CHAPTER 5. DIRECT SUPPORT TESTING PROCEDURES

TM 11-6660-204-25

CHAPTER 5

DIRECT SUPPORT TESTING PROCEDURES

peak value equals 2.83 times the voltmeter value;

5-1. General

conversely, the voltmeter value equals 0.353 times

a. Scope. This chapter contains testing proce-

the peak-to-peak value.) When an oscilloscope is

dures to be used by direct support maintenance

not available, an electronic voltmeter may be sub-

personnel to determine whether repaired equip-

stituted if allowance is made for the difference in

ment is performing satisfactorily for return to

i n d i c a t i o n s (rms versus peak-to-peak) as de-

users.

scribed above.

b. Test and Procedures. Tests are limited to

c. Equipment Warmup and Connections.

those that can be performed with the tools, test

(1) Before taking any measurements, allow

equipments, and materials allocated to direct sup-

the equipment to warm up for at least 30 minutes

port maintenance. Tests and procedures are on

with the power switch at STAND BY.

charts preceded by a list of test equipment and

(2) Adjust the operating controls to permit

material required, and by instructions for setting

optimum operation of the equipment.

up and interconnecting the test equipment.

(3) With the signal and power cable assem-

c. Performances Standards. Performance stand-

bly (Special Purpose Cable Assembly W601), in-

ards are included in each chart to provide a direct

terconnect jack J101 on the recorder, Frequency

go-no-go basis on which the tester can reject or

Standard TS-65C/FMQ-1, and a convenient 60-

pass the repaired equipment.

Hz power outlet. When making the connections to

the frequency standard, the black lead is con-

nected to the ground (lower) terminal and the

5-2. Standard Test Conditions

white lead to the signal terminal.

a. Test Equipment. Test equipment ordinarily

(4) Room temperature and humidity condi-

consists of Frequency Standard TS-65C/FMQ-1

tions must be normal and reasonably constant.

(as a signal source), Oscilloscope AN/USM-140

(5) Line voltage and frequency must be nor-

(as an indicating device), and a stopwatch. Also

mal and constant (115 volts (approximately) and

used is a radiosonde unit having a regulated out-

60 Hz).

put to simulate specific temperature, humidity, and

pressure conditions for dynamically checking the

accuracy of the Radiosonde Recorder AN/

5-3. Chart Feed Test

TMQ-5(*) data print.

The chart feed test measures the number of graph

line spaces that the chart travels in 5 minutes.

b. Alternate Test Equipment. If Oscilloscope

A N / U S M - 1 4 0 is not available, any test scope

a. Test Equipment and Materials. A stopwatch

capable of accepting, without overloading, input

is required for this test.

voltages of 40 volts (root mean square) or higher

b. Test Connections and Conditions. No special

can be used. If the test scope has no vertical cali-

connections are required. The prime power source

brator, then it must be calibrated by a reasonably

should supply 110 to 125 volts at exactly 60 Hz as

accurate voltmeter and an adjustable source of

indicated on the control panel meters. Check the

60-Hz voltage. This calibration should be continu-

number of speeds in the following procedure as

ous between zero and 115 volts peak-to-peak, or 40

applicable to the unit being tested.

volts rms. (For sine wave shapes, the peak-to-

5-1