12/20/11 888-2595-001 5-31
WARNING: Disconnect primary power prior to servicing.
Section 5 Maintenance and Alignments
ZX Series
Figure 5-3 Removal of PA amplifier assembly from heatsink
If a module has failed with a persistent PA overcurrent fault, there may be uncertainty
as to which half of the module has actually failed. This uncertainty can be resolved by
removing both PA amplifier covers and looking for obvious cracking, burning of one or
both power MOSFETs, or the general presence of a burned smell.
Tools Required:
#1 star (Phillips) screwdriver
7/64 hex key
Thermal compound Wakefield 120-8 or equivalent (404-0899-077) thermal pad
Rubber roller, razor blade, or straight-edge
STEP 1 Obtain replacement power amplifier assembly. Replacement PA board
will include thick copper plate under PC board. Do not remove PC
board from copper plate.
STEP 2 Remove cover of damaged power amplifier assembly.
STEP 3 Remove (only) larger countersunk screws to free copper plate from
larger aluminum heatsink.
[005]
[004]
[003]
[002]
[001]
[001] Thumbscrew
[002] Amplifier cover
[003] Power amplifier assembly
[004] Mating surface (apply
thermal pad or thermal
compound)
[005] Aluminum heatsink
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