Citizen CL-E720DT Technical Manual page 49

Chapter 2 Operating Principles
2-2.
Operation of Control Parts
Abnormally high temperature detection:
To protect the cutter motor from being damaged, an abnormally high temperature detection
circuit is provided. If the temperature of the cutter motor exceeds a set temperature limit, the
LED on the operation panel blinks in red and the LCD displays "Error System Fail", and the
printer goes off-line. To recover from the error status, turn OFF the printer once and then turn it
ON.
A reference voltage, i.e., an allowable temperature limit, is applied to pin 5 of the comparator
(U8B), while the sensor output voltage (TMPCUT) from the cutter motor temperature sensor is
applied to pin 6.
If the temperature of the cutter motor becomes higher than the set temperature limit, the cutter
motor temperature sensor output voltage exceeds the reference voltage at pin 5, and pin 7 of
U8B goes to "Low" level. At this time, pin K1 (nTMPERR) is "Low" and the FPGA detects an
abnormally high temperature.
In this abnormal state, the printer stops +24V DC (VMT) supply to the cutter. Also it stops +24V
DC supply to the "SA Head" and "SA PF Motor".
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CL-E720DT