Key Service Unit; Power Supply - Comdial DX-80 Installation & Maintenance Manual

Key Service Unit

The DX-80 Key Service Unit (KSU) is a modular flat-pack design. Two KSU's (KSU1 and KSU2) may be
equipped to achieve the total system capacity of 16 CO lines, 56 Extensions (48 digital and 8 analog) and 8
Voice Processing Channels. KSU1 is factory equipped with one 408M, one APM4 and the CPM (Central
Processor Module). KSU2 is factory equipped with one 408E. Each KSU is a self-contained cabinet with
internal power supply. The power supply AC transformer can be hard-wire selected for either 117vac or
230vac operation. (It is shipped wired for 117vac operation.) The KSU is designed to be mounted on the
wall and is shipped with a wall mounting template. The compact KSU weighs less than 20 pounds and is UL
Listed.
Panels installed over various KSU openings may be removed or repositioned to accommodate exterior
connection requirements. Three such panels are present. One may be removed to route a serial cable
through the KSU outer housing for connection of ancillary SMDR equipment. Another may be removed to
route a serial (NULL Modem) cable through the KSU outer housing for direct connection of a PC for on-site
PC-DBA programming. One KSU opening panel may be removed or repositioned to accommodate cable
entry requirements through the outer housing for connection of station/extension cables or to the MDF.
From the exterior, with covers in place, KSU1 and KSU2 look identical. However, KSU1 contains the Central
Processor Module (CPM) (system call processing).

Power Supply

The power supply circuitry of the DX-80 incorporates a linear design AC transformer with a choice of input
voltage taps. The transformer primary windings are shipped wired for 117vac applications. A factory
insulated tap wire may alternately be connected for 230vac applications. Since the power supply is linear in
design, the output voltage varies between 21.6vdc and 32vdc depending on load and stability of the input
voltage. The output voltage is delivered to the 408M (in KSU1, 408E in KSU2) for voltage regulation. All
system operation and logic voltages are produced at the 408M/E.
Two fuses are equipped on the power supply board, one for ac input over-voltage protection and one for DC
output over-current protection. A main power switch is accessible when the KSU cover is in place. In the
event battery backup operation is desired the KSU power cord can be connected to a external (ancillary)
UPS (Un-interruptible Power Supply). It is the responsibility of the installer to match the battery
requirements/UPS requirement to the specific needs of the equipment owner.
To determine the battery requirement needs and UPS requirement use the chart in Specifications (this
section) to find the current draw and necessary Amp/Hour back up support that the battery/UPS is to supply.
P7290 IMM
DX-80 I M
NSTALLATION AND AINTENANCE
Figure 1: DX-80 Key Service Unit
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M
ANUAL