Service manual

POWER SUPPLIES
9-11
March 2000
Part No. 001-3139-502
9.8 VOTER SHELF POWER SUPPLY (-501)
The -501 Voter Shelf Power Supply has a 90-
264V AC 47-63 Hz input and 4 sets of 4 continuous
duty outputs as follows:
+5V DC 15A.
-5V DC 2A.
+12V DC 2A.
-12V DC 2A.
The -501 power supply can handle 4 Voter
Shelves. The -501 has:
4 separate +5V 15A connections.
4 separate -5V connections.
4 separate +12V connections.
4 separate -12V connections.
4 separate +12V Auxiliary connections.
4 ground connections plus ground bar.
9.9 REDUNDANT POWER SUPPLY
The voter power supply drawer is made redun-
dant by the use of a second power supply. The fuse
board allows two power supplies to share the load via
diodes. One of the power supplies may be removed
and the remaining power supply will supply the full
load (see Figure 9-7.)
9.10 POWER CONSUMPTION
The voltage, current and power for each supply
voltage per card is shown in Table 9-3.
Total watts for a module is 6.03W. The following
formulas are used to find the BTUs per hour. The total
wattage of the voter system is found by multiplying
the wattage (6.03W) by the number of modules.
Watts x Number of Modules = Voter Power
The wattage required by the power supply is
found by dividing the total wattage of the Voter by the
efficiency (0.7) of the power supply.
Voter Power ÷ 0.7 = Wattage of the Power Supply
The BTUs per hour are found by multiplying a
known value (3.6) by the wattage of the power supply.
3.6 x Wattage of the Power Supply = BTU per hour
Example:
6.01 x 13 = 78.13W (Voter Power)
78.13 ÷ 0.7 = 111.6W (Wattage of the Power Supply)
3.6 x 111.6 = 401.76 BTUs per hour
9.11 VOLTAGE ADJUSTMENTS
9.11.1 -501 SUPPLY
See Figure 9-5 for location of components and
Figure 9-8, Figure 9-9 and Figure 9-10 for wire con-
nections.
After all the Voter shelves are connected to the
power supply:
1. Connect the 5V Sence wire (Grn/Yel), to the 5V line
on the back plane of the appropriate Voter shelf. (In
a 2 or 3 shelf system, connect the 5V sense line to
the second shelf. In a 4-shelf system connect the 5V
sence line to the third shelf.)
2. Turn one of the power supplies OFF.
3. On an RVM, connect a voltmeter to U1, pin 76
(DO NOT use an extender card).
4. Adjust the +5V pot on the back of the power supply
for a reading of 5.1V (see Figure 9-12).
5. Check the voltage at 5V jack on the back of the
power supply. The reading should be close to 5.1V.
6. Repeat the process for the second power supply.
7. Turn both power supplies ON.
Table 9-3 POWER CONSUMPTION
Voltage Current Power
+5V DC
-5V DC
+12V DC
-12V DC
0.80A
0.07A
0.08A
0.06A
4.00W
0.35W
0.96W
0.72W