8.3.2Overheat Protection
The overheat protection circuit on the main board turns off the fusing lamp if the
temperature goes too high.
The input from TH1 (Hot Roller Thermistor) goes to pin 3 of IC17 as well as to the
CPU. As the temperature of TH1 increases, its resistance decreases and
therefore the voltage at pin 3 of IC17 increases. If this voltage becomes greater
than the voltage at pin 2, the output at pin 1 becomes HIGH. Q1 then turns off
and cuts the +24 volt supply to ac drive board. The fusing lamp then turns off.
The overheat protection circuit becomes effective at about 215°C.
TF1 provides overheat protection in case a short bypasses the control and drive
circuits. This fuse will open if it reaches approximately 192°C.
SM 2-30 A163
To Next Page
Loading...
Need help?
General