Figure 3-1. Initial Test Setup.

TM 11-6125-259-30

h. After completing voltage measurements, set

assembly (16); be careful of interconnecting wiring.

UNIT PWR switch S6 to down (off) position.

Install A7 assembly with six screws (20), six

Disconnect inverter from test fixture.

lockwashers (21) and six flat washers (22).

i If required at this time, carefully lay A7

j. Reassemble top and bottom covers (para 3-10

component assembly (17) back in place on top of A6

m and n), if required at this time.

Figure 3-1. Initial Test Setup.

3-2. Waveform Check of Component

down.

d. Carefully lay back upper end of A7 component

Assembly A6

assembly (17) 90 degrees over onto work bench.

The instructions in this paragraph are performed

Avoid strain on interconnecting wiring and be sure

only if internal inverter waveforms are required to

metal pins and connections do not touch inverter

be checked on component assembly A6.

case. A6 component assembly is now accessible. See

WARNING

figure 3-17 for location of reference pins.

High voltages and currents are present

e. Connect inverter to test fixture as shown in

on disassembled inverter when it is

figure-3-l.

energized. Do not touch any exposed

f. On test fixture, set load switches S2, S12 and

wiring or any metal point within the

S22 to up (83.3 VA) position. Set UNIT PWR switch

inverter: Lethal shock could result.

S6 to ON position and apply 281 vdc input power

a. Partially disassemble inverter (para 3-9 a). This

to inverter.

g. Connect Oscilloscope AN/USM-281

gains access to A7 component assembly (17).

(oscilloscope) and Counter AN/USM-207 (counter)

b. Loosen A7 component assembly (17) by

to pins 14(+) and 16(-) of component assembly A6.

removing six screws (20), six lockwashers (21) and

The observed waveform shall be as shown in figure

six flat Washers (22).

c. Place inverter on work bench with front side

3-2 and the counter shall indicate a frequency

3-2