Chapter 1 Introduction
1.1 General
This manual includes all the information needed to maintain peak product performance and
maximum working time for the ASTRO APX 2000/ APX 4000/ APX 4000Li/ APX 1000 (900 MHz)
radio. This detailed level of service (component level) is typical of the service performed by some
service centers, self-maintained customers, and distributors.
Use this manual in conjunction with the APX 2000/ APX 4000/ APX 1000 (900 MHz) VHF
(136–174 MHz), UHF1 (380–470 MHz), UHF2 (450–520 MHz), 700/800 MHz (764–870 MHz) and
900 MHz (896–941 MHz) Digital Portable Radios Basic Service Manual (Motorola part number
68012004056), which can help in troubleshooting a problem to a particular printed circuit (PC) board.
Conduct the basic performance checks outlined in the basic service manual first to verify the need to
analyze the radio and to help pinpoint the functional problem area. In addition, you will become
familiar with the radio test mode of operation, which is a helpful tool. If any basic receive or transmit
parameters fail to be met, the radio should be aligned according to the radio alignment procedure.
Included in other areas of this manual are functional block diagrams, detailed theory of operation,
troubleshooting charts and waveforms, schematics, and parts lists. You should become familiar with
these sections to aid in determining circuit problems. Also included are component location diagrams
to aid in locating individual circuit components and some IC diagrams, which identify some
convenient probe points.
“Chapter 3, Theory of Operation,” on page 3-1, contains detailed descriptions of the operations of
many circuits. Once you locate the problem area, review the troubleshooting flowchart for that circuit
to fix the problem.
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