Lexmark T620 Service Manual - Page 204

4069-5XX/7XX mechanically installed under the printer. Communication between the option and the base printer stops when you remove an option located above or below the printer. The printer no longer recognizes the option and deletes associated messages. Each installed option below the base printer provides an electrical autoconnect to the option attached below it. The output expander option attached above the base printer provides power to the option above it. We do not recommend to attach or "Hot Plug" any options with the base printer power turned On. Duplex Option The duplex option interface is a six pin autoconnector that provides a +24 V dc, +24 V dc return, serial interface transmit signal, serial interface receive signal and two ground pins. The duplex option receives the +24 V dc from the base printer for the duplex motors and also converts the voltage to +5 V dc for duplex electronics. Duplex chassis grounding is provided from the printer to the duplex option through a ground spring attached to the frame and base of the printer. The ground connection is automatically made when the option is installed below the printer. The paper input sensor is located in the rear of the duplex unit under the input paper guide. The rear cover open switch is located on the rear cover assembly. The paper exit sensor is located on the left frame assembly. The jam removal tray open switch is located at the end of the left frame assembly. There are no switches in the level 2 duplex option. Option Microcode The options are "Smart Options" or options that have a system board. The option system board has a microprocessor that controls the option mechanism. A software architecture is provided that controls the option and communicates information such as paper path status, sensor or switch status, motor status and so on to the base printer. 3-38 Service Manual