Motorola Starline SG 2000 - Figure 3-5 SG2-PS2 Power Supply

3-6 Bench Setup
SG 2000 Installation and Operation Manual
Note that no damage results if the jumper is not changed. In a 90 Vac system, changing the jumper
ensures that the dc supply does not turn on until the proper input voltage level is reached. This
prevents excessive loading of the cable plant power supply during turn-on after a power-off situation.
Figure 3-5 illustrates the location of the
LO-HI jumper:
Figure 3-5
SG2-PS2 power supply
SG2-PS2
CAUTION
NO USER SERVICEABLE PARTSINSIDE ASSEMBLEDINMEXICO
SEE INSTALLATION MANUAL FOR SERVICE
VOLTAGES IN EXCESS OF
300 VOLTSARE PRESENT
UNDER COVERAND MAY
BE PRESENT AFTER POWER
IS REMOVED
LO HI
24V 5V
ADJ
TEST
POINT
TEST
POINT
A second, optional dc power supply located in the lid of the SG 2000, offers full redundancy. Both
power supplies are on-line continuously and share the current load. In the event one supply fails, the
other assumes the entire load with no disruption of service. Each dc supply can deliver 4.3 A at
+24 V and 0.69 A at +5 V. Test points are provided for 24 Vdc and 5 Vdc supplies. Green LEDs—
two on each power supply and one on the RF chassis—indicate the overall health of the nodes dc
power bus. The power supply is factory calibrated for 24 V and should not need output voltage
adjustment. Power supply adjustment R51 is available but should be used only by qualified
personnel. When dual supplies are used, the supply with the lower output voltage sets the output
voltage of both supplies. Adjusting R51 on the other supply appears to have no visible effect.
However, if the “leading” supply fails, the misadjusted supply undergoes a sudden, large voltage
change. Figure 3-5 illustrates the location of R51 (
ADJ).
The ac input from the feederline to the power supply must be between 44 V and 90 Vrms with a line
frequency of 50 Hz or 60 Hz. The wave shape of the input voltage must be quasi-squarewave. The
power supply features a self-protection attribute that shuts it down for instantaneous line voltages
between 112-142 Vrms. A precision output regulator protects against overcurrent and short circuits,
thus providing a precise output voltage.
By selectively positioning a jumper (JP1) on the SG 2000 lid motherboard (LIDB), the power supply
can be configured to conform to different power requirements. Figure 3-1 illustrates the location of
jumper JP1 and Figure 3-3 illustrates the schematic.
The following subsections explain the powering options.