Fluke 7341 User Manual page 94

7341
Users Guide
The displayed process
temperature is in error and the
controller remains in the cooling
or the heating state at any set-
point value
The controller controls or
attempts to control at an
inaccurate temperature
13-4
• If the problem reoccurs, the battery should be replaced. Contact an
Authorized Service Center (see Authorized Service Centers in
Chapter 1) for assistance.
•
If initializing the memory does not remedy the problem, there may
be a failed electronic component. Contact an Authorized Service
Center (see Authorized Service Centers in Chapter 1) for
assistance.
•
The controller may need to be reset. Perform the following Factory
Reset Sequence.
Factory Reset Sequence. Hold the SET and EXIT buttons down at
the same time while powering up the instrument. The instrument
display shows '-init-', the model number, and the firmware version.
Each of the controller parameters and calibration constants must be
reprogrammed. The values can be found on the Report of Test that
was shipped with the instrument.
Possible causes may be either a faulty control probe or erroneous data
in memory.
•
The probe may be disconnected, burned out, or shorted. The probe
is located inside the stirrer motor cover.
•
Check that the probe is connected properly. The probe may be
checked with an ohmmeter to see if it is open or shorted. The probe
is a platinum 4-wire Din 43760 type. The resistance should read 0.2
to 2.0 ohms between pins 1 and 2 on the probe connector and 0.2
to 2.0 ohms between pins 3 and 4. It should read 100 to 300 ohms
between pins 1 and 4 depending on the temperature. If the probe
appears to be defective, contact an Authorized Service Center (see
Authorized Service Centers in Chapter 1) for assistance.
•
If the problem is not the probe, erroneous data in memory may be
the cause. Re-initialize the memory as discussed in the problem
'The display flashes "cutout" and an incorrect process temperature'.
If the problem remains, the cause may be a defective electronic
component, contact an Authorized Service Center (see Authorized
Service Centers in Chapter 1) for assistance.
The controller operates normally except when controlling at a specified
set-point. At this set-point, the temperature displayed does not agree
with the temperature measured by the user's reference thermometer to
within the specified accuracy. This problem may be caused by an actual
difference in temperature between the points where the control probe
and thermometer probe measure temperature, by erroneous bath
calibration parameters, or by a damaged control probe.
•
Check that the bath has an adequate amount of fluid in the tank and
that the stirrer is operating properly.
• Check that the thermometer probe and control probe are both fully
inserted into the bath to minimize temperature gradient errors.
•
Check that the calibration parameters are all correct according to
the Report of Test. If not, re-program the constants. The memory
backup battery may be weak causing errors in data as described in
the problem: 'The display flashes "cutout" and an incorrect process
temperature'.
•
Check that the control probe has not been struck, bent, or damaged.
If the cause of the problem remains unknown, contact an Authorized