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 TM 55-1905-219-14-11
5-117. SHIP' COURSE INDICATOR - MAINTENANCE INSTRUCTION (Continued).
S
LOCATION
ITEM
ACTION
REMARKS
OVERHAUL-TEST
between the measured and tabulated voltages greater than ten percent indicates possible trouble as outlined in the table.
In general, no voltage indicates an open circuit between the test points and the power source; a low voltage indicates an
open circuit between the test points and the power source; a low voltage indicates an excessive load, such as a short
circuit, further along in the circuits. Repair any fault located by these tests.
(3) If the transistor stage appears at fault, energize the amplifier and, with a d-c voltmeter with a sensitivity of at
least 1000 ohms per volt, check measured voltages against normal voltages. Less than a ten-percent difference
between measured and tabulated voltages indicates satisfactory DC circuit conditions; a greater difference indicates a
possible cause of trouble.
d. Replacement of semiconductor device.
(1) If the fault appears to lie in a diode or transistor, or a component connected to a semiconductor device,
observe the following precautions.
(2) All small electronic components are limited in their ability to withstand the temperature necessary for a
properly soldered joint. Semiconductor components are especially susceptible to damage from high temperature.
(3) For this reason protect a diode or transistor from heat by firmly grasping the lead midway between
component and soldered joint with a pair of pliers. The nibs of the pliers must be free from dirt, grease, and other
coatings that would interfere with the rapid flow of heat into the pliers. Use the largest pliers that will fit. The pliers serve
as a heat sink to protect the semiconductor device. Continue to grasp the lead with the pliers throughout the soldering
operation and until the joint has cooled afterward.
(4) Use as small a soldering iron as will satisfactorily heat the junction to the melting point of solder; keep the tip
brightly tinned. Clean a terminal or eyelet of excess solder from a previous connection before starting to connect a
replacement part to it. Use only rosin-core solder and apply only enough solder to wet the joint.
5-1334
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