TM 11-6625-1683-15
CHAPTER 7
REPAIRS AND ADJUSTMENT
Section I. REPAIRS
in paragraph 4-9g. Repair procedures are con-
7-1. General Parts Replacement Techniques
tained in TM 11-5840-298-35.
a. No unusual procedures are involved in the
replacement of parts in the MK980/PPS-5.
c. Internal Power Converter. Test procedures
The customary care must be observed in re-
for this unit appear in Chapter 6. The unit is
placing transistors or diodes. Avoid excessive
in a shield (fig. 75) on a pair of brackets
heat when soldering; use a 25-watt, pencil-
between the bottom of the test panel and a
type solder iron. If possible, use a heat sink or
partition. The interior of the shield may be
clamp a pair of long-nose pliers between a
reached by removing the four screws at the
solder joint and the diode or transistor. Do not
top corners and lifting off the cover plate (fig.
use soldering guns because of the danger of
inductive voltages being generated in compo-
service tests are possible. If service require-
nents. Make certain that the test panel, when
ments demand complete interior availability,
undergoing repair, is disconnected from the
remove the inverter circuit subassembly (fig.
powerline.
Q1 and Q2, diodes CR6 and CR6, filter choke
b. When replacing components, be careful to
L2, resistors R77, R78, and R79, and capacitor
avoid creating mechanical stresses or strains
C9. Remove the subassembly as follows:
that may cause ultimate, if not immediate,
(1) Remove the four machine screws that
breakdown. In general, the components and
secure it to the rear surface of the
structures in the MK-980/PPS-5 are easily
shield (fig. 7-4).
accessible. Thus, replacement of such items is
no problem, and standard techniques of de-
(2) Unsolder the nine leads connecting
mounting, remounting, and soldering are used.
terminals on the subassembly to ter-
minals of components mounted on the
7-2. Replacement of Parts
shield (fig. 7-5).
a. Receiver-Transmitter Power Converter
(3) Lift out the subassembly. All compo-
(PWR. CONV. RADAR) in Block 700. Test
nents comprising the internal power
procedures for this unit appear in Chapter 6.
converter assembly will now be ex-
If tests disclose a fault, remove and replace the
posed for test or replacement. If it is
unit in accordance with the procedures given
necessary to remove the complete in-
in paragraph 49f. Repair procedures are con-
ternal power converter, procede as
tained in TM 11-5840-298-35.
follows:
(a) Unsolder the three leads at the
Converter
b.
Control-Indicator Power
terminals of FL1, FL2, and FL3
(PWR. CONV. REMOTE) in Block 2300. Test
procedures for this unit appear in Chapter 6.
(b) Remove four screws securing the
If test disclose a fault, remove and replace the
converter side bracketa to the test
unit in accordance with the procedures given
7-1
AGO 7918A
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