Canon Super G3 Fax Board-J1 Service Manual

Canon Super G3 Fax Board-J1 Service Manual Manual pdf 19 page image

COPYRIGHT © 2001 CANON INC. 2000 2000 2000 2000 CANON SUPER G3 FAX BOARD-J1 REV.0 JUNE 2001CHAPTER 2 BASIC OPERATION2-43 Off-hook detection PCB3.1 Block Diagram of the Off-hook detection PCBF02-301-013.2 Functions of the Off-hook detection PCBPower Supply Circuit Used to Detect an ExtensionTo detect the connection of an extension, the Off-hook detection PCB generates a DCvoltage of +48 V to supply to the extension terminal. A transformer is used to separate theprimary side and the secondary side by an electrical means.All-Day Power Supply CircuitThe main controller circuit generates all-day 5 VB from all-night +3.3 VB. To operate theFC detection circuit of the G3 fax control PCB at all times, the +5 VB voltage is sent tothe G3 fax control PCB by way of the Off-hook detection PCB.Off-hook detection PCBPower supply circuit fordetection of extensiontelephoneAll-day power supplyrelay circuitJ713 J714J712 J715Fromcomposite powersupply PCB+24VFrommain controllerPCB5V all-dayvoltagesupplies voltage fordetection of off-hookstate5V all-day powersupply