Service manual
TROUBLESHOOTING
GUIDE
(Continued)
SYMPTOM
3:
Part
of
a printed character is missing.
POSSIBLE CAUSE
SOLUTIONS
1 . Ribbon is
worn
out.
Replace
the
ribbon cartridge.
2. Head
shift
lever is
out
of
Re-set
the
shift
lever.
position.
3. Print head on flexible cable is Check flexible cables and
wiring
harness
for
defective.
continuity.
Check
the
print
head
by
disconnecting
the
wire
harness
connector
J 1
from
P1.
With
an
ohmmeter
set
on
the
200
ohm
range, place one
of
the
leads
on pin
10
of
J 1 and
the
other
lead on pins 1
through
8
of
J 1. A resistance
of
10
to
14
ohms
at
each pin indicates a good
print
head. Replace
if
necessary.
4.
Interference (NOISE) in
the
Place printer in area void
of
external interference
proximity
of
the
printer. (i.e.,
motors,
machinery).
SYMPTOM
4:
Paper does
not
feed
correctly.
POSSIBLE CAUSE SOLUTIONS
1. Physical interference
with
Check
for
obstruction
of
the
paper feed path -
proper paper feed.
paper guide, platen,
tractors.
Check
that
the
left
tractor
is positioned
to
the
ex-
treme
left
and
the
right
tractor
is adjusted
to
the
correct
paper
width.
Check
that
the
paper holes align
with
the
tractor
pins correctly.
Check
that
the
paper release lever is in
the
correct
position - in
the
direction
of
the
arrow
for
tractor
feed or opposite
the
arrow
for
friction
feed.
Check
that
no more
than
the
maximum
allowable
sheets
of
paper are being used.
2. Paper feed
motor
defective.
With
power
off,
check
motor
with
an
ohmmeter.
Set on
the
200
ohm range. A good paper feed
motor
should need around
50
ohms
between
pin
14
of
J1 and pins
25,26,27,
and
28
of
J1.
Check
for
good mechanical and electrical connec-
tions
to
the
motor
and
its
wiring
- see
wiring
diagram on page
28.
Check
for
+
26
VDC
supply
to
the
motor.
3.
Circuit
failure on PCB.
Check
motor
circuitry
on PCB. See
circuit
theory
on page
12
for
proper
circuit
operation.
20