Tektronix 502A, Instruction Manual

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Maintenance—Type 502A
1. Use a soldering iron of about 75-watt rating.
2. Prepare the tip of the iron as shown in Fig. 4-1.
3. Tin only the first 1/16 to 1/8 inch of the tip. For
soldering to
ceramic terminal strips tin the iron with solder
containing about 3% silver.
Fig. 4-2. Correct method of applying heat in soldering to a ceramic
strip.
4. Apply one corner of the tip to the notch where you
wish to solder (see Fig. 4-2).
5. Apply only enough heat to make the solder flow
freely.
6. Do not attempt to fill the notch on the strip with
solder; instead, apply only enough solder to cover the
wires adequately, and to form a slight fillet on the wire as
shown in Fig. 4-3.
Fig. 4-3. A slight fillet of solder is formed around the wire when
heat is applied correctly.
In soldering to metal terminals (for example, pins on a
tube socket) a slightly different technique should be em­
ployed. Prepare the iron as outlined above, but tin with
ordinary tin-lead solder. Apply the iron to the part to
be soldered as shown in Fig. 4-4. Use only enough heat
to allow the solder to flow freely along the wire so that a
slight fillet will be formed.
Fig. 4-4. Soldering to a terminal. Note the slight fillet of solder-
exaggerated for clarity—formed around the wire.
General Soldering Considerations
When replacing wires in terminal slots clip the ends
neatly as close to the solder joint as possible. In clipping
the ends of wires take care the end removed does not
fly across the room as it is clipped.
Fig. 4-5. A soldering aid constructed from a 1/4 inch wooden
dowel.
Occasionally you will wish to hold a bare wire in place
as it is being soldered. A handy device for this purpose is
a short length of wooden dowel, with
ends shaped as
shown in Fig. 4-5. In soldering to terminal pins mounted
in plastic rods it is necessary to use some form of ' heat
sink'' to avoid melting the plastic. A pair of long-nosed
pliers (see Fig. 4-6) makes a convenient tool for this
purpose.
Ceramic Strips
To replace strips which mount with snap-in plastic fit­
tings, first remove the original fittings from the chassis.
Assemble the mounting posts on the ceramic strip. Insert the
nylon collar into the mounting holes in
the chassis. Carefully
force the mounting post into the nylon collars. Snip off the
portion of the mounting post which protrudes below the
nylon collar on the reverse side of the chassis.
4-2