Canon A-1 Repair Manual page 140

3.4 eSC/ INTERFACE IC . (SN28722)
74
This IC provides the clock pulse an d system trigger for
the entire system. rt also provide s the interface between
the computer and the operational e lements (magnets).
1. MG2 (lP)
zv
...
.. . . ....
....
. . . .
....
.... ....
....
5~
Fig . 3-41
(Tr i gger: SNGl negative
going)
MG2 is activated by .the
combination signals,
SMGl and SMG3. Both
SMGl and SMG3 go low
together. 12 mS later
SMG3 goes hiqh for 5 MS.
This release MG2.
(It also electrically
releases SMG3 but it is
still latched mechanical-
ly .
When viewi ng the MG2 waveform, the C47 charging curve
is notica ble.
2. MG3 (2P)
This is the operation signal for the 2nd curtain
magnet (MG3) . As ment i oned above, MG3 is turned off
once but it does not re
l ease because
it
1s held
mechanically .
Fig. 3-42 shows the release curves for the first (false)
release and the actual release superimposed since they
have the same timing from the trigger. (See also
section 3.14.18)