User's Manual

Manual 7-9375-4 Page 15TX RX Systems Inc. 10/29/04
and will remain in place when the screws are
removed.
2) Slide the amplifier towards the bottom of the
cabinet as far as it will go. This will allow the top
RF connector to clear the opening. Tilt the top
of the amplifier outwards and remove the top
RF cable at the SMA connector using the 5/16”
wrench. See
Figure 11
.
3) Slide the amplifier assembly towards the top of
the cabinet as far as it will go. This will allow the
bottom RF connector and grey control cable to
clear the opening. Tilt the bottom of the ampli-
fier outwards and remove the bottom RF cable
at the SMA connector and the grey control
cable. To remove the grey cable from the socket
on the amplifier it is necessary to squeeze the
top and bottom of the connector together to
release a hold down tab. When properly
squeezed the grey cable will disconnect easily
from the amplifier. Refer to
Figure 12
.
4) To replace the amplifier assembly repeat steps
1 through 3 in reverse order. When replacing
the RF cables do not overtighten the SMA con-
nectors. They should be tightened just slightly
more than hand tight or to the specification of 7
in/lbs. The replacement amplifier comes with an
attached gasket which must press up against
the outside of the cabinet firmly and squarely in
order to provide a correct moisture seal.
Module Replacement
The SB II modules are field replaceable. Follow the
steps listed below in sequential order. The required
tools are a #1 Phillips screwdriver. Two thumb
screws hold each module into place.
Note:
Power to the SB II cabinet must
be turned OFF during the module
replacement process except for the
amplifier modules which are “HOT”
switchable.
1) Loosen the two thumb screws which hold the
module into place. Phillips screws are incorpo-
rated into the thumbscrews and they made
need to be loosened first.
2) Grasping the two loosened thumb screws pull
the module straight out of the card cage.
3) To install the replacement module place the
module into the guide-rails of the slot and press
down firmly into place. Each type of module is
keyed uniquely to fit in only one slot within the
card cage. Once the card is seated into place
properly tighten the thumb screws.
The SB II low level and mid level amplifier stages
are field replaceable by simply removing the mod-
ule and plugging in a replacement. These modules
are HOT switchable meaning they can be swapped
without powering down the system. RF cables
attached to the modules must be removed (5/16”
wrench) prior to swapping the modules and must
be re-attached after the new module is in place.
when replacing the RF cables do not overtighten
the SMA connectors. They should be tightened just
slightly more than hand tight or to the specification
of 7 in/lbs.
Modules can be swapped between the uplink and
downlink branches for troubleshooting purposes. If
a problem exists in one branch and the problem
moves to the other branch when modules are
swapped around this indicates a defective module.
Note:
After an amplifier module is
replaced use the Calibrate Currents
software function to properly set the
amplifiers alarm trip point, see page 9.
Due to slight differences in component
tolerances the trip point must be reset for any new
amplifier assemblies introduced into the system.
NOTE
NOTE
Figure 12
: Slide amplifier towards top of cabinet to
remove lower cables.
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