1.1 YOUR "UNIT MAINTENANCE HANDBOOK"
PURPOSE. Your "Unit Level Maintenance Handbook," TM 11-5820-890-20-3 (Short
Title: TM 20-3), is designed for you, the unit level SINCGARS maintainer, to use in the
field, inside combat vehicles, and in all kinds of weather. This handbook assumes that
you are a trained SINCGARS maintainer and have ready access to TM
11-5820-890-20-1 and TM 11-5820-890-20-2 (Short Titles TM 20-1 and TM 20-2), "Unit
Maintenance Manual," which contain detailed maintenance instructions. Your
logbook size handbook contains abbreviated troubleshooting procedures, which
when properly applied will provide the same results as the procedures contained in
TM 20-1. Your handbook also offers selected technical data which you may use as
guides or memory joggers. The basic purpose of this manual is to provide you
essential job information that you can carry with you in the field. It is expected that
you will refer to TM 20-1 and TM 20-2 whenever more detailed information is required.
BASIS OF ISSUE. This logbook size handbook is issued on the basis of one per unit
level SINCGARS maintainer. You are encouraged to treat this guide as "personal
property," adding notes and making changes as your experience warrants. It is
intended that this manual be taken with you whenever you are required to work on
SINCGARS radios in the field.
LOCATING SUBJECTS. Several features of this handbook make it easy for the unit
maintainer to find desired material. There is a complete Table of Contents at the front
of the manual, a detailed Subject Index at the rear. Also, Sections IV and V have
Tables of Contents at the front of each section.
GOAL. The goal is to provide the unit maintainer adequate guidance to be able to
troubleshoot, properly identify, and correct most problems encountered in the field for
both manpack and vehicular radios. It does not replace or preclude the need to use
TMs 20-1 and 20-2 when more specific, in-depth guidance is required for job
HOW TO USE YOUR UNIT MAINTENANCE HANDBOOK. Use of TM 20-3 is
illustrated in this example. A unit maintainer is called to a combat vehicle that has a
radio problem. By questioning the radio operator, the maintainer determines the
general nature of the problem. The unit maintainer then performs the appropriate
Operational Check found in the Handbook, performing each step in the manner and
the order prescribed. This procedure will take the maintainer to the point where the
faulty component is identified, or the maintainer is referred to one or more specific
troubleshooting guide to use. Once the faulty component has been identified and
either replaced or repaired, the maintainer again performs the Operational Check to
ensure that the entire system is in fact operational. Handbook chapters entitled Cable
Schematics and Selected Graphics provide additional information which may be of
use to the maintainer during the troubleshooting and replacement/repair effort. When
the problem can be isolated to components other than the radio system (e.g. VIC-1,
Control-Monitor, RCU, Single Radio Mount), the maintainer must use TM 20-2 rather
than the handbook to continue troubleshooting.