Printhead Safeguards - Lexmark W820 Service Manual

4025-XXX
Laser Hazards
Lasers generate a very powerful beam of light that produces extreme heat at its focal
point. The laser beam that the Printhead generates is invisible. Although you cannot see
the laser beam, direct eye contact with the beam will cause serious eye injury.
CAUTION: Always follow the laser service safety rules and use good judgement when
working on the printer.

Printhead Safeguards

There are two safety interlocks built into the CRU cavity.
A molded tab located at the end of the EP Cartridge actuates Interlock SW1 which,
along with SW2 (the Left Cover Interlock), controls +24VDC out of the MCU PWB. When
the Left Cover is open or the EP Cartridge is removed, SW1 and SW2 cut +24VDC out of
the MCU PWB.
An electrical jack at the end of the EP Cartridge completes the +5VDC circuit for CRU
Interlock switches SW1 and SW2. When the EP Cartridge is removed, +5VDC to the
Laser Diode is cut.
CAUTION: Never run the printer with the covers open or removed, the Main Interlock
Switch actuated, and/or the CRU Interlock Switches bypassed. Direct eye exposure to the
laser beam may cause serious eye injury.
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General Information