HP 2605 Service Manual - Page 66

Engine control system Basic sequence of operation The operational sequence of the printer is controlled by the microcomputer on the DC controller printed circuit assembly (PCA). The purposes of each period, from power-on until the main motor stops after the completion of printing, are listed below. See General timing chart on page 80 for a detailed timing chart. Table 4-1 Basic operational sequence Period Purpose Remarks WAIT (wait period) From power-on until the end To clear the drum surface of the main motor initial drive. potential and to clean the ETB. Detects whether or not the print cartridge is installed. STBY (standby period) From the end of WAIT or LSTR until the input of print command from the formatter. Or, from the end of LSTR until power-off. To keep the printer ready to print. INTR (initial rotation period) From the input of print command from the formatter until the pick-up solenoid is turned on. To stablize the photosensitive drum sensitivity for print preparation. PRINT (print period) From the end of INTR until the developing high-voltage is off. To form the image on the photosensitive drum based on the VIDEO signals input from the formatter, and to transfer the toner image onto paper. LSTR (last rotation period From the developing highvoltage off until the main motor stops rotating. To deliver the last page completely. Also used to clean the ETB. The printer enters INTR after the end of LSTR, when the print command is input from the formatter. The engine control system coordinates all printer functions. It drives the laser/scanner system, the image formation system, and the pickup and feed system. The engine control system contains the following components: ● DC controller PCA ● Low-voltage power supply unit ● High-voltage power supply PCA 56 Chapter 4 Operational theory ENWW