33
Installation of System Components
Power Connections
The Digital Tone Remotes must be properly grounded. The simplest method for proper
grounding is to use Zetron's 13.5VDC switching power supply (P/N 802-0692) in a
grounded outlet. This power supply accepts 100VAC to 240VAC, uses an IEC power
connector, and is certified in several countries.
If you are not using the power supply mentioned above, then you must supply your own
AC or DC power (or both for DC standby) and a separate grounding wire. For AC power,
attach the leads of the 12 volt AC wall transformer to the connections labeled “AC1” and
“AC2” of the terminal block “TB3”. For DC power or DC standby, connect 12 volt DC
power to the connections labeled “DC+” and “GND” on terminal block “TB3”.
Regardless of AC or DC power, an earth ground connection must be made to one of the
“GND” terminals of “TB3”.
For location and pinout of terminal TB3, see
External Audio Connections
The deskset has a built in front panel microphone and speaker. Should an external audio
interface like an external speaker or a desk mic be required, connections for microphone,
speaker, and PTT have been provided on the terminal block “TB3”. The speaker output
“SPK” is a low level output that follows the front panel volume control. It is for driving a
headphone speaker, or other amplified speaker. It does not have the power to drive an
external speaker directly. To disable the front panel speaker, put the connector “P4” in the
B position. The microphone connection “MIC” is a high impedance (10 k
) line level
input, which is intended for connection to a dynamic microphone element. The trim-pot
R81 sets the gain of this input from 1/10 to 30 times. Adjust it so that U13 pin 3 has
approximately 1 Volt peak-to-peak of speech. JP6 should be in Position B when using this
input. There is also a “PTT” input that will activate transmit when grounded, for
connection to a desk mic or foot-switch.
In a Model 284, if an external unselect audio speaker is to be used, it is connected in place
of the Line 4 TX pair (Line 4 cannot be used in this configuration). Connect the amplified
speaker to the terminals labeled “2W-4” and “2W+4” of terminal strip “TB2”.
Caution!
To prevent induction of high frequency signals from the circuit
board electronics, interface wires should not be allowed to
drape over the circuit board, but instead should be routed
directly toward the access at the bottom of the unit.
!
Caution!
For DC Standby applications, the DC power supply level should
not 14 volts.
!