Service Manual

GSM-205-523
Replacing a Tx block, HCU or plate
31st Oct 01
Maintenance Information: Horizon macro indoor
68P02902W09-B
CONTROLLED INTRODUCTION
Maint. 2–25
Replacing a Tx block, HCU or plate
Introduction to
Tx block
replacement
WARNING Ensure that RF power is OFF, before disconnecting RF
cables. Severe burns may result if RF power is ON when
RF cables are disconnected.
CAUTION An earthing wrist strap must be worn when handling Tx
blocks. An ESP earthing connection point is provided
above the leftmost PSM.
There are three slots for Tx blocks in the top panel basket of a cabinet, above
the CTUs. There are four types of Tx block; DCF, TDF, DDF and HCU.
Replacing a Tx block requires removal of RF transmitter power for the CTU(s)
that connect with the faulty Tx block. It is therefore advisable to perform this
procedure during periods of low traffic. The OMC-R should be notified of
imminent repair activity.
If a stacking bracket is fitted, the CCB basket has to be removed in order to gain
access to the Tx block modules (see Replacing a CCB ).
It is important to ensure that all unused Tx Block M6 screw locations have a
screw in place and tightened to correct torque (see Overview of replacement
procedures). This is to ensure maximum quality of EMC and general
containment.