TM 11-5805-424-15/NAVSHIPS 0967-220-9010/TO 31W2-2G-41
6-4. Localizing Troubles
b. Use of Troubleshooting Chart.
The
a. General. The following procedures are to be
troubleshooting chart (b below) is used by checking the
used to localize troubles when abnormal indications are
obtained during the operational tests (para 6-3), or when
Symptom column for abnormal operation. The Probable
Symptoms of abnormal operation are indicated by
trouble column characterises the nature of the trouble.
operating or organizational maintenance personnel.
The Corrective measure column indicates the circuits or
Certain results obtained during this procedure localize
circuit elements to be checked, or references a
the trouble to a particular component. However, in
troubleshooting procedure when further troubleshooting
general, the procedure localizes the trouble to a specific
steps are necessary.
logic circuit or to a small group of logic circuits.
The trouble is then localized to a component or
Note. The probable trouble and corrective
connection by use of the isolation procedures (paras 6-
measures indicated below do not Include the possibility
of defective wiring.
When the trouble cannot be
the printed-circuit board layout diagrams (figs. 6-2
repaired using the corrective measures Indicated, check
through 6-26), component location illustrations (figs 6-27
the wiring associated with the particular circuit and
through 6-30), the schematic diagrams (figs. 8-6 through
repair any defective wiring.
and fig. 8-28).
c. Troubleshooting Chart.
Item
Symptom
Probable trouble
Corrective measure
No.
1
AC POWER indicator lamp
a. Check for input ac voltage at output
does not light with AC
terminals of line filter; replace
POWER switch at ON.
filter, if defective (par 6-8).
b. Defective AC POWER switch S1
b. Check for as voltage across pins 1
(fig. 8-28).
and 4 of transformer TI (fig.
is not present (para 6-8a).
c. Defective power transformer T1
pins 9 and 10 and 9 and 11 of
transformer T1 (fig. 6-42); replace
transformer, if defective.
d. Defective feedthrough capacitors
2A1C10, 2A1C111, 1A1C3, 1A1C6,
replace defective part (para
or resistor 1A1R5 (fig. 6-28);
6-8a).
defective fuse holder.
2
MD-674(P)/G is completely
a. Defective filter capacitor C1 or C2
a. Check capacitors (fig. 6-42); replace,
inoperative, AC POWER
if defective (par 6-8a).
Indicator lamp lights.
b. Defective feedthrough capacitor
b. Check capacitors; replace defective
1A1C7 or 1A1C10 (fig. 6-29).
component (para 6-8a).
c. Defective power transistor or recti-
fiers on the power supply sub-
urements of power supply sub
module (fig. 6-28).
module components (fig. 6-18);
replace defective components
(par 6-8b).
3
Blower does not operate ------------
Defective fan motor BI (fig. 6-18) --------------
Replace fan assembly (para 6-8b).
4
No transmit data supplied by
a. Defective INPUT SELECT switch
MD-674(P)/G.
replace switch if defective (para
6-8a).
b. Defective output transformer T2
resistances (fig. 6-42); replace
transformer, if defective.
c. Shorted ORDER WIRE SEND
c. Check jack; replace, if defective (fig.
jack J1 (fig. 3-1).
8-28).
6-43
