User guide

Chapter 2 – Installing the Modem
Multi-Tech Systems, Inc. MT9234ZBA-Series User Guide 9
Changing the Internal Jumpers
This step is required only if:
● You intend to use the modem on a leased line.
● You intend to add a monophonic external speaker to your modem with the voice option. No changes are
needed for stereo.
This will require you to open the modem and move one or more jumpers on the modem’s printed circuit board.
Warning: The following procedure must be performed by authorized service personnel.
Caution: The circuit board can be harmed by static electricity. Before you open the case, touch a grounded
object, such as the metal chassis of your computer, to discharge any static electricity in your body,
then touch the metal shell of the modem’s RS-232 connector to ensure that there is no voltage
difference between you and the modem.
Opening the Modem
1. If the modem is connected, turn it off and remove all connecting cables (including the power and line
cables).
2. Turn the modem upside down.
3. On the bottom of the modem are two screws, which hold the case together. Remove both screws and set
them aside.
4. Turn the modem right side up.
5. Before touching anything inside the modem case, discharge any static in your body by touching a piece of
grounded metal such as the computer chassis. Electrostatic discharge (ESD) is the release of stored static
electricity that can damage electrical circuitry or components. Static electricity is often stored in your body,
and discharged when you come in contact with an object of a different potential.
6. Perform the procedure below described in this section only at an ESD workstation using an antistatic wrist
strap. If such a station is not available, you can provide some ESD protection by wearing an antistatic wrist
strap and attaching it to a metal ground screw (lug).
7. Remove the top part of the modem case.
Location of the Jumpers