Maintenance-Type 422 AC-DC
battery pack interconnecting terminals. If it is below about
22 volts, the battery pack has lost its charge retention
capacity. If the voltage is above about 22 volts, the low-
batteries indicator circuit may be at fault.
If the battery pack is found to be defective, the entire
battery pack should be returned to Tektronix, Inc. for
maintenance. Contact your local Tektronix Field Office or
representative for assistance. The battery pack should be
regarded as a single power storage unit rather than as a set
of individual cells. It is not designed to be disassembled for
inspection or repair. Refer all maintenance on the battery
pack itself to Tektronix, Inc.
CAUTION
The warranty on this instrument may be altered if the
sealed case-retaining screws of the battery pack are
removed.
CORRECTIVE MAINTENANCE
General
Corrective maintenance consists of component replace
ment and instrument repair. Special techniques required to
replace components in this instrument are given here.
Obtaining Replacement Parts
Standard Parts. All electrical and mechanical part
replacements for the Type 422 can be obtained through
your local Tektronix Field Office or representative. How
ever, many of the standard electronic components can be
obtained locally in less time than is required to order them
from Tektronix, Inc. Before purchasing or ordering replace
ment parts, check the parts lists for value, tolerance, rating
and description.
NOTE
When selecting replacement parts, it is important to
remember that the physical size and shape of a
component may affect its performance in the instru
ment, particularly at high frequencies. All replace
ment parts should be direct replacements unless it is
known that a different component will not adversely
affect instrument performance.
Special Parts. In addition to the standard electronic
components, some special components are used in the Type
422. These components are manufactured or selected by
Tektronix, Inc. to meet specific performance requirements,
or are manufactured for Tektronix, Inc. in accordance with
our specifications. These special components are indicated
in the Electrical Parts List by an asterisk preceding the part
number. Most of the mechanical parts used in this instru
ment have been manufactured 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:
I. 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 be
fore 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 technique 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 pliers.
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 firm ly seated against the
board (or as positioned originally). If it does not seat prop
erly, 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; do not apply
too much solder. To protect heat-sensitive components,
hold the lead between the component body and the solder
joint with a pair of long-nose pliers or other heat sink.
5. Clip the excess lead that protrudes through the board
(if not clipped in step 3).
6. Clean the area around the solder connection with a
flux-remover solvent. Be careful 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
El
4-9
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