Section Il. TROUBLESHOOTING

TM 11-6130-385-34

Table 3-5. Test Equipment - Continued

Army

designation

Name

Part

number

Manufacturer

number

C o m m e r c i a l . . . . . . . . . . . . . .. Resistor, 52.9± 1% ohm, 250w (qty 6) . . . . . . . . . . . . . . . . .

C o m m e r c i a l . . . . . . . . . . . . . .. Resistor, 55.7± 1% ohm, 250w (qty 3) . . . . . . . . . . . . . . . . .

Commercial . . . . . . . . . . . . . . . Inductor, 32 ± 3% mh (qty 3) . . . . . . . . . . . . . . . . . . . . . . . . . .

................

C o m m e r c i a l . . . . . . . . . . . . . .. Capacitor, 2.3 ± 3% µ f, 150 vac (qty 3) .

Section Il. TROUBLESHOOTING

3-6.

General

b. C h e c k t h e u n i t w i t h c o v e r s i n t a c t p e r p a r a -

a. Troubleshooting of the static inverter shall be

graphs 3-41 through 3-51 before removing the

in accordance with tables 3-6 and 3-7 and the

covers and proceeding with the following proce-

w a v e f o r m s shown on figure FO-1. Troubleshooting

dures. After the unit has been examined and

will be performed with a variable 0 to +40 vdc

t e s t e d with covers on as noted, open and visually

power supply source and with a dc voltmeter and a

inspect it for burned or otherwise damaged

dc ammeter connected between the power supply

c o m p o n e n t s . Where failed components are located,

resistance and continuity checks should be per-

and connector J2 of the static inverter. For a

c o m p l e t e listing of test equipment, refer to table

formed to isolate the faulty circuits and to identify

the cause of the failure. It will be necessary to

3-5.

WARNING

remove protective coating from leads to take

M a k e sure all switches and circuit break-

readings. Where certain problems are apparent

e r s supplying power to the PP-7274/A are

during testing, proceed in accordance with table

i n the OFF position before connecting or

3-6.

d i s c o n n e c t i n g the input and output power

3-7.

Detail

Network

Troubleshooting

Loca-

cables from the unit or before starting

tion

any

maintenance procedure.

CAUTION

The following is an abstract of data in table 3-7 to

Although voltages in the static inverter

aid in locating the various detail troubleshooting

procedures.

a r e relatively low (e.g., ± 28 vdc and 115

vac), current levels are high (up to 41

Table

3-7

Sequence

No.

Network

amperes in normal operation, and much

1 ... . . . . .. . . . . . . ..5.1v regulator (A4)

. . . . . . . . . . . . . . . . ..2.5v regulator (A4)

higher in short circuit situations where

. . . . . . . . . . . . . . . . . . Excessive input current (A6) (A4)

the input capacitor bank can discharge

(A5)

through the short). As a result, failures

. . . . . . . . . . . . . . . . .. Hf oscillator (A1)

are often catastrophic; therefore, unless

. . . . . . . . . . . . . . . . . . 3Ø

sine

wave

generator

(A1)

t h e symptoms of a failure are known, be

. . . . . . . . . . . . . . . . ..8 vdc Regulator (A4)

. . . . . . . . . . . . . . . . .. Recovery Drive (A1) (A9)(A7)

extremely careful when troubleshooting

8 . . . . . . . . . . . . . . . . . . A0 feedback and control (typical)

the static inverter. Be sure to apply

(A2) (A5)

carefully monitored low voltages to the

. . . . . . . . . . . . . . . . . . Output

drive

(A4)

(A7)

(A4)

LOSS o f

unit to insure that no further damage will

regulation,

output,

high

distortion,

occur. Examine and test the outside

one or more phases

10 . . . . . . . . . . . . . . . . . . . P o w e r s w i t c h c i r c u i t s ( A 7 )

power supply source. Check to see that the

11 . . . . . . . . . . . . . . . . . . . Low or high output voltage (unit)

o u t s i d e power source will apply 0 to +31

distortion

and

regulation

within

voltages evenly as required.

specified

limits

Change 1

3-5