Flash Memory; Sdram; Sensor Input Circuit; Paper Empty Sensor - Ricoh B173 Service Documentation

MAIN BOARD

6.4.2 FLASH MEMORY

It keeps the system program and downloads the system program through the PC
interface.
• Capacity: 0.5 M Byte
• Access Time: 70 nsec

6.4.3 SDRAM

Used as a buffer, system memory area at the time the machine prints.

6.4.4 SENSOR INPUT CIRCUIT

Paper Empty Sensor:

The paper empty sensor (Photo Interrupter) on the engine board lets the CPU
know if the tray has paper. If the paper tray is empty when it reads the D0 Bit of
CPU, it sets the second LED (yellow) on the panel.

MP Sensing:

The MP Sensor (Photo Interrupter) uses an actuator to let the CPU know if paper is
in the manual paper (MP) tray.

Paper Feed and Toner Cartridge Sensor:

When paper passes the actuator (feed sensor part), it detects the photo interrupter
signal. Then lets the CPU know the paper feed condition. Then it sends image
data. If it doesn't detect the feed sensor in 1 sec. after paper is fed, Jam 0 is shown
(Red and yellow LED's will be set on). The machine checks if the cartridge is
installed. The actuator operates after the cartridge is attached. The signal from the
photo interrupter is detected when it passes the actuator of the sensor part. This is
the developer ID sensing procedure.

Paper Exit Sensor:

Checks if paper had exited from the machine. The exit sensor on the engine board
and actuator on the frame are used for this process. Paper detects the on/off time
of exit sensor. Then either a correct operation or a jam information is sent to the
CPU.
B173 6-8 SM