Power Supply and Lamp Circuit.

TM 55-4920-411-13&P

4-8.

Power Supply and Lamp Circuit.

and reconnect to pin H. VOM should show continuity

when S3 switch is placed to high oil temp. If not, see fig

a. Using a volt-ohm-milliammeter, determine that pin

4-5 to isolate the problem.

A of receptacle J 1 and pins F and C of receptacle J2 are

connected to the signal unit case.

e. Using a 28 vdc power supply, apply 23 vdc to the

J2 terminals listed in table 4-6. Corresponding lamps

b. Using a VOM, measure the resistance between

should light. If not, see figs 4-1 and 4-5.

pins A and B of receptacle J2. Resistance should be less

than 1.5K ohms. (See Troubleshooting Table 4-3 and fig

f. Turn POWER switch off and connect power cable

4-5.)

to POWER receptacle and to a single-phase source of

115 Vac, 50-400 Hz (fig 4-11).

c. Using a VOM, check the test cable for continuity

and shorts.

g. Turn POWER switch on. Power lamp should light

and SECONDS timer should read 00. If not, see Trouble-

d. Connect a VOM between pins J and G of receptacle

shooting Table 4-3, steps h, i and j and fig 4-1 to isolate

J2. VOM should show continuity when S3 switch is

the problem.

placed to low oil pressure. Disconnect lead from pin G

Table 4-6. Lamp Circuit Test Table

J2 TERMINAL

LAMP

+28 VDC

Hi Oil Temp.

Low Oil Press.

4-17