Tandy 1400LT Service Manual page 137

@ External FDD Troubleshooting
I s b o o t s e l e c t s w i t c h
Has
t h e l o c a t e d d i s k e t t e
b e e n p r o p e r l y i n i t i a l i z e d ?
Check t h e
c o n n e c t o r s
a n d
c a b l e c o n n e c t e d t o t h e
FDD.
0
I
I
---
Check t h e
l e v e l
o f "RESET765"
s i g n a l
when FDC
i s
t u r n e d
on
P i n 5 3
of
GATES.
I t s h o u l d b e Low.
IES Check
Check t h e f r e q u e n c y
a t
P i n 3 of IC57.
I t
m u s t be 4MHz.
1
Check CTL6, C 9 1 ,
a n d C92.
(The f r e q u e n c y i s 16MHz)
5-28