LI-610 Dew Point Generator Temperature Setpoint Cannot be Adjusted

Turning the Temperature Adjustment knobs on the front panel of the LI-610 Dew Point Generator sometimes may not change the Temperature shown on the display. Even if the switch is toggled to the correct position at SET TEMP, twisting the knobs may have no effect on changing the temperature setting on the display.

Some users of the LI-610 Dew Point Generator utilize a computer, software, or other external devices to automatically control the temperature functions and set points of the LI-610.The potentiometer knobs are thus not used as a manual control. The user can connect a BNC cable to the Command Input on the front panel of the Dew Point Generator (see the Manual, page 3-4 for more details on this) to control the temperature externally.

There is a jumper inside the LI-610 that is sometimes removed for this, although it is not necessary to remove this jumper for the Command Input to work. If the jumper is removed, it disables the control knobs that also allow temperature setting. This may be a precaution that users perform to prevent changing the temperature setting if the knobs are accidentally turned. Again, this is not necessary for the Command Input to work. An incoming signal will override the signals from the temperature control knobs. This missing jumper is something to check when troubleshooting the LI-610 Dew Point Generator if the temperature set point cannot be adjusted. Please see the image below for the location of this jumper. Make sure the problematic Dew Point Generator also has this jumper positioned correctly. The LI-610's case needs to be opened to inspect this.

More commonly, this problem has to do with damage from an electrical surge. Power and electrical surges can cause damage to the some of the internal components that are used to adjust the temperature settings. To repair this, the unit must be returned to LI-COR.