Tandy 1400LT Service Manual page 120

@ Internal Keyboard Check
Q
Check i f keyboard
c o n n e c t o r
i s loose.
I
Check t h e keyboard
S e l e c t S i g n a l
P i n 1 7
of
GATE4.
(Low : I n t e r n a l )
I
NO
1
I
Check GATE4
1
I 1
R e p l a c e t h e
keyboard u n i t .
Y E S
1
I
Keyboard u n i t
I
I
f a i l u r e .
I
I
Keyboard c o n t r o l
f a i l u r e .
Check t h e
key s w i t c h .
ICheck t h e key
matrix.1
C80 and
C81
I
Check t h e keyboard d a t a
I
GATE4
-
P i n 6 - 1 3
I
Check GATE4
5-1 1