Xerox Phaser 3450 Service Manual page 147

CIRCUIT DESCRIPTION
11.2.4.11 PTL Circuit
PTL circuit is located in the Video Controller Board and applies NPN type TR for drive
11.2.4.12 Panel Circuit
Panel is consisted of 2*16 LCD(with back lite), 1 LED, and 6 keys. It has HT48C5A that is 8bit I/O control MCU, it supplies
clock (7.37MHz), and it controls data with CPU by UART method.
LCD back lite for supply needs +5V, and logic for control needs +3.3V. TXD, RXD, and Reset signal are used. Back lite
is operated with 240mA, and LCD dot is controlled by VEE voltage.
11.2.4.13 SCF Circuit
In SCF circuit, 6.9MHz clock is supplied to 8bit CPU 4616. SCF circuit controls step motor, solenoid clutch, Regi. clutch,
and paper size function & empty function.
It operates with controller and SIO method. PPS controls motor speed and it is downloaded to RAM to operate and control
the circuit in controller. U18 9/10/11/116 pin signal, control signal, make it to operate.
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