Table of Contents
Advertisement
T a b l e 5 . 1
S i g n a l
F u n c t i o n
g) P i n 1 0 , 11,
1 4 ,
1 5 , of
U12
R e p r e s e n t s A / D b i t i n f o r m a t i o n .
S i g n a l s
s h o u l d b e v a r y i n g from low ( 0 ) s t a t e t o
h i g h (1) s t a t e .
A l l of t h e d i g i t l i n e s
(D1-4) s h o u l d b e checked
s o t h a t t h e s e
l i n e s go h i g h a t some p o i n t .
These s i g n a l s
s h o u l d a l s o b e p r e s e n t a t t h e a p p r o p r i a t e
I/0
p o r t l i n e s of U 1 7 .
I f s i g n a l s a r e n o t
p r e s e n t , r e p l a c e
U21.
I f s i g n a l s are p r e s e n t ,
b u t do n o t a p p e a r a t U 1 7 , r e p l a c e U12.
h ) P i n 4 , 6 , 8 , 1 1 of
U18
A r e l i n e s t h a t s e l e c t t h e a p p r o p r i a t e PROM.
I f n o t p r e s e n t , check f o r o p e r a t i o n of U 1 8
( 7 4 0 0 ) as d e s c r i b e d i n T a b l e
5 . 1 ,
s i g n a l
c .
i ) P i n 6 of U 7
Should b e same a t P i n
12
of
U21.
If s i g n a l
n o t p r e s e n t , c h e c k i n t e r c o n n e c t i o n s on
P.C.
b o a r d .
S i g n a l p a t h s should a l s o b e checked.
I f s i g n a l s are p r e s e n t a t s o u r c e
components and n o t a t d e s t i n a t i o n components, a p r i n t e d c i r c u i t board problem
r e q u i r i n g a r e p a i r of t h e p r i n t e d c i r c u i t f o i l may b e r e q u i r e d .
checks between p o i n t s w i l l t u r n up any unwanted open c i r c u i t s i n s i g n a l p a t h s .
I f t h e s i g n a l s a t t h e component p i n s o u t l i n e d i n T a b l e
5 . 1 a r e
p r e s e n t and
a problem s t i l l
e x i s t s , check T a b l e 5 . 2 f o r a
l i s t of problems and s o l u t i o n s
f o r t h e i n s t r u m e n t .
C o n t i n u i t y
Advertisement
Table of Contents
