Gestetner A193 Service Manual page 452

IMAGE FUSING
10.4 FUSING TEMPERATURE CONTROL AND OVERHEAT
PROTECTION
[B]
[A]
A224D504.wmf
The fusing control type can be either phase control or on-off control,
depending on an SP mode setting.
The fusing edge thermistor [A] has been added. It measures the temperature
at the end of the hot roller. This is because of the higher copy speed and
more power supplied to the fusing lamp. So, when making a multi-copy run
with A4 size paper, the temperature at the ends of the hot roller is higher than
at the middle.
Usually, the fusing temperature is controlled by using the fusing thermistor [B]
(at the middle). However, if the temperature at the end of the hot roller
becomes greater than 230° C, the fusing lamp will turn off until the
temperature at the middle of the hot roller has fallen by 5°C.
A224 13-18 SM