Vector 4 - Page 188

SYMPTOM
CHECK NORMAL
' VECTOR 4
TECHNICAL INFORMATION
ABNORMAL
O. Parallel
printer fails to
print, or no rib-
- bon lift(1)
a) U117-12
Active while
printing
Check U120-7, If
normal, replace Ull7,
If abnormal, replace
U120.(2)
b) U120-2, 3, 4, 5, 6
Active lines Check U120-15, 14, 13.
If active, replace
6. Parallel printer
prints "garbage"
Al GRat anaf oasl g sk - s
U92, U118, U119
Active
Replace appropriate
inverter.
7. Keyboard not func- U96-9, U96-25
4,8KHz square wave Isolate to U105, U113,
tioning(3) or failed TxC + RxC Refer to 7b- U114, U117
I ~-on test
b) U96-3 Rx data — refer Check U78-3. If
to Te. normal, replace U78.
If abnormal, replace
keyboard.
c) U96-19 Tx data — replace Replace U96.
Gauk Anr au agt s L anaf e and e o e e e aat g and @ aag . and. ma
U78.
e S anal . e e Ll ey g el e, anal et o ot e By g mal aaar e s
s S A, Sl eute Sut . Snk. aal Sl k. sl Sl ks Saks Sl anks St Suts ke St S
(1) 1t is assumed that the technician has a working knowledge of the 8255.
(2) Inputs to U120 must be active.
If not, check for proper operation of 8255.
)
If
the
keyboard
8251
has
been
properly
selected
and
is
receiving
and
outputting
all
data,
then
check appropriate gate
09-01-82
or inverter.
Replace if defective,
7200-0001
vV 3-5