Minolta XD-11, Руководство по ремонту

Страница: 34 / 56

the variable resistors on the side of the
mirror cage.
To check the A SA inclination, measure
the voltage between the lead of Rx1 and
the flex-circuit land that has the gray SV
wire, Fig. 71. You should measure 144mv
± 2 m v. Adjust the voltage by turning the
wiper of Rx1 — clockwise to decrease the
voltage, counterclockwise to increase the
voltage.
AUTO EXPOSURE ADJUSTMENT
Adjust Rx2, Fig. 71, to correct the auto
exposure in the A mode. Minolta recom­
mends testing the automatic shutter
speeds at f/5 .6 , A SA 100. Check the ex­
posure at EV 15, EV 11, and EV 9. Be sure
to shield the top of the camera from am­
bient light, especially at the EV 9 light
level.
CHECKING THE AUTO DIAPHRAGM
OPENINGS
There's no adjustment for the auto
diaphragm openings. However, you
should still check the accuracy. Checking
the auto diaphragm openings at the S
mode verifies proper operation as well as
the accuracy of the previous adjustments.
Set the mode selector to S. Then check
the diaphragm opening at ASA 100 and
EV 11. Remember, the diaphragm-setting
ring must be at the smallest aperture set­
ting. The follow ing chart shows the ac­
tual aperture and the exposure time you
should be getting at different shutter-
speed settings:
CHECKING THE LED READOUT
Now check the accuracy of the LED
readout. Check first to make sure that the
LEDs light properly all along the scale. If
the LEDs at either end of the scale don't
show up — or if the LEDs do n 't appear
uniform ly bright or centered throughout
the display — you may have to shift the
circuit board at the side of the mirror
cage, Fig. 48.
The LED display mounts to the circuit
board at the other side of the flex circuit,
Fig. 48. A fter loosening the tw o ground
screws, you can shift the positon of the
circuit board to align the LEDs w ith the
mirror-cage prisms. Make sure that each
LED in the display centers w ithin its hole
in the viewfinder mask.
You're then ready to verify the ac­
curacy of the readout. First check the ac­
curacy in the A mode, A S A 100, and EV
11. A t f/2 .8 , the "250" LED should turn
on. A t f/8 , the "3 0 " LED should turn on.
And at f/1 6 , the " 8 " LED should turn on.
Next check the accuracy in the S mode
at f/1 6 , EV 11. A t 1/15 second, the f/11
LED should turn on. The f/5 .6 LED
should turn on at 1/60 second. A t 1/500
second, the f/ 2 LED should turn on.
If the LED readout is not w ithin 1 EV,
recheck your previous adjustments. Use
variable resistors Rx5 and Rx6, Fig. 48,
only as a last resort. If necessary, you can
then use Rx5 to adjust the readout in the
S mode. Use Rx6 to adjust the readout in
the A mode.
ADJUSTING THE UNDERRANGE
LED INDICATION
The final "n o rm a l" adjustment sets the
turn-on point of the underrange LED. But
the adjustment takes some time — you
have to compare tw o voltage measure­
ments. First, set the mode switch to S,
the shutter speed to 1/250 second, and
the diaphragm to f/16.
W ith the film-speed dial set to ASA
100, expose the lens to a light level of EV
9. Now measure the voltage between the
common S11 path, Fig. 66, and ground.
Record your voltage reading.
Next, w itho u t changing anything, mea­
sure the voltage between pin 8 of IC1 and
ground. You can measure the pin 8
voltage at the gray-wire land pointed out
in Fig. 71. Compare this voltage reading
w ith your measurement at the S11 land.
Finally, turn the film-speed dial until the
voltage at the gray-wire land is 12 to 13mv
lower than the voltage at S 11. For exam­
ple, suppose that you measured 1.313V in
the first step. You must then set the
voltage at the gray-wire land to 1.3
-1.1301V. Move the film-speed brush
along the resistance band until you get
the proper voltage at the gray-wire con­
nection.
Now look through the finder — the
underexposure LED should just begin
lighting. Adjust Rx4, Fig. 71, so that the
underexposure LED just starts to glow
when the f/1 .4 LED turns on.
CHECKING THE DEDICATED-
FLASH OPERATION
Before closng up the camera, you
should check to make sure the circuit will
program the flash speed and indication
w ith a dedicated flash. The AX signal pin,
Fig. 71, receives the signal from the flash
unit. W ith the flash unit fully charged, the
signal at pin 1 of H-IC, Fig. 63, turns on
transistor T10.
Turning on T10 connects pin 11 of IC1
to ground. Consequently, the diaphragm
always closes to whatever f/s to p you've
selected. Also, transistor T9 turns on,
connecting one lead of the electromagnet
to ground. The shutter then stays open
for a length of time determined by the
flash unit. As soon as the flash unit turns
o ff T9, the shutter closes.
So, if you apply a positive signal to the
AX signal pin, you should be able to hold
open the shutter. The positive voltage
keeps transistor T9 turned on. Since tu rn ­
ing on T9 connects one lead of M3 to
ground, current continues to flo w
through the electromagnet.
Also, the positive signal should turn on
the overrange LED. In Fig. 63, you can
trace the signal from pin 1 of H-IC to IC2.
The signal at pin 5 of IC2 turns on the
overrange LED.
Connect a DC power supply between
ground (negative) and the AX signal pin.
Set the mode switch to M, and set the
speed selector to 1/1000 second. Before
turning on the power supply, check the
LED indication by depressing the release
button; you should get the available-light
indication.
Now set the power supply to 1.3V.
W hen you push the release button part
way, the overrange LED should turn on.
Next set the power supply to 1.6V and
release the shutter. The shutter should
stay open until you turn off the power
supply.
SHUTTER SETTING DIAPHRAGM OPENING EXPOSURE TIME
1/125 second f/4 3.91 - 15.6ms
1/60 second f/5 .6 7.81 - 31.3ms
1/30 second f/8 15.6 - 62.5ms
1/15 second f/11 3 1 .3 -125m s
If you're using an instrument that measures EV error, the exposure should be
w ithin ±0.8V at each shutter-speed setting. An out-of-tolerance reading normally
indicates an error in the previous adjustments.