Thermal Head Protection - Ricoh C217 Service Manual

The time depends on the thermal head temperature which is detected by the
thermistor on the thermal head. If the temperature is higher, the time (t) will
be shorter.
ENR
Pulse
Length
The time(t) is determined when the Master Making key is pressed, and it is
kept until the master making is finished.

8.3.2 Thermal Head Protection

The thermistor on the thermal head and a thermal guard (a thermostat) on
the PSU are used for thermal head protection. This prevents the thermal
head and power supply unit from overheating when continuously processing
a solid image. The CPU detects the abnormal condition when the Master
Making key is pressed, and lights the SC code on the operation panel as
follows:
Detecting Component
Thermistor
Thermistor
Thermal Guard
C217
Long
Short
High
Conditions
Over 54°C
Under – 20°C (Thermistor open)
Over 85°C
2-50
Low
SC Code
E – 04
E – 09
E – 08
SM