Safe Handling Of Cmos And Ldmos; General Repair Procedures And Techniques; Parts Replacement And Substitution; Rigid Circuit Boards - Motorola CDM Series Service Manual

Chapter 1: 2-2
2.2.2 Cleaning Internal Circuit Boards and Components
The only factory-recommended liquid for cleaning the printed circuit boards and their components is
isopropyl alcohol (100% by volume). Apply Isopropyl alcohol with a stiff, non-metallic, short-bristled
brush to dislodge embedded or caked materials located in hard-to-reach areas. The brush stroke
should direct the dislodged material out and away from the inside of the radio. Make sure that
controls or tunable components are not soaked with alcohol. Do not use high-pressure air to hasten
the drying process since this could cause the liquid to collect in unwanted places. Upon completion
of the cleaning process, use a soft, absorbent, lintless cloth to dry the area. Do not brush or apply
any isopropyl alcohol to the frame, front cover, or back cover.
NOTE Always use a fresh supply of alcohol and a clean container to prevent contamination by
dissolved material (from previous usage).
3.0

Safe Handling of CMOS and LDMOS

Complementary metal-oxide semiconductor (CMOS) devices are used in this family of radios. CMOS
characteristics make them susceptible to damage by electrostatic or high voltage charges. Damage
can be latent, resulting in failures occurring weeks or months later. Therefore, take special
precautions to prevent device damage during disassembly, troubleshooting, and repair.
DO NOT attempt to disassemble the radio without first referring to the disassembly and
!
reassembly sections in the Basic Service Manual (Motorola Publication part number
6881091C62 [CDM Series models] or 6881092C71 [PRO Series models]).
C a u t i o n
Handling precautions are mandatory for CMOS circuits and are especially important in low humidity
conditions.
4.0

General Repair Procedures and Techniques

4.1

Parts Replacement and Substitution

When replacing damaged parts, use identical part replacements. If an identical replacement
component is not locally available, check the parts list for the proper Motorola part number and order
the component from the nearest Motorola parts center (see the Appendix at the back of this manual).
4.2

Rigid Circuit Boards

This family of radios uses bonded, multi-layer, printed circuit boards. Since the inner layers are not
accessible, some special considerations are required when soldering and desoldering components.
The through-plated holes may interconnect multiple layers of the printed circuit. Therefore, exercise
care to avoid pulling the plated circuit out of the hole.
When soldering near the 18-pin and 40-pin connectors:
avoid accidentally getting solder in the connector.
•
be careful not to form solder bridges between the connector pins.
•
closely examine your work for shorts due to solder bridges.
•
6881091C63-A
Safe Handling of CMOS and LDMOS