Service Manual

4.2.5.2 The 'light turn-off' range is either excessive or too limited.
The factory standard calls for a 'light turn-off' range of 1/3 to 1-2/3 EV and, therefore, the
following adjustment must be made in case the range is determined to be excessive or too
limited. Because this range is adjusted on the basis of the function of the "OVER"
indicator lamp, the VR-1 must be properly regulated in case it is determined after
adjustment of the 'light turn-off range' that the 'light turn-off point' has shifted from the
normal position. (Refer to pertinent details given later.)
1. Excessively wide 'light turn-off range'.
This can be attributed to adjustment of the 'light turn-off range' adjustment resistor
(30K ohm VR) to a resistance reading below the normal level. To repair, turn the resistor
in a left motion with the aid of a screw-driver to a setting that provides higher resistance.
2. The 'light turn-off' position generally tends to shift toward a direction providing over-
exposure at all light levels.
This malfunction is caused when the resistance of the BALANCING resistor (VR-1)
declines below the standard level. To make adjustment, turn the offset resistor ring in a
right motion.
4.2.5.3 In case both the 'light turn-off range' and 'light turn-off
position' are determined to be not up to standard.
First of all, adjust the 'light turn-off' adjustment resistor (30K ohm) and set the 'light turn-
off range' to normal level. Then, adjust the BALANCING resistor ring (VR-1) and set
the 'light turn-off point' to the required position.
4.3 Shutter circuit
4.3.1 Shutter speed
4.3.1.1 Malfunction of the shutter power switch (SW-2)
In this case, the SW-2 fails to turn on. When using a DC voltage stabilzer, a flow of
electric current to the extent of about 30ma (at 5.5V) should be determined at the time the
shutter is released. Poor contact of the SW-2 is caused occasionally by accumulation of
dust or other foreign particles. To repair, therefore, wipe and clean the contact pieces
meticulously.
4.3.1.2 Disruption of the wiring of the electro-magnet.
Remove the black lead wire and undertake continuity test on the electro-magnet. The
resistance value should be approximately 270 ohms (with both electro-magnets).
4.3.1.3 Shortcircuiting of the shutter speed resistor (VR-2) circuit.
This can be attributed to either shortcircuiting of the shutter printed wiring panel or
shortcircuiting within the VR-2. In this case, remove the yellow or pink lead wire and
check the insulating resistance between the colored patterns. Also, undertake continuity
test of the VR-2.
The resistance of the VR-2 should be within the limit specified in Fig. 2.2.2.
4.3.1.4 Malfunction of the amplifier unit.
If everything is found to be in order after undertaking [the] thorough check outlined in
the preceeding three paragraphs, the cause can be pinpointed on malfunction of the
transistors, in which case the amplifier unit must be replaced.
4.3.2 Shutter remains open.