Motorola PRO2150, Руководство по обслуживанию, Страница: 16 / 22

August 30, 2002 99R85452E01-O
2-2 Maintenance : Safe Handling of CMOS and LDMOS Devices
NOTE: Always use a fresh supply of alcohol and a clean container to prevent contamination by
dissolved material (from previous usage).
2.3 Safe Handling of CMOS and LDMOS Devices
Complementary metal-oxide semiconductor (CMOS) devices are used in this family of radios, and
are susceptible to damage by electrostatic or high voltage charges. Damage can be latent, resulting
in failures occurring weeks or months later. Therefore, special precautions must be taken to prevent
device damage during disassembly, troubleshooting, and repair.
Handling precautions are mandatory for CMOS circuits and are especially important in low humidity
conditions. DO NOT attempt to disassemble the radio without first referring to the following
CAUTION statement.
2.4 Repair Procedures and Techniques — General
2.4.1 Parts Replacement and Substitution
When damaged parts are replaced, identical parts should be used. If the identical replacement part
is not locally available, check the parts list for the proper Motorola part number and order the part
from the nearest Motorola Communications parts center listed in the Piece Parts section of this
manual.
2.4.2 Rigid Circuit Boards
This radio uses bonded, multi-layer, printed circuit boards. Since the inner layers are not accessible,
some special considerations are required when soldering and unsoldering components. The printed-
through holes may interconnect multiple layers of the printed circuit. Therefore, exercise care to
avoid pulling the plated circuit out of the hole.
CAUTION: This radio contains static-sensitive devices. Do not open the radio unless you are
properly grounded. Take the following precautions when working on this unit:
• Store and transport all CMOS devices in conductive material so that all exposed leads
are shorted together. Do not insert CMOS devices into conventional plastic “snow”
trays used for storage and transportation of other semiconductor devices.
• Ground the working surface of the service bench to protect the CMOS device. We
recommend using the Motorola Static Protection Assembly (part number
0180386A82), which includes a wrist strap, two ground cords, a table mat, and a floor
mat.
• Wear a conductive wrist strap in series with a 100k resistor to ground. (Replacement
wrist straps that connect to the bench top covering are Motorola part number RSX-
4015.)
• Do not wear nylon clothing while handling CMOS devices.
• Do not insert or remove CMOS devices with power applied. Check all power supplies
used for testing CMOS devices to be certain that there are no voltage transients
present.
• When straightening CMOS pins, provide ground straps for the apparatus used.
• When soldering, use a grounded soldering iron.
• If at all possible, handle CMOS devices by the package and not by the leads. Prior to
touching the unit, touch an electrical ground to remove any static charge that you may
have accumulated. The package and substrate may be electrically common. If so, the
reaction of a discharge to the case would cause the same damage as touching the
leads.