Fluke 7381 - Page 62

7381
User’s Guide
56
The controller does not maintain
controller parameters or
parameters are reset each time the
power to the unit is removed
Note
Before you perform the memory check, you must
record the controller calibration parameters
(found in the CAL menu) and any user-adjusted
parameters that you have changed (such as the
programmable set-points and proportional
band).
Memory Check
The easiest way to verify the ability of the battery to
maintain controller parameters, is to do a memory check.
1. Power off the Product.
2. Disconnect the instrument from ac power for
10 seconds.
3. Reconnect the ac power and power on the Product.
4. If the display shows
InIt and/or the cycle count
shows a low number, such as 0002, the battery is
spent and needs replacement. Contact Fluke
Calibration.
5. After the battery is replaced, you must reprogram the
calibration and user-adjustable parameters into the
controller.
The controller shows that the
output power is steady but the
process temperature is unstable
Possible causes are an improper proportional band
setting or the fluid under use.
• If the bath temperature does not achieve the
expected degree of stability when measured with a
thermometer, try to adjust the proportional band to a
narrower width as discussed in Proportional Band.
• Make sure the fluid has not deteriorated or is not too
thick.
The controller alternately heats for
a while then cools
The Bath is unstable and the duty cycle is not constant.
The proportional band being too narrow typically causes
this oscillation. Increase the width of the proportional
band until the temperature stabilizes as discussed in
Proportional Band.
Table 6. Troubleshooting (cont.)
Problem Causes and Solutions