User Manual

Mission Valley Radio Repeater Equipment + Upgrade
User/Maintenance Handbook
Handbook No. 50-078021HBKM Page 68 of 85
7.3 Care of Modules
7.3.1 General Comments
Many of the active modules contain semiconductor devices utilising MOS technology, which can
be damaged by electrostatic discharge. Correct handling of such modules is mandatory to ensure
their long-term reliability.
To prevent damage to a module, it must be withdrawn/inserted with care. The module may have
connectors on its underside, which might not be visible to the service operative.
7.3.2 Module Removal (LNAs, general procedure):
The following general instructions should be followed to remove a module:
1 Remove power to the unit
2 Remove all visible connectors (RF, DC & alarm)
3 Release module retaining screws.
4 Slowly but firmly, pull the module straight out of its position. Take care not to twist/turn the
module during withdrawal. (When the module is loose, care may be needed, as there may be
concealed connections underneath).
7.3.3 Module Replacement (general):
1 Carefully align the module into its location then slowly push the module directly straight into its
position, taking care not to twist/turn it during insertion.
2 Reconnect all connectors, RF, alarm, power etc.,(concealed connectors may have to be
connected first).
3 Replace retaining screws (if any).
4 Double-check all connections before applying power.
7.3.4 Power Amplifiers
1) Remove power to the unit. (Switch off @ mains/battery, or remove DC in connector)
2) Remove alarm wires from alarm screw terminal block or disconnect multi-way alarm
connector.
3) Carefully disconnect the RF input and output coaxial connectors (usually SMA)
If alarm board removal is not required, go to step 5.
4) There is (usually) a plate attached to the alarm board which fixes it to the amplifier, remove its
retaining screws and the alarm board can be withdrawn from the amplifier in its entirety. On
certain types of amplifier the alarm board is not
mounted on a dedicated mounting plate; in this
case it will have to firstly be removed by unscrewing it from the mounting pillars, in most
cases, the pillars will not have not have to be removed before lifting the amplifier.
5) If the amplifier to be removed has a heatsink attached, there may be several different ways it
can have been assembled. The most commonly used method, is screws through the front of
the heatsink to threaded screw holes (or nuts and bolts), into the amplifier within the main
case. If the heatsink is mounted on the rear of the main case (e.g., against a wall in the case
of wall mounted enclosures), then the fixing method for the heatsink will be from within the
case, (otherwise the enclosure would have to be removed from the wall in order to remove the
heatsink).
When the heatsink has been removed, the amplifier may be unscrewed from the main casing by its
four corner fixings and gently withdrawn.
Fitting a new power amplifier module will be the exact reverse of the above.
Note: Do not forget to apply fresh heatsink compound to the heatsink/main case joint and
also between the amplifier and the main case.