Power Distribution And Control; Memory Back-Up - Ricoh A193 Service Manual

OVERALL MACHINE CONTROL
The basic Fax Unit consists of two PCBs: an FCU and an NCU.
The FCU controls all the fax communications and fax features, in cooperation
with the base copier's main board, the BiCU. The NCU switches the analog
line between the fax unit and the optional external telephone.
Fax Options
1. G4 unit: This allows the Fax Unit to communicate over an ISDN
(Integrated Services Digital Network) line.
2. Function Upgrade Card: This expands the system's SRAM capacity to
hold programmed telephone numbers, communication records, etc. Refer
to page 1-5.
3. Feature Expander - 2M/4M: This expands the DRAM's capacity to hold
up to 3MB or 5MB of received data or data for transmission. Also, some
additional features become available when the Feature Expander is
installed.
4. Feature Expander - Hard Disk: This extends the image data capacity to
80MB. Also, some additional features become available when the Feature
Expander is installed.
5. Page Memory Card (High Resolution Card): This enhances the scan and
receive resolutions to up to 400 x 400 dpi. Without this card, only
'Standard' and 'Detail' resolutions are available for both transmission and
reception.

3.2 POWER DISTRIBUTION AND CONTROL

The FCU is supplied from the base copier's BiCU (+24V, +12V, -12V, and
+5VE) and PSU (+5V). Refer to the base copier's service manual for details.

3.3 MEMORY BACK-UP

The system parameters and programmed items in the SRAM on the FCU and
the SRAM on the Function Upgrade Card are backed up by a battery
(long-term backup), in case the base copier's ac switch is turned off.
Note: The data in the SRAM is not guaranteed if the card is disconnected
from the machine. Whenever the Function Upgrade Card needs to be
removed, follow the instructions in the software upload and download
procedures in the Service Level Functions section to avoid any data
loss.
The SAF memory DRAM on the FCU board and the Feature Expander Card
are backed up by a rechargeable battery for 1-hour.
SM 1-8 (A639)