TM 115826-22535
CHAPTER 3
REPAIRS AND ALIGNMENT
REPAIRS
Section 1.
e. When tightening the two setscrews in
31. General Parts Replacement Techniques
a collar-type clamp, the setscrews must be
The following general precautions should be
tightened against the center of the gear (or
observed when replacing parts in this equip-
other mechanical part) quarter. segments.
ment.
32. Removal and Replacement Techniques
a. When soldering or unsoldering transistor
leads or precision resistors, solder quickly to
The procedures for removing receiver sub-
allow as little heat conduction as possible.
assemblies and disassembling the receiver gear
Whenever wiring permits, use a heat sink
train subassembly are described in paragraph
(such as a long nose pliers) between the solder
3-3. The corresponding reassembly and re-
joint and the part. Use approximately the same
placement procedures are described in para-
length and dress of leads as used originally.
graph 3-4. Paragraph 3-4 also includes in-
structions for lubrication that is p e r f o r m e d
b. Use a pencil-type iron with a 25-watt
during receiver reassembly and replacement.
maximum capacity when working on replace-
The procedures for disassembling the control
ment of non pluck-out transistors. If the iron
must be used with ac, use an isolation trans-
sembly and lubrication that is performed dur-
former between the iron and the line. Check
ing reassembly of the control unit are de-
soldering irons for shorts to the iron tip be-
fore using. Do not use a soldering gun as dam-
cannot be disassembled and disassembly of the
aging voltages can be induced in components.
inverter and receiver mount are obvious,
c. In s o m e c a s e s p o w e r t r a n s i s t o r s a r e
mounted on heat sinks. When replacing power
33. Disassembly of Receiver
transistors, always replace the insulating
a.
Removal of Dust cover.
washer between the transistors and the heat
Loosen two screws (fig. 21) at front
(1)
sink if an insulator is used. Before installing
of the receiver and one screw at rear.
the mica or fiber washers, treat them with a
(2) Pull off dust cover.
film of silicone fluid or equivalent to help in
b. Removal of Power Supply and Servo
the transfer of heat. After the transistor is
mounted and before making connections, check
Compartment.
Remove four screws (A, fig. 3-1).
from transistor case to ground for effective
(1)
insulation.
(2) Swing out power supply and servo
compartment.
d. Whenever an electrical part such as a
(3) Remove four screws (A, fig. 3-2), and
resistor, capacitor, or a coil is to be removed,
remove the compartment.
note the exact position of the part before re-
moving it. Replace the part in the same p{wi-
c. Removal of Switch Shaft.
tion.
31
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