Racal Instruments 3162A/B, User Manual

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User Manual 3162A/B
Maintenance and Performance Checks 5-3
Repair and
Replacement
Repair and replacement of electrical and mechanical parts must be
accomplished with great care. Printed circuit boards can become warped,
cracked or burnt from excessive heat or mechanical stress. The following repair
techniques are suggested to avoid inadvertent destruction or degradation of
parts and assemblies:
1. Use a 60/40 solder and temperature-controlled 35 - 40 watt pencil-type
soldering iron on the circuit board. 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 circuit from the base material.
2. Keep the soldering iron in contact with the PC board for a minimum time to
avoid damage to the components or printed conductors.
3. To desolder components, use a commercial "solder sucker" or a solder-
removing SOLDER - WICK, size 3.
4. Always replace a component with an exact duplicate as specified in the
parts list.
Performance
Checks
The following performance checks verify proper operation of the instrument and
should normally be used:
1. As a part of the incoming inspection of the instrument specifications;
2. As part of the troubleshooting procedure;
3. After any repair or adjustment before returning the instrument to regular
service.
Environmental
Conditions
Tests should be performed under laboratory conditions having an ambient
temperature of 25
°
C,
±
5
°
C and at relative humidity of less than 80%. If the
instrument has been subjected to conditions outside these ranges, allow at
least one additional hour for the instrument to stabilize before beginning the
adjustment procedure. Always perform a self-test sequence before
commencing with the performance checks. The self-test, if executed without
any failure, ensures proper operation of the generator. If self-test failures have
been encountered, the instrument first must be serviced and the source of
failure removed. Instructions on how to perform self-test are given later in this
chapter in the
Self-Test section.
Warm-up Period
Most equipment is subject to a small amount of drift when it is first turned on.
To ensure accuracy, turn on the power to the Model 3162A/B and allow it to
warm-up for at least 30 minutes before beginning the performance test
procedure.