W820 (4025-xxx)

4025-XXX39. No Paper Sensor 2Monitors the paper level in Feeder 2. Functions identical to No Paper Sensor 1.40. Level 2 SensorMonitors whether or not Tray 2 is installed.41. Size Sensor 2Monitors the size of the paper that is loaded in Feeder 2.42. Take Away Roll Sensor 2Monitors the paper travel at the Take Away Roll 2.43. Lift Motor 2Raises the paper tray in Feeder 2.44. Left Cover Interlock 2Monitors the Left Cover Interlock Switch on Feeder 2.Control Functions of the Machine Control Unit (MCU)1. Input from sensorsSensors tell the MCU what is going on within the printer and what is happening tothe sheet of paper during a print cycle.Example:Printer sensors send their current status to the I/O PWB, which transfers the data onto the MCU PWB. The sensor status signals tell the MCU whether they are actuatedor not actuated (on or off, high or low). If measured with a voltmeter, some sensorsignals to the MCU would be +5VDC when on and 0VDC when off, while othersensors may be 0VDC when on and +5VDC when off. In some cases, signal namesmay indicate what reading you should get when the signal is on. For example, thesignal name PRINTHEAD MOTOR ON (L) 5VDC means when the Printhead Motorsignal is on, the reading goes low (0VDC), and when the Printhead Motor signal isoff, the reading goes high (5VDC).1-24 Service Manual