W820 (4025-xxx)

4025-XXXThe PSHV-R2 converts the +24VDC received from the I/O PWB into the bias voltagerequired by the Fuser.Safety Interlocks for the printer are made up of two separate switches that are wired inseries with the I/O PWB and one switch that is attached to the MCU PWB. When theFront Cover is open, the Front Cover Interlock Switch cuts +24VDC output from theMCU PWB.When the EP Cartridge is in place, Interlock Switch SW1 is closed. When the Left HandCover is closed, Interlock Switch SW2 is closed. With both switches closed, the circuit iscomplete and the I/O PWB sends +24VDC to the HVPS and other printer components. Ifeither SW1 is open (the EP Cartridge removed) or SW2 is open (the Left Hand Cover isopen) the I/O PWB cuts all +24VDC output from the I/O PWB.1-10 Service Manual