Advanced Instruments 3D3 - Power On Diagnostics; A;D Tests

The Advanced
®
3D3/4D3 Service Manual
Turn on the instrument At “Press START to
Continue”, press START. The instrument
performs a check of the cooling assembly and
the probes. If a Block Probe Failure, Sample
Probe Failure or Cooling System Error mes-
sage displays, use the A/D tests to perform
further testing.
A/D Tests
Note: You must set the correct sample and
block bin numbers before performing
A/D tests.
1. Turn on the instrument. If there is a
Supervisor/Operator keyswitch, turn it to
the Supervisor position (if required).
2. Press TEST.
3. Press < or > to select “A/D Tests”. Place
a sample tube containing either isopropyl
alcohol or 2000 mOsm calibration stan-
dard for a 3D3/4D3 into the freezing
chamber, and press START.
4. The display will change to:
off Blk NNNN.NN ohm
readout
(resistance or temperature)
channel setting
(sample or block)
target temperature
(off, +1 or -8)
5. Set the target temperature from +1°C to
-8°C by pressing < sequentially.
Note: For Intel processors, the head will not
lower until a target temperature is set.
The head will rise when the target tem-
perature is set to off.
6. Press > sequentially to read:
Block probe resistance in ohms,
Sample probe resistance in ohms,
Block probe in degrees Celsius,
Sample probe in degrees Celsius, or
Cooling block duty cycle (a % value).
Block probe resistance on instruments with
the Hitachi processor should be 4,990 ohms
when the target temperature is off and the
probe is warm. On instruments with the Intel
processor, the resistance will indicate current
temperature. The probe begins to cool after
the target temperature is set, and the resist-
ance increases until it reaches the target tem-
perature.
Sample probe resistance on instruments with
the Hitachi processor should be 4,990 ohms
when the target temperature is off and the
probe is warm. On instruments with the Intel
processor, the resistance will indicate current
temperature. The probe begins to cool after
the target temperature is set, and the resist-
ance increases until it reaches the target tem-
perature. Due to thermal mass considerations
between the positions of the block and sample
probes, the sample probe may be ± 0.5ºC of
the block probe reading.
Duty cycle displays the percentage of time
that the thermoelectrics power is on. When
the thermoelectrics begin to cool, the duty
cycle is usually at 100%. As the instrument
stabilizes, the duty cycle decreases to around
60%.
Increased ambient operating temperatures do
not affect the sample probe reading, but will
increase the observed duty cycle, up to 85%
at the maximum temperature of 35ºC.
Variations in ambient non-condensing relative
humidity have no effect on the sample probe
reading or duty cycle.
48
Power On Diagnostics