7-2 Maintenance – EP350 (Limited Keypad Model): Safe Handling of CMOS and LDMOS Devices
Cleaning External Plastic Surfaces
Apply the 0.5% detergent-water solution sparingly with a stiff, non-metallic, short-bristled brush to
work all loose dirt away from the radio. Use a soft, absorbent, lintless cloth or tissue to remove the
solution and dry the radio. Make sure that no water remains entrapped near the connectors, cracks, or
crevices.
Cleaning Internal Circuit Boards and Components
Isopropyl alcohol (100%) may be applied 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. After completing 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.
7.3 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.
Note:
Always use a fresh supply of alcohol and a clean container to prevent contamination by
dissolved material (from previous usage).
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