150-402-102-01, Revision 01
Appendix A: Additional Technical Information
HRU-402 List 2
July 27, 1998
49
Figure 25.
HRU-402 List 2 Block Diagram
Local and Line Powering
The HRU-402 List 2 can be line or local powered. The remote unit always
chooses the local -48 Vdc power source from the power supply attached to
pair 35(-) and 17(+) of the card-edge connector (
).
To set local or line power for the remote unit, switch the local power (LPWR)
switch (S1) to ENA (see
for switch location). When LPWR is set to
DIS, the HRU must be line powered. The earlier versions of the HLU-231
(Lists 1, 2, 3, 3A and 4) must first have their PWRF user option set to DIS
when connected with a locally powered HRU-402 List 2 unit. When enabled,
local power automatically takes precedence over line power. If local power is
lost, the remote unit reverts to line power.
