Measuring the power supply output voltages in the Power Supply Unit
The best way to check the operation of the individual power supply modules is to measure the output voltages. The output voltages can be measured on the terminal block on each power supply module. However, due to space limitations, it is better to check them on the terminal block on the left wall in the Power Supply Unit.
Prerequisites
The MS70 is switched off.
You must be equipped with a standard set of tools. This tool set must comprise the normal tools for electronic testing, as well as the necessary tools for relevant disassembly/assembly for test access. Each tool must be provided in various sizes. We recommend that all tools are demagnetized to protect your equipment.
You need the following test equipment:
•  Multimeter
WARNING
High voltages are used. This equipment must only be serviced by qualified personnel familiar with the construction and the operation of the MS70, as well as the potential hazards involved. Failure to observe this precaution could result in bodily injury.
Context
The outputs from the three power supply modules are connected to the terminal block on the left cabinet wall. The output from the +75 VDC power supply is fed through an NTC resistor. The Sense inputs on the power supplies are not used. These inputs are connected to the output terminals.
Image
A PSU Terminal block (on the left side of the Power Supply Unit)
B TRXU Terminal block (on the rear side of each subrack inside the Transceiver Unit)
C Power supplies
D The cables from the TRXU Terminal block are connected to the Power Connector Panel on the rear side of the TRXU subrack.
E The power cables are run in steel conduits.
F This symbol means that the terminals are connected with a conductive rail.
Note
The output from the +75 VDC power supply is fed through an NTC resistor.
The following requirements must be met:
•  +6 VDC (Approximately)
•  +12 VDC (Approximately)
•  +75 VDC (Approximately)
Procedure
1 Open the cabinet door.
2 Observe the terminal block on the left side of the cabinet.
3 Turn on the Power Supply Unit locally.
a Turn on the Processor Unit and start the MS70 program.
b On the Setup menu, select TRU On/Off.
c In the TRU On/Off dialog box, select Start.
This will turn on the entire system, but since you have disconnected the power cables on the rear side of the Transceiver Unit, it will not be activated. Disregard any error messages that may appear.
4 Measure the individual voltages while the MS70 is turned off.
Verify that the voltages are approximately:
•  +6 VDC (Approximately)
•  +12 VDC (Approximately)
•  +75 VDC (Approximately)
5 Turn off the Power Supply Unit.
a On the Setup menu, select TRU On/Off.
b In the TRU On/Off dialog box, select Shutdown.
6 Close the cabinet door.