Ricoh A230, Service Manual, Page: 668 / 1134

OVERALL MACHINE CONTROL
1-8
A230/A231/A232 SM
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. ISDN unit: This allows the fax unit to communicate over an ISDN (Integrated
Services Digital Network) line.
2. EXSAF board: This expands the SAF memory capacity to hold up to 6MB of
received data or data for transmission. Also, some additional features become
available. In addition, this expands the system's SRAM capacity to hold
programmed telephone numbers, communication records, etc.
3. PMU board: This expands the page memory capacity to 4MB to enable 400 dpi
communications. Also, JBIG compression becomes available.
4. Hard Disk: This expands the SAF memory capacity to 130MB. The EXSAF is
required to install this option.
1.3.2 POWER DISTRIBUTION AND CONTROL
The FCU power 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.
1.3.3 MEMORY BACK-UP
The system parameters and programmed items in the SRAM on the FCU and the
EXSAF board are backed up by batteries (long-term backup), in case the base
copier's main switch is turned off.
The SAF memory (DRAM) on the FCU and the EXSAF board are backed up by
rechargeable batteries for 1 hour.