80
Advanced
™
Osmometer Model 3250 User’s Guide
Stir/freeze amplitude adjustment
The stir and freeze vibration amplitudes are affected by the probe, stir/
freeze wire and mandrel positions. If the one-second freeze pulse is not
strong enough to freeze samples reliably, visually check the freeze and
stir vibration amplitudes as follows:
1. Make sure the Supervisor/Operator keyswitch is in the Supervisor
position while using the TEST and SETUP menus (see Figure 5).
2. Press the TEST key. The display will change to Select Test Item.
3. At Select Test Item, press the START key. The display will change to
Test Menu #: 0.
4. At Select Menu #: 0, press the 3 key; then press ENTER. The
display will change to Stir/Freeze Test.
5. At Stir/Freeze Test, press the START key. The display will change to
[stir] [freeze].
6. At [stir] [freeze], a freeze pulse will occur each time the > key
is pressed. Watch the tip of the stir/freeze wire and press >. If
properly adjusted, as recommended in Chapter 2, 14. Set "Buzz"
Amplitude, the stir/freeze wire should produce a loud "buzz,"
vibrate principally fore and aft, and never strike the probe.
Look from the side of the instrument as you press > again; the
freeze-pulse vibration blur at the very tip of the stir/freeze wire
should span at least ½" or 13 mm for one second, then cease.
If the freeze vibration is not enough, first remove the head cover by
removing the top screws and pulling straight up and make sure that
there are absolutely no metal chips between the clapper and the
coil armature. Even a single iron chip will greatly reduce the freeze
amplitude and must be carefully wiped out of the magnetic gap.
Then recheck the stir/freeze amplitude.
If the freeze vibration is still not enough, use either or both of the
following adjustments:
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