Tally Dascom 7010, Maintenance Manual

Page: 43 / 255

2-2. Operation of Control Parts
2-27
(6) PF motor temperature sensor
The PF motor temperature sensor is used to detect the temperature of the PF Motor. This
sensor is a thermistor bonded to the PF Motor. Since the resistance of the thermistor changes
according to the temperature change, the voltage at pin 8 (MOTTMP) of U1 (CPU) changes
accordingly. The CPU senses the voltage at pin 8 to detect the PF motor temperature.
Printing operation when the PF motor temperature rises:
When the temperature of the PF motor rises to 95
°
C (203
°
F), printing speed is reduced to
avoid overheating. If it reaches 105
°
C (221
°
F), the PF motor stops after printing the current
label. In this case, the ERROR LED blinks and the LCD displays "Alarm PFMotor Hot" on the
operation panel.
When the temperature of the PF motor falls below 90
°
C (194
°
F), the LED stops blinking, the
LCD returns to the original display “On Line”, and printing resumes.
In addition to the PF motor temperature rise detection by the CPU, the circuitry composed of
U19A OP amp. detects the high temperature over 130
°
C (266
°
F) to protect the PF motor. If the
PF motor temperature exceeds 130
°
C (266
°
F), the output of U19A is reversed and TEMPOFF
signal goes “Low”. As a result, +24V supply to the PF motor driver circuit is shut off. (For a
detailed description, refer to 2-2-4 “
(1) PF motor driver (1) PF motor driver(1) PF motor driver”.)
When the PF motor temperature falls below 125
°
C (257
°
F), the output of U19A returns from
“Low” to “High” so that +24V supply to the PF motor driver circuit resumes.
90
°
C
(194 ° F)
95
°
C
(203
°
F)
Normal speed
(Stop)
Normal speed
Normal speed
105
°
C
(221
°
F)
Low speed
(Stops)
(Stop)
1
J5
M
PF Motor
2
PF Motor Temp. Sensor
(Thermistor)
VREF
R110
C78
U1 CPU
[Main PCB]
MOTTMP
ANI3
8
TMPOFF
(To PF Motor Driver)
VREF
U19A
uPC393GR-9LG
-
+
3
2
1
VREF
R112
R114
R113
R115
R111
R116