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Setting to work
6
Close the rear door on the Transceiver Unit.
Related topics
Setting to work summary, page 206
Powering up the MS70 for the first time, page 219
Adjusting the output voltages from the power supply modules
If you need to adjust the output voltages from a power supply module, this must be done
while measuring the voltage on the TRXU Terminal block in the Transceiver Unit. This is
necessary because you need to compensate for any voltage drop in the power cables.
Prerequisites
Two people are required to do this task.
The MS70 is switched on and working in normal operational mode.
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. In order to filter out voltage variations caused by noise or load variations, large
capacitors are connected to each of the +12 VDC and +6 VDC supplies. These capacitors
are physically located in the three TRXU subracks in the Transceiver Unit.
The DC cables from each of the three Power Supply Units to the Transceiver Unit are
all separate conductors in a bundle. 230 Vac is also included in order to power the fans
in each TRXU subrack.
227
331549/C
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