Rockwell Automation 1772-LV,D17726.6.1 A and I MNL MINI-PLC-2/15 PROCESSO - Manual (Page 74)

Maintenance and Troubleshooting
Chapter 5
5Ć4
1. Remove AC power from the System Power Supply using the main
disconnect.
2. Remove the fuse cap by pushing in slightly and turning counterclockwise.
The fuse cap and the fuse holder will pop out of the fuseholder.
3. Install the replacement fuse (1 amp for 120V AC; 0.5 amp for 220/240V
AC) in the cap and insert into the fuse holder. Push in and turn the fuse
cap clockwise to seat in the fuseholder.
4. Restore system power.
Power Supply and I/O Power Cable Voltage Measurements
Output voltage measurements can be made at the base of Power Supply and at
the end of the I/O Power Cable where it connects to the I/O Chassis backplane
to determine whether power is getting to the backplane. Although
measurements do not provide a complete diagnosis of the Power Supply, they
can identify problems during troubleshooting. A voltmeter, accurate to +1%,
can be used for these measurements.
The pins at the Power Supply socket and the end of the I/O Power Cable are
numbered 1 through 9 as shown in Figure 5.2. The voltages for the pins are
also listed. Note that pins 6 and 9 cannot be measured directly with a voltmeter.
Follow these steps to measure the voltage at the Power Supply socket:
1. Turn the Processor’s Mode Select Switch to the PROG mode. To support
Processor memory, be sure there is battery backup or a programmed
EPROM in place. if not, be sure there is a copy of the program on
magnetic tape for convenient reloading.