Brother MFC-9420CN Service Manual page 72

(4) Interface Control
<General>
1) Interface type
This document describes the video and command/status Interface between video
controller and engine controller. Printer controller acts as a slave to video controller.
Through video interface, video controller controls the printer & operator panel using
command/status communication and transmits the synchronized video data to printer
laser diode. Operator panel is physically resident on the engine.
2) Interface connection
The interface connector of this machine is connected to the host system as shown
in Fig.3-37.
Operator
Panel
Video Interface/DC Power Supply Connector
Duplex unit
(Option)
Lower Feeder
Unit (Option)
Interface Circuit (Internal Connecting System)
Printer
Engine
Controller
DC Power Supply
Fig. 3-37
3 - 3 8
Video Controller
+5V (1A max)
+3.3V (1A max)
Host
System
Confidential