Brother FAX-8650P, Service Manual

Page: 27 / 196

III
- 10
2.3 Sensors and Actuators
This equipment has ten sensors: seven photosensors, two thermisters and a mechanical switch as
described below.
Sensor name Type Located on
Document front sensor Photosensor Control panel PCB ASSY
(Document sensor PCB)
Document rear sensor Photosensor Control panel PCB ASSY
(Document sensor PCB)
Top cover sensor Photosensor Main PCB
Sheet feeder cover sensor Photosensor Main PCB
Registration sensor Photosensor Main PCB
Paper ejection sensor Photosensor High-voltage power supply
PCB
Toner sensor Photosensor Toner sensor PCB
Toner thermister Thermister Toner sensor PCB
Heater thermister Thermister Heat-fixing unit
Hook switch* Mechanical switch 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.