Kyocera KM-4230 Service Manual page 151

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On the operation unit main PCB (OMPCB), the major component is the CPU IC19,
which directly controls the operation of the machine in response to a control program
located in EPROM IC12 and executed from SRAM IC9. EPROM IC16 contains font data
for the LCD display and LCD controller IC11 controls the LCD panel display from
instructions contained in SRAM IC20.
The operation unit right PCB (ORPCB), consisting of key switches and LEDs, is
controlled by scan signals and LED lighting signals from the operation unit main PCB
(OMPCB).
The operation unit left PCB (OLPCB) consists of key switches, LEDs and the CFL
lighting drive circuit. Key switches and LEDs are controlled by scan signals and LED
lighting signals from the operation unit main PCB (OMPCB), and the CFL lighting drive
circuit. This circuit generates AC power for CFL lighting drive and is controlled by the
turning on and off of CFL lighting signals by the operation unit main PCB (OMPCB).
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