Samsung DX-408 Installation Manual page 32

Chapter 2
2-16
DX-408/DX-408i Digital Key System Installation
Terminating Resistors for DX-408i Trunks
Note that 100 Ω terminating resistors must be used for ISDN connections. These must be
placed across each of the send and receive pairs. Note that for the second BRI channel 100 Ω
resistors are located on the 2BRI board and are able to be switched in and out (refer to S101).
These are placed on the second channel in order to provide 100 Ω terminations when the
channel is used as 2 ISDN extensions. These terminations are required for ISDN extensions.
These resistors should be switched across the pairs for the second BRI channel when used as
ISDN Trunks; however, it is necessary to provide external terminating resistors for the first BRI
channel.
The position of the switch settings in the ON setting (ie. terminating resistors
switched across the pairs) is clearly marked on the BRI card.