ClK
WO 40 40
' - - ­
10
10
C1
FOC
2D
20
CO
Y~
To FDO
WRITE
r-- 30
30
C2
ClR
U72
SYNC
10
PS1
B
PSO
A
Figure 6-24
• Data Separation Circuit
The heart of this circuit is the VFO-IC, U104 (SE09420COB).
The VFO emits the Window signal to separate data bits and clock bits from the data read from
the FOO.
The FOC uses the data mode of the VFO at the MFM terminal.
When the output of the MFM terminal is LOW, it assigns FM mode and when HIGH, assigns
MFM mode.
Vee
CN15
U133
OATAt------./RD
WI NOt-------t WIND
VFO
FDC
U104
MFM/FM t-o-----fMFM
Figure 6-25
79