Component Removal And Replacement - Tektronix CURVE-TRACER 576 Instruction Manual

Maintenance-Type 576
tured for Tektronix, Inc. in accordance with our specifica-
tions. Each special part is indicated in the electrical parts
list by an asterisk preceding the part number. Most of the
mechanical parts used in this instrument have been manu-
factured by Tektronix, Inc. Order all special parts directly
from your local Tektronix Field Office or representative.
Ordering Parts. When ordering replacement parts from
Tektronix, Inc., include the following information.
1. Instrument Type.
2. Instrument Serial Number.
3. A description of the part (if electrical, include circuit
number).
4. Tektronix Part Number.
Soldering Techniques
WARNING
Disconnect the instrument from the power source
before soldering.
Circuit Boards. Use ordinary 60/40 solder and a 35- to
40-watt pencil type soldering iron on the circuit boards.
The tip of the iron should be clean and properly tinned for
best heat transfer to the solder joint. A higher wattage
soldering iron may separate the wiring from the base
material.
The following techniques should be used to replace a
component on a circuit board. Most components can be
replaced without removing the boards from the instrument.
1. Grip the component lead with long-nose pi iers.
Touch the soldering iron to the lead at the solder connec-
tion. Do not lay the iron directly on the board, as it may
damage the board.
2. When the solder begins to melt, pull the lead out
gently. This should leave a clean hole in the board. If not,
the hole can be cleaned by reheating the solder and placing
a sharp object such as a toothpick into the hole to clean it
out. A vacuum-type desoldering tool can also be used for
this purpose.
3. Bend the leads of the new component to fit the holes
in the board. If the component is replaced while the board
is mounted in the instrument, cut the leads so they will just
protrude through the board. Insert the leads into the holes
in the board so the component is firmly seated against the
board (or as positioned originally). If it does not seat pro-
perly, heat the solder and gently press the component into
place.
4. Touch the iron to the connection and apply a small
amount of solder to make a firm solder joint. To protect
heat-sensitive components, hold the lead between the com-
ponent body and the solder joint with a pair of long-nose
pliers or other heat sink.
5. Clip off the excess lead that protrudes through the
board (if not clipped in step 3).
4-10
6. Clean the area around the solder connection with a
flux-remover solvent. Be carefu I not to remove information
printed on the board.
Ceramic Terminal Strips. Solder used on the ceramic
terminal strips should contain about 3% silver. Use a 40- to
75-watt soldering iron with a 1 /8-inch wide wedge-shaped
tip. Ordinary solder can be used occasionally without dam-
age to the ceramic terminal strips. However, if ordinary
solder is used repeatedly or if excessive heat is applied, the
solder-to-ceramic bond may be broken.
A sample roll of solder containing about 3% silver is
mounted on the right side of the instrument below the
bracket holding the VERT OUTPUT GAIN and HORIZ
OUTPUT GAIN adjustments. Additional solder of the same
type should be available locally, or it can be purchased
from Tektronix, Inc. in one-pound rolls order by Tek-
tronix Part No. 251-0514-00.
Observe the following precautions when soldering to a
ceramic term ina I strip:
1. Use a hot iron for a short time. Apply only enough
heat to make the solder flow freely.
2. Maintain a clean, properly tinned tip.
3. Avoid putting pressure on the ceramic terminal strip.
4. Do not attempt to fill the terminal-strip notch with
solder; use only enough solder to cover the wires adequate-
ly.
5. Clean the flux from the terminal strip with a flux-
remover solvent.
Metal Terminals. When soldering to metal term ianls
(e.g., switch terminals, potentiometers, etc.), ordinary
60/40 solder can be used. Use a soldering iron with a 40- to
75-watt rating and a 1 /8-inch wide wedge-shaped tip.
Observe the following precautions when soldering to a
metal terminal:
1. Apply only enough heat to make the solder flow
freely.
2. Apply only enough solder to form a solid connection.
Excess solder may impair the function of the part.
3. If a wire extends beyond the solder joint, clip off the
excess.
4. Clean the flux from the solder joint with a flux-
remover solvent.
Component Removal and Replacement
WARNING
Disconnect the instrument from the power source
before replacing components.
Not all the components in this instrument are accessible
without first removing some obstructions, such as circuit
boards, CRT and shield or the guard box. None of these
obstructions, however, are difficult to remove or replace.
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