Tandy 1400LT Service Manual page 127

Check f o r a low
P u l s e a t P i n 4 of
pPD72065 (IC54)
(CS765 s i g n a l ) q L
o r m a l ?
Check f o r a low
p u l s e a t
RD
( P i n 2 of IC54)
and
fi
( P i n 3 of IC54) of pPD72065.
Check
p u l s e
and
fi
f o r
a low
a t
RD
( P i n 2 of IC54)
( P i n 3 of IC54) of pPD72065.
I
Check
I C 3 .
s i g n a l
( P i n 8 of
Check t h e STEP/
a n d DIRECTION/signa
( P i n 1 0 of IC561
I
Check
IC56,
STEPG5 ( P i n 4 7 of GATE5)
D I R E C G 5 ( P i n 4 6 of GATE5)
FDC37
( P i n 3 7 of I C 5 6 )
and FDC39 ( P i n 3 9 of IC56)
P e r f o r m
a WRITE
o p e r a t i o n .
Check WRITE DATA/
Check IC54
[ a n d IC56
Q
I
5-18