Brother International FAX-8650P Service Manual - Page 27

2.3 Sensors and Actuators This equipment has ten sensors: seven photosensors, two thermisters and a mechanical switch as described below. Sensor name Document front sensor Document rear sensor Top cover sensor Sheet feeder cover sensor Registration sensor Paper ejection sensor Toner sensor Toner thermister Heater thermister Hook switch* Type Photosensor Photosensor Photosensor Photosensor Photosensor Photosensor Photosensor Thermister Thermister Mechanical switch Located on Control panel PCB ASSY (Document sensor PCB) Control panel PCB ASSY (Document sensor PCB) Main PCB Main PCB Main PCB High-voltage power supply PCB Toner sensor PCB Toner sensor PCB Heat-fixing unit Hook switch PCB* *Not provided on the FAX-8650P. • Document front sensor which detects the presence of documents. • Document rear sensor which detects the leading and trailing edges of pages to tell the control circuitry when the leading edge of a new page has reached the starting position and when the scan for that page is over. • Top cover sensor which detects whether the top cover is closed. • Sheet feeder cover sensor which detects whether the sheet feeder cover is closed. • Registration sensor which detects the leading and trailing edges of paper, which allows the controller to determine the registration timing and check paper jam. • Paper ejection sensor which detects whether the recording paper goes out of the equipment. • Toner sensor which detects whether there is toner or a toner cartridge is loaded. • Toner thermister which detects the ambient temperature of the toner cartridge. • Heater thermister which detects the temperature of the heater roller of the fixing unit. • Hook switch* which detects whether the handset is placed on the handset mount. These photosensors are a photointerrupter consisting of a light-emitting diode and a light-sensitive transistor. Each of them has an actuator separately arranged as shown on the next page. III - 10