Directed Electronics 554A Instrukcje Operacyjne Pobierz pdf (Strona 33)

c. Additional Equipment. The additional equipment

required to perform the quarterly test procedure is

Oscilloscope AN/USM-281(*).

d. Oscilloscope 7ime Differential (Delay) Measure-

ment Procedure. To provide the greatest accuracy

when measuring delays, certain steps of the quarterly

test procedures (table 4-1) delays shall be measured as

follows:

(1) With oscilloscope sweep display switch set to

MAIN, adjust DIV DELAY control to position inten-

sified trace (reduce INTENSITY setting as necessary

to view) over first point of interest on waveform.

(2) Set sweep display switch to DELAYED.

(3) Readjust DIV DELAY control to position point

of interest on waveform exactly on a vertical reference

line (normally center vertical line of graticule).

(4) Record setting of DIV DELAY control.

(5) Set sweep display switch to MAIN.

(6) Adjust DIV DELAY control to position inten-

sified trace over second point of interest on waveform.

TM 11-6625-2611-12

(7) Set sweep display switch to DELAYED.

(8) Readjust DIV DELAY control to position sec-

ond point of interest on waveform exactly on vertical

reference line (same reference line used in (3) above).

(9) Record setting of DIV DELAY control.

(10) Calculate difference between setting

recorded in (4) above and setting recorded in (9) above.

(11) Multiply MAIN TIME/DIV switch setting by

difference obtained in (10) above to obtain delay be-

tween two points of interest on waveform.

4-10. General Troubleshooting Information

The troubleshooting chart (para 4-11) lists symptoms

that may be observed while performing the operator’s

preventive maintenance checks. If a malfunction oc-

curs, perform the corrective actions indicated. Any

malfunction that is beyond the scope of the operator to

correct shall be referred to a higher category of mainte-

nance.

Table 4-1. Quarterly Test Procedure

Control Settings

Oscilloscope

Set up oscilloscope as

described in para-

graph 2-11c

DISPLAY switch B

B VOLTS/DIV 1.

MAIN TIME/DIV DIV

2 µ sec.

DELAYED TIME/DIV

switch 0.1

sec

Sweep display switch

DELAYED

DELAYED TIME/DIV

switch 0.2

sec

DELAYED TIME/DIV

Test set

[

Test procedure

Power Supply Test

Set up test set as de-

scribed in paragraph

2-11d

Check POWER indicator

Check POWER DC FAULT indica-

tor.

Press POWER DC FAULT indicator.

PRF Generator PRF Measuring Section Test

PRF SELECT RANGE

switch X100 -

MEASUREMENT PRF

RANGE switch X1OO

PRF SELECT RANGE

switch X10

MEASUREMENT PRF

RANGE switch X1O

PRF SELECT switch to

1/2

MEASUREMENT PRF

RANGE switch X1K

PRF SELECT RANGE

switch X1K

PRF SELECT switch X1

Adjust PRF SELECT MULT control

until meter indicates 9.0 on Hz

scale.

Adjust PRF SELECT MULT control

until meter indicates 10.0 on Hz

scale.

Adjust PRF SELECT MULT control

until meter indicates 10.0 on Hz

scale.

observe MEASUREMENT meter.

Timing

Marker Test

Observe three sets of markers. Each

set will be of different amplitude

and spacing.

Using time differential measure-

ment procedure described in para

4-9d. Measure spacing between

leading edge of the first lower

amplitude set of pulses.

Observe second set of pulses.

(Amplitude level more than pre-

vious pulses but less than the third

set of pulses.)

Observe third set of pulses with first

Performance standard

POWER indicator illuminates.

POWER DC FAULT indicator is ex-

tinguished.

POWER

FAULT indicator illumi-

nates.

PRF SELECT RANGE and MULT con-

trols indicate prf is 8, 100 to 9,900

Hz.

PRF SELECT RANGE and MULT con-

trols indicate prf is 900 to 1100 Hz.

PRF SELECT RANGE and MULT con-

trols indicate prf is 81 to 110 Hz.

Meter indicates 4.5 to 5.5 on Hz scaIe.

Three sets of markers are present.

Pulses are spaced 0.1 µ sec ±0.02%,

>0.5 volts amplitude.

pulses are spaced 1.0

sec ±0.02%,

>o.5 volt amplitude.

Pulses am spaced 10.0 µ sec ±0.02% ,

4-5

1 2 ... 28 29 30 31 32 33 34 35 36 37 38 ... 58 59

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