Service Manual

Because the CdS and the BALANCING resistor (VR-1) are series connected, the voltage
from the power supply is affected by the degree of resistance offered by both and the
voltage equivalent to the VR-1 is applied to (T5)-(T1).
Both the OVER and UNDER indicator lamps fail to turn on (indicating correct exposure)
when the voltage range at (T5)-(T1) is between 0.6 V and 1.0 V. The OVER indicator
lamp turns on when the voltage rises above this level and the UNDER indicator lamp
alights when it falls short of this range. Consequently, the procedure for setting the
correct exposure (indicated by the OVER/UNDER lamps failing to turn on) consists of
adjusting the VR-1 to a setting where a voltage supply of 0.6 V to 1.0 V will be
maintained at (T5)-(T1) as against the CdS resistance value.
1.2 Simultaneously with the setting of the resistance value of the VR-1 through
exposure readout, the shutter speed resistor (VR-2) which is set coaxially is adjusted
accordingly.
a. The trigger switch (SW-5) is adjusted to "ON" position when the shutter is
charged.
b. When the shutter release button is depressed, the power switch (SW-2) on
the shutter side is turned on, setting the power supply to the circuit. At this stage,
however, the Tr6 and Tr7 are at "ON" position because Tr5 is turned off. Consequently,
the magnet functions to hold the rear sector of the shutter.
c. At the next stage, the trigger switch is turned off and the electric current
controlled by the setting of the shutter speed resistor begins to flow and the charging of
the condensor C1 starts. Immediately after the trigger switch is turned off, the front
shutter sector is activated mechanically and starts its function.
d. The electric potential of the condenser C1 rises gradually and, when it
reaches a given (approx. 2.4 V), the Tr5 turns on and, simultaneously with this, the Tr6
and Tr7 are switched off. This cuts off the supply of electric power to the magnet which
then loses its force of attraction, causing the rear sector to commence operation.
e. As soon as the rear sector completes its run over the entire picture area,
the SW-2 is turned off, thus cutting off the supply of the electric power to the shutter
circuit and completing the shutter operation.
Principle of variation of the shutter speeds
The shutter speed is decided through setting of the shutter speed resistor
(VR-2).
If, for instance, only a very low resistance is offered by the VR-2, a large flow of electric
current is supplied to the condenser C1, necessitating only a very short period of time to
charge it to full capacity. In other words, the terminal voltage of the C1 rises to a given
value within a very short period of time, causing the rear sector to start to function with
hardly any time delay and thus providing fast exposure. If, on the other hand, a high
resistance is offered, a restricted flow of electric current is supplied, requiring a
considerable period of time before the terminal voltage of the C1 can reach level and thus
providing long exposure.