SX PARTS CATALOG

DIAGRAM 930
DC Controller PCB Assemblies

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The DC Controller is the Central Processing Unit for all electromechanical functions of the printer mechanism. It receives commands and video data from the Video Controller and outputs signals to the Laser Scanner, High Voltage Transformer, and paper movement electronics. Status signals are sent back to the video controller upon request. The DC controller is capable of producing a test pattern on its own, but it does not have enough memory to format pages (which is the function of the video controller). Status panels are driven by the DC Controller, but control panels with operator input functions are connected to the Video Controller.

The difference between 240-, 300- and 400-dpi printers is merely a crystal-based oscillator circuit. The HP LaserJet III has two versions: RG1-1969 and RG1-2706. RG1-1969 is similar to RG1-0710, but it has no bottom pan safety switch. RG1-2706 is the new surface-mount LSI version, which was used on the later production LaserJet IIIs. RG1-2706 requires DC power supply number RG1-1310 or higher (Diagram 910). Also, the old version PostScript cartridge, 33439P, is not compatible with the new DC controller RG1-2706.

The Apple LaserWriter II controller is basically the same as the more common HP or other SX versions. The difference is the orientation of the video interface connector. The Apple version uses a right angle connector and the standard version uses a vertical connector.

The RX and TX printers use completely different controllers from the SX printers. The following table lists controllers for most of the SX, RX and TX family.