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GENERAL OPERATING INSTRUCTIONS
Turn
On
Printer, Power Inejicator
(0 10)
should be
lit.
Locate
the Self-Diagnostic Switch (SW1) on
th
e rear of
printer.
Switch posi
tion
number 4 is
normal posit
ion
for one
pri nter.
Posit
ion
5
is for two
printers.
Posit
io
n
T is
self-diagnostic
test position
.
The
Printer will cont
in
ue to operate
in
posi
-
t
ion
T until t
he Pri
nter
is turned
Off
or Switch SW1 is
switched to
position
4 or 5_ Do
not
print without
paper
in-
serted
into
printer.
DISASSEMBLY INSTRUCTIONS
CABINET REMOVAL
Rem
ove
clear
dust
cover.
Remove
five screws
from cabinet
bottom
.
Lift
cabi net
top
fro
m un
it.
PRINTER MECHANISM REMOVAL
Loosen fo
ur
screws hold
ing
printer mechanism assembly
to
cabi
net bottom.
Li
ft
assem
bl
y
from
cabi net
bott
om.
TROUBLESHOOTING
POWER
SUPPLY
Printer
will
not
t
urn
On.
Check the AC
Li
ne
Fuse
(F3).
If
Fuse F3 is open, check for shorted Bridge Rect
ifi
er
Diodes
06
and
07.
Also check
Electrolytics
C10 and C13, and the
Power
Transformer
(T1).
Check
DC
Fuse (F 1). If Fuse F1 is
open
,
ch
eck
Zener
Diode
04, Electrolyti
c
C9, and Reg
ulator
IC
(03)
fo
r
short
to
ground. Check DC Fuse (F2). If
Fuse F2
is
open,
check
Zener Diode 05, Regulato
r
Transisto
r
(02),
Regulator
IC
(04), and Electrolytic C12 for short to grou
nd.
If DC
Fuses
(F1 and F2) are
norma
l,
apply
power
and check
for
5.00V
at
pi
n
2
of
IC 03
. If
the
voltage is
missin
g,
check
IC
03
,
Resis
tor
R14 and Zener
Di
ode
04.
Check
for
33.2V
at
th
e
emitter
of Transistor 02, and 20.2V
at
the collector
of
Trans
istor 02
.
If either voltage
is
missing,
ch
eck
IC
04,
Zener Diode
0
5,
and
Resist ors R1 and
R2.
CPU OPERATION
Check for 5.00V
on
pi
n
40 of CPU IC
(P6).
If
5.00V
is
missing,
refer
to
the·
Power
Supply· sectio
n
of
th
is
Tro
ubleshooti
ng
guide.
Verify the 6MHz Crystal
(X1)
is
OSCillating
by
checking
the
waveform
on
pi
n
2
of
IC P6, and
check
for
a frequency
of
6.00MHz.
If
Crystal
X1
is
off freq
uency,
check
Crystal
X1
and Capacitors C14 and C15.
Also ch
eck
IC P6 by
substitu-
tion.
If Crystal
X1 is
func
tioning
normally, check
the
waveform
and log
ic
read ings
on
pins B,
9,
11
and 39 of IC P6.
If
any
wavef
orm
is
missing or
logic
readin
g
is
incorrect, check
IC
P6 by substit
utio
n.
PRINT HEAD
The
Pri nt Head
moves
back and fort
h
but
is
not
printin
g.
Check
for
broken
hammer
on
the
Print
Head and check the
resistance
of
the
Pri nt Head So
lenoid (H1
), wh
ich should
meas
ure 5 Ohms across
Connector
CN10. If
th
e
hammer
or
resi
stance is bad, rep
lace
t
he Print
Head.
Check for 20.2V at t he emitter of
Driver
Transistor (0
1).
If
the voltag
e
is missing, refer
t
o the
"
Power Supply"
secti
on
of
th
is
Tro
ub
leshooti ng
guide.
If the vol
tage
is
normal,
check
Transist
or
01.
If
Tran sistor
01 is
normal,
check
for
pul ses
at pi
n 27 of
t
he
CPU
IC
(P6),
pins
12
and
13
of
Inverter
IC
(PB),
an
d
at pins 7 and 10 of Inverter IC
(P7)
to isolate th
e
defect ive
stage.
If
all
pulses
were present, check
EPROM
IC (P4)
by
subs
ti
tut
ion.
4
HEAD CARRIER ASSEMBLY
Pri
nt
Head
does
not move
back
and
forth
on carriage.
Check
for
19.4BV
across
the Drive
Motor (M1)
. If the voltage
is
normal
, check Motor
(M1),
the
Dot
Sen
sor Assembly
(TR2), and
check
for an obstruction in the drive gear
assembly.
If
19.4BV
across
Motor
(M
1) is miss
ing
,
chec
k
for a low logic
read
ing during
the drive sequence
on
pi
n
16
of Inverter
IC
(P7). If
t
he
read
ing is
not
low, check
fo
r a
high
logic reading
on
pin
30
of
CPU
IC (P6),
and a
high
logi
c
reading on pin 6 of
Inverter
IC (PB) to
isolate the
defect
ive
stage.
LlNEFEED OPERATION
Pri
nter
wi
ll not
advance
th
e
paper.
Check
the
resistance of
the
Linefeed Clutc
h
Solenoid
(H3), which should read
49
Ohm
s across
Con
nector
CN9. If
Solenoid
H3
is normal,
check
for
defect ive mechanical
parts
in th
e Li
ne Feed
Clu
t
ch
Assembly
. Check
for a
low
logic
read ing at pin 12 of
Inverter IC
(P7), and
at
pin
2B
of
CPU
IC
(P6) duri
ng the line
feed
sequence to isolate the defective
stage.
HEAD HOME POSITION OPERATION
Head
wi
ll not
ret
urn
t
o
Home
Position
after printing first
li
ne.
Check for
a
broken
recovery
spring and
also
ch
eck
the
Head
Release Clutc
h
Asse
mbly for
defective parts.
Check the resistance of the H Solenoid (H2), which should
measure
49 Ohm
s
acro
ss
pin
s 1
and
2
of
Con
nector
CNB. If
Solenoid
H2 is
normal,
ch
eck
th
e Ret urn Home
Sensor
(TR
1)
and
check
for
a low
logic
reading
at
pin
13 of
Inverter IC (P7)
and
at
pin
29
of
CPU
IC (P6)
during a return home sequence
to
isolate
the
defec
tive
stage.
PRINTER WILL NOT RECEIVE DATE (SELF
TEST OPERATES)
Prog
ram
Co
mputer to
send
informat
ion to th
e
Printer.
Check f
or
pulses
at
pins
1,4,
6, and 3B
of CPU
IC
(P6).
If
pulses
are
missi ng,
check
the
log
ic readi
ngs
of
IC's
P1, P2,
P3,
and PB
to
iso late
th
e
defective
components
.
SELF TEST DOES NOT OPERATE
Co
nnect
a frequency
cou nter to pin 2
of
CPU
IC
(P6)
and
veri
fy that
th
e 6MHz
Crystal
(X1
)
is
oscillating.
If Crystal
X1
is
fun ction
ing
normall
y,
check IC
P6, EPROM
IC
(P4)
and
LATCH
IC
(P5)
by su bst
itution.
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