Tektronix 184, Instruction Manual

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Maintenance-Type
1 84
The step-by-step technique is as follows:
1. Remove the component by cutting the leads near the
body. This frees the leads for ind ividual unsoldering.
2. Grip the lead with needle-nose pliers. Apply the
tinned tip of a 40-watt pencil soldering iron to the lead
between the pl iers and the board; then pul l gently.
3. When the solder first begins to melt, the lead will
come out, leaving a clean hole. If the hole is not clean,
use the soldering iron and
a
toothpick or a piece of enamel
wire to open the terminal hole. Do not attempt to drill
the solder out, since the through-hole plating might be
destroyed.
4. Clean the leads on the new component and bend
them to the correct shape. Carefully insert the leads into
the holes from which the defective component was re­
moved.
5. Apply the iron for a short time at each connection
on the side of the board opposite the component to prop­
erly seat the component.
6.
Apply the iron and a little solder to the connections
to finish the solder joint.
Ceramic terminal strips.
Solder used on the ceramic
terminal strips should contain about 3% si lver. Ordinary
tin-lead solder can be used occasionally without damage
to the ceramic terminal strips. Use a 40- to 75-watt sol­
dering iron with lis-inch wide chisel-shaped tip. If ordinar
y
solder is used repeatedly or if excessive heat is applied,
the solder-to-ceramic bond may be broken.
A small roll of 3% silver solder is mounted at the back
of the instrument. Silver-bearing solder can be purchased
directly from Tektronix in one-pound rolls; order by Tek­
tronix Part No. 251 -0514-00.
Observe the following precautions when soldering
ceramic terminal strips:
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 onl y enough solder to cover the wires ade­
quately.
5. Clean the flux from the term inal strip with a flux­
remover solvent to maintain good environmental charac­
teristics.
Metal terminals.
When soldering metal terminals (e.g.,
interconnecting plug pins, switch terminals, potentiometers,
etc.), ordinary 60/40 solder can be used. The soldering
iron should have a 40- to 75-watt rating with a lis-inch
wide chisel-shaped tip.
Observe the following precautions when soldering metal
terminals:
1 . Apply onl y 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.
4-2
3. If a wire extends beyond the solder joint, clip the
excess close to the joint.
4. Clean the flux from the solder joint with flux-remover
solvent to maintain good environmental characteristics.
Ceramic terminal strip replacement.
A complete
ceramic terminal strip assembly is shown in Fig. 4-l .
Replacement strips (including studs) and spacers are sup­
pl ied under separate part numbers. The old spacers may
be reused if they are not damaged.
Fig.
4-1 . Ceramic terminal strip assembly.
To replace a ceramic terminal strip, first unsolder all
connections. Then, the damaged strip can be pried or
pul led loose from the chassis. If the spacers come out with
the strip, remove them from the stud pins to be used for
installation of the new strip.
After the damaged strip has been removed, place the
undamaged spacers in the chassis holes. Then, carefully
press the studs into the spacers until completely seated.
If necessary, use a soft mallet to tap lightly, directly over
the stud area of the strip.
Switch Replacement
Individual wafers normally are not replaced in switch
assemblies. Replacement switches may be ordered from
Tektronix either unwired or with the associated wires and
components attached.
When soldering leads to a switch, do not let solder
flow around and beyond the terminal rivet as this may
destroy the contact spring tension.
Tubes and Transistors
Tubes and transistors should not be replaced unless
actually defective. However, temporary substitution is
often the fastest and best way to detect a defective tube
or transistor. Before substituting a tube or transistor, it is
suggested that circuit conditions be checked to be certain
that a replacement tube or transistor will not be subject
to damage. In some cases, these checks will also show
whether or not the tube or transistor is at fault.
®