Panasonic UF-890 Service Manual page 225

thermostat opens, removing power from the Fuser Lamp. When the
Thermostat opens, it must be replaced.
Paper Exit Sensor (610)
This sensor detects the presence of printed paper at the exit. If no paper passes, or if paper is over the
sensor too long, a "RECORDING PAPER JAM" message is displayed. When paper passes over the
sensor, the output is Low (Low Active).
Thermal Fuse (433)
It is placed in series with the Thermostat on the power line of the Fuser Lamp and performs the tertiary
overheating prevention (in case the Thermostat fails) by opening when the surrounding temperature
reaches approximately 216°C (420.8°F).
Drive Assembly and Toner Cartridge
The Drive Assembly, consisting of the Printer Motor (650) and the drive mechanisms, is activated by
coupling and gear arrangements.The Toner Sensor (639), a magnetic sensor, detects the remaining
quantity of toner in the Toner Cartridge.When the "TONER" lamp starts to blink, there is still enough toner
left in the cartridge to print 100 pages (based on ITU-T Image No.1). When toner has run out the display
will show: "OUT OF TONER & INFO CODE 041" and the machine is disabled from printing any
copies.The Toner Cartridge consists of OPC Drum, Bias Charge Roller, Development Roller,
Developing Blade, Cleaning Blade, Mixing Blades and Toner Waste Box.The OPC Drum is an aluminum
cylinder coated with an OPC (Organic Photo Conductor) sensitive material.This surface is photoelectric
(retains the charge in the dark and releases the charge in the light). The potential differences on the
surface (a static latent image) form a printed image.The Bias Charge Roller provides a uniform charge
on the OPC Drum surface.The Development Roller supplies toner to the drum by rotating over the
magnet.The Developing Blade evens the toner on the Development Roller surface and also charges
the toner by friction.The Cleaning Blade cleans by scraping the remaining toner off the OPC Drum
surface after transfer.
6.1.4 Covers and Enclosures
The Paper Guide Cover (110) contains Paper Guides (111), (112), which adjust to the paper width to
properly feed the original documents.The Front Cover (105) has a Speaker (133) mounted inside.The
Rear Cover (108) shields the circuit boards. The Printer Cover (122) contains the Document Sub Tray
(124), used to support legal size documents. The Left Side Cover (107) shields the Fuser Unit.
6.1.5 Control Panel
The Control Panel consists of the Panel PC Boards (214) and LCD Unit (215), which displays the various
status messages, and a membrane-type panel.
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