Fluke 6050H User Manual page 64

6050H Calibration Bath
User's Guide
62
Problem Causes and Solutions
The display flashes Low battery. A problem could exist with the memory back-up battery. If the bat-
"CUToUT" alternately tery voltage is insufficient to maintain the memory, data may become scrambled
with an incorrect process causing problems. A nearby large static discharge may also affect data in mem-
temperature ory. Access the battery by removing the L-shaped panel covering the display
electronics.
Corrupt controller memory. If the problem reoccurs after the battery is replaced,
initialize the memory by performing a Factory Reset Sequence (described in a
previous solution).
The controller displays Defective control probe. The bath control probe may be disconnected, burned
the wrong temperature out, or shorted. Check first that the probe is connected properly to the socket in
and the bath continually the rear of the bath labeled "PROBE".
heats or cools regardless
The probe may be checked with an ohmmeter to see if it is open or shorted.
of the set-point value
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. The resistance should read from 100 to 300 ohms be-
tween pins 1 and 4 depending on its current temperature.
Corrupt controller memory. Initialize the memory by performing a Factory Reset
Sequence (described in a previous solution).
The controller controls or If the controller appears to operate normally except that the bath's temperature
attempts to control at an does not agree with the temperature measured by the user's reference ther-
inaccurate temperature mometer to within the specified accuracy, consider the following:
Erroneous parameters. Check that the calibration parameters are all correct ac-
cording to the Report of Calibration. If not, reprogram the constants. If the con-
troller does not keep the correct parameters, the memory backup battery may
be weak causing errors in data. See "Low Battery" in a previous solution.
Poor uniformity. There may be an actual difference between the bath's control
probe and the reference thermometer due to excess gradients in the bath.
Check that the bath has an adequate amount of fluid in the tank and that the
stirrer is operating properly. Also check that the reference thermometer and
control probe are both fully inserted into the bath to minimize temperature gradi-
ent errors.
Defective control probe. Check that the control probe has not been struck, bent,
or damaged. Refer to the previous solution for how to check the probe's
resistance.
The controller shows that If the bath does not achieve the expected degree of temperature stability when
it is controlling at the measured using a thermometer, consider the following:
proper temperature, but
Wrong proportional band setting. If the proportional band is set too narrow, the
the bath temperature is
bath will oscillate causing poor stability. In this case, increase the width of the
unstable
proportional band.
If the proportional band setting is too wide, the long-term stability of the bath is
affected. In this case decrease the width of the band. (Refer to Section 9.7.)
Bath salt is too thick. Make sure that the bath salt used is less than 50 centi-
stokes (10 is ideal) at the temperature at which the bath is controlling. Check
the salt manufacturer's specifications.
Defective control probe. Check that the control probe has not been struck, bent,
or damaged. Refer to the previous solution for how to check the probe's
resistance.
The controller alternately Wrong proportional band setting. If the proportional band is set too narrow, the
heats for a while then bath will oscillate between too much heating and too much cooling causing in-
cools stability. Increase the width of the proportional band until the temperature stabi-
lizes. (Refer to Section 9.7.)