SECTION 4. TROUBLESHOOTING
1. General
A. Troubleshooting is an orderly process of checking and eliminating possible causes of trouble until the
exact cause of a trouble is found. As a rule, the best place to start looking for the cause of a trouble in a
circuit is at the source of power. Continue testing and checking the circuit, step-by-step, in an orderly man-
ner, until the cause of trouble is located. See applicable connection diagrams and schematic diagrams.
Do not overlook the obvious. Loose connections are the primary cause of malfunctions, both internal and
external to the machine. Do not overlook bad grounds, wrong settings, or worn out contactors.
Test points are identified on schematic diagrams listed in Chapter 5. P.C. Board test points are identified
and test point values are given in Section 3-3, Figures 1 and 2. The minimum equipment needed to trou-
bleshoot this machine is a simple voltohmmeter. An oscilloscope is the best device to find and correct diffi-
cult problems.
B. This section provides information useful in diagnosing and correcting certain troubles which cause un-
satisfactory operation or failure of the equipment.
C. Minor troubles may be remedied by the operator; however, major repairs must be undertaken by expe-
rienced mechanics and electricians only. Replacement of SCR devices are to be performed at the factory
or an authorized service center.
2. Troubleshooting (See Figure 1)
A. Description The troubleshooting chart lists information under three headings:
(1) Trouble, symptom, and condition
(2) Probable cause
(3) Test, check, and remedy
B. Use of the Troubleshooting Chart
The troubleshooting chart is designed to provide maintenance and repair personnel with a time-saving
guide for locating the source of a trouble.
(1) Terminal points
(Ref. applicable schematic and connection diagrams),
installed on the power sup-
ply at several locations, provide easily accessible and identifiable test points for checking circuits and
electrical components.
(2) Test points are located throughout the circuitry in such a manner that input and output power may
be used for test purposes. Because of these test points and their location, a complete check of cir-
cuitry may be completed very quickly. Therefore, “probable causes” and “remedies” are listed in a
step-by-step sequence which will insure power for testing in all instances where input or output power
may be used with proper safety practices, test equipment, and training experience.
(3) Printed circuit board output troubles should be pinpointed only to determine if the problem is a
board calibration problem or a PC board failure problem. Failure of PC board requires replacement of
the board. Field repair attempts are not recommended. See 3-3 for calibration instructions.
OM-2010
April 10/89 Revised 3-4
Page 1
To Next Page
Loading...
