TM 11-6625-1683-15
ment, voltage readings may be taken by use
may be the cause. Likewise, a fractured wire
of a multimeter, using any appropriate range.
or printed circuit board may be responsible.
Visual examination with the aid of magnifica-
tween patterns obtained at indicated test
tion may be of assistance in locating the
points. and reference patterns will materially
defect.
aid in the analysis of malfunction in those
i . Resistor, Capacitor, a n d Diode Color Code
circuits where waveform is of major signifi-
Diagrams. Color code diagrams for resistors,
cance.
capacitors, and diodes provide pertinent resis-
tance, voltage, rating, and tolerance informa-
g. Test Points. P a n e l - m o u n t e d t e s t j a c k s
tion (fig. 9-4 and 95).
connect to significant circuit points in each
block area of the equipment. Connection of
6-3. Test Equipment Required
testing instrumentation to these test points
will facilitate troubleshooting without need-
The following chart lists test equipment re-
less disassembly of the equipment. The sche-
quired for troubleshooting Test Facilities Kit
matic diagram (fig. 911) shows the circuit
MK-980/PPS-5.
The associated technical
location of each test point, and figure 910
manuals are also listed.
depicts their physical distribution and loca-
tion.
Test equipment
Technical manual
I
h. Intermittent Troubles. Trouble of an
Multimeter ME-26 B/U ------
TM 11-6625-200-12
intermittent nature is occasionally encountered,
Oscilloscope AN/USM-140B --
TM 11-6625 -535-15-1
I n e n d e a v o r i n g to
isolate
the
cause,
it
T e s t Set, Insulation Break-
TM 11-6625-273-12
down AN/GSM-6.
is generally necessary to induce the condi-
Tool Kit, Electronic Equip-
SB 11-604
tion by tapping, jarring, or probing the equip-
ment TK100/G.
ment. A cold-soldered or rosined connection
Section Il. TROUBLESHOOTING ELECTRICAL TEST PANEL SB-3004/PPS-5
Notes:
Circuit breaker
Block area
I
1. Short-circuit protection is afforded by circuit
breakers in the various power circuits. Failure of a
CONT-IND CB3 ----- At or dc operation. Block 2,300.
circuit breaker to remain in a closed condition is evi-
RCVR-XMTR CB4 --- Ac or dc operation. Blocks 700,
dence of either a short circuit or an excessive current
1,200, 500, 400, 2,100, 2,200.
demand in the associated circuit. If such a condition
develops, immediate investigation is required. Circuit
breaker protective response initiated by a malfunction
2. To a great extent, service analysis can be effected
in the test facilities kit must be divorced from the reac-
through the use of the panel-mounted test jacks and
tion induced by a shorted radar unit in the course of
connectors without removing the panel from its case.
service operations. To segregate externally caused cir-
However, some internal measurements may be required
cuit breaker reaction from an internally caused kickout,
or repairs necessitated, To gain access to the interior of
disconnect the interconnecting cable from the test facili-
the instrument, remove the 16 machine screws from
ties kit. If the trouble persists, corrective measures are
around the edge of the panel. Grasp the panel handles,
called for in the test facilities kit. The following chart
and gently lift the panel from the case. With the panel
indicates the block areas controlled by each circuit
removed from the case, interlock switch S28, which is
breaker:
secured to one of the rear side support bars, will auto-
matically open the input power circuits. Voltage tests
Block area
Circuit breaker
made at interior points will require that this interlock
switch be closed by manually pressing the actuating
MAIN PWR CB1 ____ A c operation only. Internal
button.
power converter.
CONTROL CB2 ----- A c or dc operation. Blocks
Caution: Several high-voltage points are
2 , 8 0 0 , 900, antenna drive
easily accessible with the rear of the panel
motor.
6-2
AGO 7918A
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