BENDIX ADF-T12B Maintenance Manual page 42

M A I N T E N A N C E P R A C T I C E S
(6) T r o u b l e s h o o t i n g M a r g i n a l P e r f o r m a n c e
In most cases the troubleshooting chart, Table 102, will localize afailure to the point where
simple voltage and resistance measurements will enable the technician to locate the specific
malfunctioning component. In some cases, however, failure of the equipment will be evidenced
by marginal performance. For instance, it will take bearings, but slowly. The indicator pointer
may hunt excessively, or the sensitivity or selectivity of the equipment may be inadequate. In
cases such as these proceed as follows :
( a ) C h e c k t h e I n s t a l l a t i o n
Apoor installation is frequently the cause of marginal performance. Use Table 103 to
c h e c k t h e i n s t a l l a t i o n .
!
T A B L E 1 0 3
I N S T A L L A T I O N C H E C K
R E M A R K S
W H A T T O C H E C K H O W T O C H E C K
Mountings must not be loose.
C h e c k f o r c o r r o s i o n a n d b r o k e n
s e n s e a n t e n n a w i r e .
Gently vibrate sense antenna while
observing connections to fuselage.
1 . S e n s e A n t e n n a 1 .
C h e c k t o s e e t h a t s t a n d - o f f i n s u l a ¬
t o r s a r e c l e a n a n d i n g o o d c o n d i t i o n .
2 .
T h e r e m u s t b e n o l o o s e n e s s i n
fasteners; the ground connec¬
tions to cabling must be secure
a n d n o t c o r r o d e d .
3 . E x a m i n e s e n s e a n t e n n a c o n n e c t i o n s
t o r e c e i v e r .
(
Check for missing bolts and
dented or torn housing. Check
that housing is free of paint.
C h e c k f o r l o o p c o n n e c t o r p i n
c o r r o s i o n .
1. Examine antenna housing and check
t h a t l o o p i s f a s t e n e d t i g h t a g a i n s t
a i r c r a f t s k i n .
2 . E x a m i n e l o o p c o n n e c t i o n s t o r e c e i v e r .
2 . F i x e d L o o p
3 . C h e c k t h a t l o o p l e a d - i n i s o f t h e
recommended type and length.
L o o s e c o n n e c t i o n s c a n c a u s e
i n t e r m i t t e n t o p e r a t i o n .
1 . B e s u r e a l l c a b l e c o n n e c t o r l o c k i n g
rings are tight.
2 . C h e c k t h a t a l l c o m p o n e n t s a r e
p r o p e r l y b o n d e d t o t h e a i r f r a m e .
1 . R o t a t e i n b o t h d i r e c t i o n s .
3 . A D F R e c e i v e r , a n d s e r v o
a m p - i n d i c a t o r .
Must turn freely and not bind.
Listen for positive switching
a c t i o n .
4. Tuning control
5 . B a n d s w i t c h 1 . C h a n g e b a n d s .
Binding or too loose operation
c a n r e s u l t i n e x c e s s i v e n o i s e .
Panel lamp should light, and
e q u i p m e n t o p e r a t e a s a
c o m m u n i c a t i o n s r e c e i v e r .
1 . R o t a t e b o t h d i r e c t i o n s .
6 . V O L c o n t r o l
1 . S e t t o R E C .
7 . F u n c t i o n s w i t c h
I
A p r i l 1 9 6 5
( R e v i s e d J a n u a r y 1 9 6 8 )
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