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Section V
Paragraphs 5-18 to 5-22
Model 415E
b. If the meter tracking error is greater than±0.02
db, adjust A3R57 (See Figure 5-10) and repeat meas¬
urement until
meter tracking error is less than
±0.02 db.
5-18. REPAIR
AMD HiPUkCEMmi.
5-19. Certain procedures and precautions must be
followed when repairing or replacing any component of
the Model 415E.
Most of the amplifier and power
supply circuit components are located on the etched
circuit board. Instructions for working on the etched
circuit board are summarized in Paragraph 5-20.
Always disconnect the AC or battery power before re¬
placing or soldering any parts. Instruction for removal
and replacement of switches is detailed in Paragraph
5-27.
5-20. ITCHED €SS?€U!?S.
5-21. The etched circuit board in the SWR Meter is of
the plated-through type consisting of metallic con¬
ductors bonded to both sides of insulating material.
Soldering can be done from either side of the board with
equally good results. Table 5-3.lists required tools and
materials.
Following are recommendations and pre¬
cautions
pertinent to etched circuit repair work.
a. Avoid unnecessary component substitution: it can
result in damage to the circuit board and/or adjacent
components.
b. Do not use a high-power soldering iron on etched
circuit boards.
Excessive heat may lift a conductor
or damage the board.
c. Use a suction device (Table 5-3) or wooden tooth¬
pick to remove solder from component mounting holes.
DO NOT USE A SHARP METAL OBJECT SUCH AS AN
AWL OR TWIST DRILL FOR THIS PURPOSE. SHARP
OBJECTS MAY DAMAGE THE PLATED-THROUGH
CONDUCTOR.
d. After soldering, remove excess flux from the
soldered area and apply a protective coating to pre¬
vent contamination and corrosion. See Table 5-3 for
recommendations.
5-22. COMPONENT REPLACEMENT.
a. Remove defective component from circuit board.
b. Remove solder from mounting holes using a suc¬
tion desoldering aid (Table 5-3) or wooden toothpick.
c. Shape leads of replacement component to match
mounting hole spacing.
d.
Insert component leads into mounting holes and
position component as original was positioned.
DO
NOT FORCE LEADS OF REPLACEMENT COMPO¬
NENT INTO MOUNTING HOLES.
Sharp lead ends
may damage plated-through conductor.
Note: Axial lead components, such as resist¬
ors and tubular capacitors, can be replaced
without unsoldering. Clip leads near body of
defective component, remove component and
straighten leads left in board. Wrap leads of
replacement component one turn around orig¬
inal leads.
Solder wrapped connection, and
clip off excess lead.
Table 5-3.
Etched Circuit Soldering Equipment
Item
Use
Specification
Item Recommended
Soldering Tool
Soldering
Unsoldering
Wattage rating: 37.5
Tip Temp: 750 - 800°F
Tip Size:
1/8" OD
Ungar #776 Handle with
Ungar #1237 Heating Unit
Soldering Tip,
general purpose
Soldering
Unsoldering
Shape: chisel
Size: 1/8"
Ungar #PL113
De-soldering aid
Unsoldering multi-
connection components
(e. g., tube sockets
Suction device to remove
molten solder from
connection
Soldapullt by the Edsyn
Company, Arleta,
California
Resin (flux)
solvent
Remove excess flux
from soldered area
before application of
protective coating
Must not dissolve etched
circuit base board ma¬
terial or conductor
bonding agent
Freon
Acetone
Lacquer Thinner
Isopropyl Alcohol (100% dry)
Solder
Component replacement
Circuit board repair
Wiring
Resin (flux) core, high
tin content (60/40 tin/
lead), 18 gauge (SWG)
preferred
Protective
Coating
Contamination, corrosion
protection after soldering
Good electrical insula¬
tion, corrosion-
prevention properties
Krylon* #1302
Humiseal Protective Coating,
Type IB 12 by Columbia
Technical Corp. Woodside
77, New York
*Krylon Inc., Norristown, Pennsylvania
02152-3
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