(3) Control board assembly test fixture (fig. 4-
b. The following instruments or equivalents are
also required for general support troubleshooting:
(3) Electronic Counter AN/USM-207.
43. General Support Troubleshooting Procedures
(5) Strobotac, General Radio Model 1531.
The procedures prescribed for the lower categories of
4-2. Fabrication of Test Fixtures
maintenance are applicable at the general support level
of maintenance. Refer to chapter 3 of this volume and
a. The test fixtures listed below are not supplied
to TM 11-6720-242-12 for the data and procedures of
as components of the camera.
They must be
these levels. The troubleshooting charts of paragraph 4-
4 contain the symptoms, probable causes, and
b. Refer to the applicable figure and construct a
corrections of malfunctioning that could not be corrected
test set that permits a component board assembly to be
at the lower categories of maintenance. However,
plugged into a connector which is wired to the circuits
troubles may have been localized or isolated at the
and instruments shown in the illustration. An exception
lower levels but have not been corrected and in such
is a test setup for checking a motor and tachometer-
cases only the corrective measures are required at the
assembly, which requires direct power
general support level.
connections and provisions for the mechanical coupling
of a counter.
4-4. Troubleshooting Charts
The test fixtures to be fabricated are
illustrated in the figures designated.
Troubleshooting charts for the camera body, camera
(1) Interface board assembly test fixture (fig. 4-
control, control panel, and magazine are contained in
a. Troubleshooting Camera Body.
No IMC operation
a. Mode relay K3 on control board
a. Check IMC signal circuit (para
4-8f). Replace defective part.
a. Tachometer potentiometer R1,
a. Check and replace faulty part
resistors R2, R3.
.b. Replace tachometer-generator
Scan motor operation erratic
a. Worn carbon brushes
or not effective.
b. Brush retainer
c. Motor and gear assembly
Replace motor and gear assembly
Film advance improper
Scan drive gear train opera-
Worn or damaged gear
Examine each gear and replace where
any defect is evidenced. Lubricate
Focal plane plate
Replace (para 416).
a. Diaphragm blade
a. Examine both blades. Replace as
b. Pivot plate .
b. Replace if damaged (para 419
c. Defective pivot plate spring
d. Defective diaphragm blade guide
e. Shutter blade
f. Check blade spring and replace
Change 1 4-3