Advanced Instruments 3900, Service Manual

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34
The Advanced ® Model 3900 Service Manual
Symptom Check Suggested Action
“ Sample Pre-freeze ” 1. Were the sample probe and tube
clean? Are the probe wipers dirty?
2. Is the probe configuration correct?
3. Check the stir/freeze wire
alignment and adjustment.
4. Is the sample frozen?
5. Does the clapper and/or the stir
wire coil show excessive wear?
1. Replace the probe wipers and test
another aliquot of that sample in a
clean sample tube. Check/correct
the probe bin numbers.
2. Correct the stir/freeze wire
alignment and adjustment, as
necessary.
3. Try to minimize the effects of
materials that tend to cause
premature crystallization.
4. False prefreeze errors may be
reported if the instrument cannot
maintain a cooling sample rate of
greater than 20 mOsm per 7
seconds.
5. Contact Advanced Instruments
for Hot-Line
®
Technical Service,
and possible replacement of the
yoke, clapper, and coil by a
qualified service technician.
“ Sample Probe Failure ”
Switch the instrument off, then on.
Check the sample probe by running
the A/D Test.
If the error message does not persist
and other messages are not
displayed, ignore this message.
Replace the sample probe.
“ Sample Probe Open? ”
Switch the instrument off, then on.
Check the sample probe by running
the A/D Test.
If the error message does not persist
and other messages are not
displayed, ignore this message.
Replace the sample probe.
“ Sample Tube Error ”
Check for a sample tube in the wrong
place, possibly in the operating head
or freezing chamber.
Review procedure and retry the test.
Remove the misplaced tube, check
the probe and stir-freeze wire
alignment, and retry the test.
If the error message persists,
contact Advanced Instruments
for Hot-Line
®
Technical Service.
“ Serial Loop Failed ” 1. Is serial loop-back connector
attached?
2. Did you wire loop-back connector
correctly?
3. Try lower baud rate.
1. Attach connector.
2. See User Guide, Chapter 5.
3. Change baud rate.