ADC ISDN NT11010 - Manual (Page 17)

9
Internal jumper settings
The 1010 is shipped with 100
Ω
Termination Resistance (TR). This TR is added to
the S/T bus when dip switches 1 & 2 are set to the on position. If the installed S/T
bus ISDN CPE provides 100
Ω
TR, dip switches 1 & 2 should be set to the off posi-
tion to provide 0
Ω
. When the ISDN CPE provides 50
Ω
, the 1010 needs to be
adjusted to provide the other 50
Ω
, instead of its default of 100
Ω
. Changing the 1010
TR is done through an internal jumper. Following is the procedure to change the
internal jumper.
WARNING!
Always disconnect all telephone lines at the network interface,
and power connections from the wall outlets before servicing
or disassembling this equipment.
1 To open the 1010, remove the four corner screws from the bottom of the
1010.
2 On the component side of the printed circuit board, locate JP3 & JP4 (in
the middle of the board). Table 5 shows the setting of the dip switch 1 & 2
for different Termination Resistance settings.
Table 5—Jumper setting for termination resistance
* factory default
Dip Switch
1 & 2 JP3 & JP4
not jumpered JP3 & JP4
jumpered
ON * 100 ohms * 50 ohms
OFF 0 ohm 0 ohm