Directed Electronics 554A Instrukcje Operacyjne Pobierz pdf (Strona 41)

TM 11-6625-2611-12

CHAPTER 5

ORGANIZATIONAL MAINTENANCE INSTRUCTIONS

5-1. General

Maintenance of the test set consists of cleaning the ex-

terior, replacing lamps and fuses, and minor cable

repair.

5-2. Cleaning

WARNING

The fumes of TRICHLOROETHANE are tox-

ic. Provide thorough ventilation whenever it is

used; avoid prolonged or repeated breathing

of vapor. Do not use near an open flame or hot

surface; trichloroethane is nonflammable but

heat converts the fumes to a highly toxic

phosgene gas the inhalation of which could

result in serious injury or death. Prolonged or

repeated skin contact with trichloroethane

can cause skin inflammation. When neces-

sary, use gloves, sleeves and aprons which the

solvent cannot penetrate.

CAUTION

Do not use trichloroethane on any painted or

silk-screened surface of the test set.

Clean the front panel and control knobs with a soft,

clean cloth. If dirt is difficult to remove, dampen the

cloth with water and use a mild soap. Clean exterior

metal surfaces as follows:

a. Remove moisture and loose dirt with a clean cloth

(item 2, app E).

b. Remove grease, fungus, and ground-in-dirt with

isopropyl alcohol (item 6, app E).

c. Clean unpainted surfaces with trichloroethane

(item 4, app E).

d. Remove dirt from hard-to-reach areas with a

brush (item 3, app E).

5-3. Touchup Painting Instructions

Remove rust and corrosion from metal surfaces by

lightly sanding with fine sandpaper (item 1, app E).

Brush two thin coats of paint on the bare metal to pro-

tect from further corrosion. Refer to applicable clean-

ing and refinishing practices specified in TB746-10.

5-4. Replacement of POWER Indicator

Lamp

Remove and replace the lamp as follows:

a. Unscrew indicator cap by turning it counterclock-

wise.

b. Press lamp in and turn it counterclockwise to

remove.

C. Install a replacement lamp (NE51H, NSN 6240-

00-683-3411 ) into lamp socket.

d. Tighten indicator cap by turning it clockwise.

5-5. Replacement of POWER DC FAULT in-

dicator Lamp

Remove and replace the lamp as follows:

a. Unscrew indicator cap by turning it counterclock-

wise.

b. Remove lamp from indicator cap.

c. Install replacement lamp (MS25237-327, NSN

6240-00-155-7836) into indicator cap.

d. Tighten indicator cap by turning it clockwise.

5-6. Replacement of Fuse

Remove and replace the fuse as follows:

a Unscrew fuse cap by turning it counterclockwise.

b. Pull defective fuse out of fuse cap and insert a

replacement fuse.

c. Reinstall replacement fuse (F02B250V1A, NSN

5920-00-284-9220) and fuse cap and tighten by turn-

ning clockwise.

5-7. Minor Repair of Cables

Repair minor cuts in cable insulation by covering it

first with insulation tape, and then with plastic tape. If

a cable is broken, ship defective cable to higher categw

ry of maintenance for repair.

5-8. CHAL AUX MOD DLY Knob Adjustment

If delay between main rf output and auxiliary output is

not 0.2

µ sec when control is set to detent, proceed as

follows:

a Connect test set and oscilloscope to 115 vac power

source.

b. Connect test set up as shown in figure 2-3 and set

oscilloscope controls as described in table 2-2 except as

follows:

A VOLTS/DIV

0.2

EXT 10/EXT/lNT/LINE

EXT

MAIN TIME/DIV

.1 µ SEC

C. Adjust test set controls as described in table 2-3

except as follows

MEASUREMENT FUNCTION PRF CHAL

SELECT switch

SCOPE TRIG/FREQ MEAS

Adjust to locate first challenge

DELAY (USEC) controls

pulse

d. Adjust SCOPE TRIG/FREQ MEAS DELAY

(USEC) MULT control to reference leading edge of

first pulse at center of Oscilloscope graticule.

e. Connect RF IN/OUT AUX jack to LOW PWR

MEAS IN jack.

f. Adjust CHAL AUX MOD DLY control to detent

position.

g. Loosen setscrews and hold knob so that ball

plunger remains seated in detent.

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