MX8000 Installation and Operation Guide
3–10
3. Disconnect the backup battery. (See Figure 3–14.)
4. On the back of the receiver remove the four screws that hold the CPU, PS, User Interface Assembly to
the chassis. (See Figure 3–11 for screw locations.)
Screw
Locations
COM 1
PARALLEL
100 VA
120 VAC ± 10%
240 VAC ± 10%
50-60 Hz
WARNING!
HIGH VOLTAGE PRESENT
DISCONNECT AC LINE AND
ALL OTHER CONNECTORS
PROIR TO SERVICING
FUSE
2.5A
SLOW BLOW
REPLACE ONLY
WITH A FUSE
OF SAME TYPE
UNUSED
RLY NO
RLY COM
BATT-
BATT+
RLY NC
COM 2
RELAY RATING
2.5A 48VAC/VDC
Figure 3–11: CPU, PS, User Interface Assembly Retaining Screw Locations
5. From the front of the receiver, pull the CPU, PS, User Interface Assembly out of the receiver chassis
6. Switch the power supply select switch to the up position. (See Figure 3–12.)
7. Slide the CPU, PS, User Interface Assembly back into the receiver chassis.
8. On the back of the receiver replace the four screws that hold the CPU, PS, User Interface Assembly in
place. (See Figure 3–11.)
115V
240V
Power Supply
Select Switch
Power
Supply
Mother
Board
Fuse
Holder
Power Cord
Connector
User
Interface
Figure 3–12: Side View of CPU, PS, User Interface Assembly
9. Reconnect the AC power cable.
10. Reconnect the back-up battery. (See Figure 3–14.)
11. Replace the front plate by screwing in the front plate retaining screws. (See Figure 3–1.)
3.11.2 How to Verify Earth Ground
To verify earth ground at the AC outlet the MX8000 receiver is powered from, use the following steps:
1. Measure the AC voltage between the center ground post and each side of the outlet (see A & B in Figure
3–13). You should read approximately 120 VAC at measurement point B and nominal VAC at
measurement point A.
2. Measure the voltage between the two slotted holes. It should be equal to the voltage reading at
measurement point B. (See Figure 3–13.)
If these voltages are not equal, the outlet does not have a proper earth ground.
3. Ground the outlet by running a wire (18 gauge or higher) to a good earth ground.
The wire should be of equal or greater diameter to the wires used to feed the outlet. It may be necessary to
have a licensed electrician ground the outlet.
