HP Color LaserJet 8500 Service Manual - Page 201

EPH controller board The external paper-handling (EPH) controller board controls the communication from the printer to the input and output devices. The EPH controller board PCA is integrated onto the printer formatter PCA. Duplexer The duplexer is installed below the fusing assembly. The back side of the paper is printed first. Then the paper is turned over and fed back through the paper path to print on the front side. The duplexer supports variable engine input speeds. 2,000-sheet input unit The 2,000-sheet input unit is a multi-speed high-capacity device that feeds paper to the printer. The 2,000-sheet input unit also automatically senses the paper size. Power supply The 2,000-sheet input unit has an internal power supply that is activated when the printer power switch is turned on. The EPH controller board on the printer sends a power-on signal to the power supply on the 2,000-sheet input unit. When the signal is high, the power supply provides both +24 V and +5 V to the paper deck driver. The +24V drives the motors, clutches, and solenoids for the lifter, feed, and pick-up systems. The +5 V drives the sensors and PCA electronics. EN EPH controller board 199