Hardware manual

Issue 8 Electra Elite
5 - 10 Installing Electronic Telephone Units
3.1.4 Connectors
Before programming System Data, the battery must be
connected to CN4 to allow memory retention if a power
failure or brownout occurs. If a brownout or power failure
does occur, and the battery backup circuit is not activated,
System Data resets to the default values, all stations in
the system reset to the default values, and all data
programmed on individual stations is cleared.
When a CPUB( )-U( ) ETU is installed in the system, the
clock/calendar must be set. This also applies when
battery backup fails for any reason.
When CPUB( )-U( ) ETU is removed for long term storage,
disconnect the battery from CN4. This prevents the
battery from discharging completely. The fully charged
battery retains memory for approximately 21 days.
The CPUB( )-U( )ETU has the following connectors:
CN1 Connects to the backboard
CN2 Connects to the ISA-bus
CN3 Connects to CN2 on the EXP-U10 ETU
using the expansion cable
CN4 Connects to the memory backup battery
using the battery cable (factory installed)
CN5 Connects to CN1 of the CLKG-U( ) Unit
CN6 Connects to CN2 of the CLKG-U( ) Unit
3.1.5 LED Indications
Table 5-2 CPUB( )-U( ) ETU LED Indications
LED Description On Flashing Off
LIVE CPU status Operation stopped
(Power On)
Normal Operation No Power
LED2 Power status System Power On Not Used System Power Off