Figure 41. Tube socket voltage and resistance diagram, main unit chassis, bottom view.

Figure 41. Tube socket voltage and resistance diagram, main unit chassis, bottom view.

nections to the minor components

Always be sure that the installation

o f the test set. Tap the suspected

i s satisfactory b e fore trouble-

parts gently with an insulated tool

shooting the test set.

such as a fiber rod. It impossible

(5) Signal substitution. The principal

t h a t the trouble is not in the test

advantage of the signal substitution

s e t itself, but in the installation

method (para 71 through 74) is that

(mountings, a c c e s s o r i e s , a d j u s t -

it usually enables the repairman to

ments, loose or damaged cables or

localize the trouble accurately and

c o n n e c t o r s , equipment undervest,

quickly to a particular stage when

etc). A detailed equipment per-

the preceding tests ((1) through (4)

formance checklist is given in TM

above) have not been successful.

1 1 - 6 6 2 5 - 3 5 1 - 1 2 . A careful check-

65. Test Equipment Required

o u t of the minor components, as

The following chart lists the test equip-

directed in the equipment perform-

a n c e checklist, will frequently in-

m e n t required for troubleshooting Radio

I n t e r f e r e n c e Measuring Set AN/URM-85,

dicate the cause of equipment

t h e associated technical manuals, and the

malfunction and will, perhaps,

e l i m i n a t e unnecessary and time-

assigned common names. Commercial

c o n s u m i n g troubleshooting within

test equipment is listed where Signal Corps

the individual subassemblies of the

t e s t equipment was not used for making

m a i n unit and the tuning units.

measurements.