Tektronix 5441 Instruction Manual page 94

C A U T I O N
a
Most circuit boards in this instrument are multi-layer
type boards with a conductive path@) laminated be-
tween the top and bottom board layers. All soldering
on these boards should be done with extreme care to
prevent breaking the connections to the center con-
ductor(~); only experienced maintenance personnel
should attempt repair of these boards.
For metal terminals (e.g., switch terminals, potentiome-
ters, etc.), a higher wattage-rating soldering iron may be
required. Match the soldering iron to the work being done.
For example, if the component is connected to the chassis
or other large heat-radiating surface, it will require a 75 W or
larger soldering iron.
mounted in the instrument, cut the leads so they will just
protrude through the board. Insert the leads into the holes
so the component is firmly seated against the board (or as
positioned originally). If it does not seat properly, 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 any excess lead protruding thrugh the board (if
not clipped in step 3).
6. Clean the area around the solder connection with a
flux-removing solvent. Be careful not to remove information
The following techniques should be used to replace a
printed on the board.
component on a circuit board.
1. Grip the component lead with long-nose pliers. Touch
the soldering iron to the lead at the solder connection. Do
not lay the iron directly on the board, as it may damage the
board.
COMPONENT REMOVAL AND
REPLACEMENT
I
W A R N I N G
)
2. When the solder begins to melt, gently pull the lead
out. If unable to pull out the lead without using force, try
removing the other end of the component, as it may be more
easily removed.
NOTE
The reason some component leads are troublesome
to remove is due to a bend placed on each lead during
the manufacturing process. The bent leads hold com-
ponents in place during a process that solders many
components at one time.
If a component lead is extremely difficult to remove, it
To avoid electrical shock, disconnect the instrument
from the power source before replacing components.
The exploded-view drawing associated with the Replace-
able Mechanical Parts list may be helpful in the removal or
disassembly of individual components or subassemblies.
Component locations are shown in the Diagrams and Circuit
Board Illustrations section.
Circuit Boards
If a circuit board is damaged beyond repair, replace the
entire board assembly. Part numbers for completely wired
boards are given in the Replaceable Electrical Parts list.
may be helpful to straighten the leads on the back side of
the board with a small screwdriver or pliers while heating the
To remove or replace a board, proceed as follows.
soldered connection.
1. Disconnect all leads connected to the board (both sol-
dered lead connections and solderless pin connections).
Use only enough heat to remove the component lead
without removing the solder from the board. If it is desired to
remove solder from a circuit-board hole for easier installa-
2. Remove all screws holding the board to the chassis or
tion of a new component, a solder-removing wick should be other mounting surface. Some boards may be held fast on
used. one side by a slotted plastic bar in addition to the screws;
for these, remove the screws, then pull the circuit board
from its slot to free the board. Also, remove any obstruc-
3. Bend the leads of the new component to fit the holes tions that would prevent the board from being lifted out of
in the board. If the component is replaced while the board is the instrument.
REV MAY 1982