10
MICRONTU G.703 CARD (120 OR 75 OHM)
Table 3-1 shows the factory-default jumper settings for the 120-ohm rear card.
Following Table 3-1 is a description of each jumper’s function and possible
settings. When configuring the jumpers, take care not to lose the individual
straps.
Table 3-1. Summary of default jumper settings
for 120-ohm rear card
120-Ohm Rear Card Jumpers
Jumper
Function
Factory Default
LK1
TX Pin 4 to GND
Strap Off*
LK2
RX Shield (Pin 3) to GND
Strap Off
LK3
RX Pin 2 to GND
Strap Off*
LK4
Clock Synchronization
Strap Off
LK5
(DTE) SGND to FGND
Strap On
*Mandatory setting. All others are up to user’s discretion.
LK1: (Transmit Pair) Pin 4-to-Ground Connection
This setting determines whether or not pin 4 of the transmit pair is sent to
earth ground. This connection should
not
be made in most cases.
LK1
Setting
Strap On
Pin 4-to-GND Connection Made
Strap Off
Pin 4-to-GND Connection Broken
LK2: (Receive Shield) Pin 3-to-Ground Connection
This setting determines whether or not the RX shield (pin 3) is connected to
earth ground. This connection may help EMC performance in some cases.
LK2
Setting
Strap On
Pin 3-to-GND Connection Made
Strap Off
Pin 3-to-GND Connection Broken
