Minolta XG7 - Troubleshooting Chart Usage Instructions

20
Auto Mode:
It
consists
of
CdS
and
two
resistors.
Even
if
the
resistance
of
CdS
circuit
changes
(the
brightness
of
the
scene
changes),
the
voltage
applied
to
the
circuit
is
kept
constant
by
the
operational
amplifier,
thus
making
the
current
{i
,)
proportional
to
the
brightness.
The
current
(i,),
SV
and
AV
information
from
the
resistors
are
treated
by
the
operational
as
voltage
corresponding
to
the
exposure
time.
The
voltage
is
applied
to
the
memory
circuit
and
indication
circuit
through
the level shift circuit (including VR:. VR;).
Manual Mode:
When
the
mode
is
shifted
to
Manual,
CdS
circuit
is
switched
to
standard
resistor
(VR,)
to
make
current
(i)
constant.
Also,
the
brush
of
SV
resistor
is
switched
to
that
of
TV
resistor
(resistor
is
used).
Therefore,
the
output
to
the
memory
circuit
varies
in
accordance
with
the
position
of
the
brush
for
TV
resistor.
To memory circuit
Operational
amplifier VR;
sv M
= - VR;
an A.V
To indication circuit
. Indication circuit
The indication circuit is a combination of comparators, which compares the output of
calculation circuit and the standard voltage created in the indication circuit. When the
values are close to each other, the corresponding LED is lighted. When the output of
calculation circuit is between standard voltages intermediate range), two LED's are
lighted.
The output of calculation circuit is compared with the standard voltage by comparators
in the indication circuit (IC 2). When the values are close to each other, the corres-
ponding LED is lighted. When the value is in an intermediate range, the outputs are
given from two comparators to two LED's to turn them on at the same time.
When the over-range warning LED is lighted the over-range lock signal is given to the
release circuit to lock the release. Also, when the signal for charge completion is
emitted from exclusive strobo (8668). the comparator is turned off (LED OFF), then
LED “60” is turned on end off by the signal.
Va < Vb € Ve € Vd < Ve
Standard voltage
1
ff
I
‘Tr
le
T
Calculation
eireuit
out put
Com
parator| | parator
Com —
parator | |parator | | parator;
Strobo signal input terminal
a — Indication LED
a 1/60
Srercange wom [Retene even]