Checking Switch S7; Mirror Charged/Released - Minolta XD-11 Repair Manual

tw o shoulder screws. Fig. 59.
That's as far as you'll have to go in
disassembly to clean the brushes and the
resistor board. However, replacing the
resistor board requires a little more work.
First unsolder the seven connections join­
ing the resistor-board flex strip to the
main flex circuit. Fig. 54. A new resistor
board comes w ith the strip of flex circuit.·
Now remove the tw o screws, Fig. 59,
and lift out the resistor board. Notice that
you can shift the position of the resistor
board before tightening the screws. The
shifting adjustment allows you to precise­
ly align the minimum-aperture resistance
paths, Fig. 59, with the brush.
W hen you install the new resistor
board, be very careful to avoid over-
tightening the screw w ith the washer,
Fig. 59. Overtightening the screw can
break the connectors w ithin the flex-
circuit strip. You'll then have the same
problem — no MD common voltage.
Then, after you reassemble
diaphragm-metering ring and the lens-
mounting ring, adjust the position of the
resistor board. W ith no lens, the brush
R E S I S T O R - B O A R D S C R E W S
Figure 59
Figure 61
should center on the first resistance path.
Fig. 59. You might also check the adjust­
ment w ith the f/1 6 MD lens installed. A t
the f/1 6 setting, the brush should center
on the second resistance path.

CHECKING SWITCH S7

As mentioned earlier, the LED display
turns off when you release the shutter.
When M1 repels its armature, switch S7
opens. Fig. 52. Opening S7 disconnects IC2
from ground. So, if S7 fails to make good
contact, none of the LEDs will turn on.
W ith th e fro n t-p la te /m irro r-c a g e
assembly removed, you have a good view
of S7, Fig. 60. Fig. 60 shows the mirror
cage in the charged position. The M1 ar­
mature now sits in contact w ith the core
of the combination magnet. Notice that
the pin on the armature comes against
the blade of S7. The S7 blade then con­
nects to ground through the armature.
S7 remains connected to ground until
the
the M1 armature moves away from the
core. In Fig. 61, we're holding open the
shutter on bulb. Also, we've pushed the
M1 armature away from the core. As you
can see, the pin on the armature has
moved away from the S7 blade.
After the exposure, the cam ridge on
the mirror-tensioning lever, Fig. 62, once
again drives the M1 armature against the
core of the combination magnet. Cocking
the mirror cage for the next exposure
moves the cam ridge away from the M1
armature. Fig. 60. But, because of the
permanent magnet in the core of M1, the
armature remains in place.
You may have to remove the front-
plate/mirror-cage assembly to repair S7.
However, you can check S7 by just
removing the bottom plate. The white
wire connected to the S7 blade, Fig. 62,
goes to the lower circuit board.
Suppose, then, that none of the LEDs
will turn on. Try checking the continuity
between the w hite wire and ground. You
should measure direct continuity until you
release the shutter on an electronically
controlled speed. If you don't measure
direct continuity, S7 isn't making good
contact w ith the M1 armature.
Figure 60 M irror charged
Figure 62 M irror released
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