Canon A-1 Repair Manual page 134

68
10. 0 BUS (lOP)
T · B. 0
IH SI' ( M )
F
Zr
..
!
:..;. ' ~
11 '
I
t-
..
..
Iv
Once every 500 roS the CPU send three words of informa-
tion to the Decoder Driver IC thru the 0 BUS, or output
busllne . Only the TV and AV wor ds can be checked with
the Bus Checker. The Bus CheckEr trigger 1s used.
T ·R. 1
T ·
B. Z T· B.
3
T· B. • T ·
B. 5 T · B. 6
T ·
B. 7
DISP ( 2 )
DISP(3)
DlSP (')
DlSP (5 )
DlSP ( 6 ) DISP(7)
DUMP
TV (!i) TV ( 1 ) TV ( 2)
TV ( 4 )
TV ( H) TV ( 16 )
BEE
AV (Ji) AV ( I)
AV (2) AV ( 4) AV (8)
BULB
Fig. 3-28
>51
: 1
~
. . . .
:'10"
"
~ .
•
..
. ...
...
Fig. 3-29
!,uS
~J L
~~
I."
.. ..
.. .
.
1.4-1.6V
o-O.IV
(Tool and Trigger:
Bus Checker)
(Camera: TV, 1/1000)
The visable 0 Bus output
1s binary code of the TV
and AV signals. (Fig. 3-
28)
Figure 3-29 shows the
oscilloscope waveform of
the TV signal (first word)
and AV signal (second
word) .
Fig . 3-i9 Word 1 Binary
Code: 01011001
TV Signal Code (T.B 2 - 7)
01 1 001
converts to
Octal Code:
From the TV Code Table:
230
z
1/1000 sec. shutter
speed
The second word in the code di s played in Fig. 3-29
is the AV code. As shown 1n Fig . 3-28, T.B 0 and
T.B 1
are not a part of
the AV c ode . When converting
to Octal code they sho uld be c onsidered as "00"
(This is true of the TV code aiso).