Advanced Instruments 4250, Руководство пользователя

Страница: 81 / 121

59
Troubleshooting & Service
22. If the current sample bin number setting is not the same as that just
determined, enter the correct bin number by means of the numeric
keypad; then press the ENTER soft key. The display will change to
“ Set Sample Bin # ” ; then press the STOP soft key to return to
“ Cryoscope Ready ” . If the current sample probe bin setting is the
same as that just determined, simply press the STOP soft key twice
to return to “ Cryoscope Ready ” .
23. Press the CALIB soft key and calibrate the instrument as recom-
mended in Chapter 4. Recalibration is required each time the sam-
ple probe is replaced.
Mandrel, probe and stir/freeze wire alignment
Probe and stir/freeze wire alignment using the alignment tool
(see Figure 9):
Proper alignment and adjustment of the mandrel, probe and stir/freeze
wire are of utmost importance to assure accuracy, precision and proper
operation of the instrument.
NOTE After making any probe and/or stir/freeze wire adjustments, the
instrument calibration must be checked and adjusted as neces-
sary.
To facilitate positioning of the probe and stir/freeze wire, a probe align-
ment tool is included with the instrument and with each replacement
sample probe. Alternatively, the probe and stir/freeze wire can be
aligned using a sample tube containing 2-mL of water. Both procedures
follow.
1. Slide the tool squarely up onto the mandrel,
round end first , with the
stir/freeze wire located as shown in Figure 9. Note that with
cryoscopes the tool must be rotated 90° from its position with
osmometers.
2. If aligning a metal probe, bend the metal probe stem gently by hand,
as necessary, to align the probe along the RAISED V CENTERLINE
of the probe alignment tool.