During the run, the temperature on the A200 controller drops 10°C or more and then recovers. The heat light remains ON when the temperature drops. Why does this happen?

The instrument is experiencing a high-temperature fault. If your controller is set to 100°C, there are two possible reasons for this fault.

(1) The agitation is not working properly during an assay.  

To check the agitation during an assay, remove the back panel of the instrument and do the following:

Check that the motor fan is spinning (refer to the A200 internal components document below). If the motor is not spinning, turn off and unplug the instrument. Then, loosen the brass packing nut 1/2 turn and check the wiring connections to the motor. Plug the instrument back in and press the Agitate button. If the motor starts to turn, reset the packing nut. Refer to Service Procedure Packing and Agitator Replacement (DES002) for instructions. If the motor does not turn after loosening the packing nut and the wiring connections are good, replace the motor. Refer to A200 Service Procedure Motor Installation and Alignment (FS007) for instructions.

Check that the agitator shaft is spinning. Refer to the A200 internal components document below, Look between the maintenance alert collector and the helical coupler. If the motor fan is spinning, but the agitator shaft is not spinning, then one or both set screws on the helical coupler need to be tightened. Turn off and unplug the instrument before tightening the set screws.

(2) The actual temperature has exceeded the ETS capacity and must be replaced.

To replace the ETS, remove the back panel of the instrument and locate a black object bolted to the upper left side of the vessel (refer to A200 internal components). NOTE: Attached to the bottom of the ETS is an orange wire and attached to the top is a cloth-covered wire. Disconnect the existing ETS and install a new one in its place.