Paper Feed Motor - Epson MX-80 IIIF/T Technical Service Data

TROUBLESHOOTING
(Continued)
PAPER FEED
MOTOR ASSEMBLY
(Continued)
If
the
collector
waveform
is
missing
at
one
of
the Transistors,
check
for
the
waveform shown
in
Figure 4
at
the
base
of
the
Transistor.
If
the
base waveform
is
present,
check
the Tran-
sistor,
and
associated
components,
that
has
the missing
col-
lector
waveform.
If
the Transistor and
associated
com-
ponents check
good,
check
the
Paper Feed Motor
Assembly
(M2).
If
the
waveform on
the base
of
the Transistor
is
miss-
ing,
check
the buffers driving the Transistor and check
Slave
Microcomputer
IC (9B) by substitution.
2V
5ms
OV
DC
REFERENCE
Figure
4
If
the collector
waveform does
not appear on any
of
Tran-
sistors
Q14
thru Q17,
check
the voltage
on
the
collector
of
Line
Feed
Driver
Transistor (Q20)
after pressing the
FF
but-
ton.
The
voltage should
go
up
to 25.5V.
If
25.5V
is
missing,
check
the emitter and base
voltage of Transistor Q20.
If
the
emitter voltage
is
missing,
refer to the
"Power
Supply"
sec-
tion of this
Troubleshooting
guide.
If
the base
voltage
does
not drop
to
about 24.8V
after pressing the
FF
button,
check
Transistor
Q20 and
associated components.
Also,
check
the
logic
probe readings on
pins 6
and
1 1
of IC
5E and
pins
1
and
2 of
IC 6D.
If
the probe readings
are not correct,
check
IC's 5E,
6D
and
9B
by
substitution.
If all
readings
are correct,
check
the
Paper Feed Motor Assembly.
TIMING BELT
MOTOR
ASSEMBLY
Timing
Belt
Motor Assembly
(M1)
does
not
move
the
Print
Head back and
forth.
Check
the operation
of
the
Home
Posi-
tion
Sensor
(PT1)
and
the
PTS
(Position
Timing Sensor) Sen-
sor
(PT2).
Check
the
Home
Position
Sensor
by monitoring the
logic
probe
reading
at
pin 20 of Plug
CN6
while
sliding
a piece
of
paper
in
and
out
of
the
slot
in
the
Home
Position
Sensor.
The
probe should
read low with the paper out
of
the
slot
and
high
with the
paper
in
the
slot.
If
the
Home
Position
Sensor
checks
good,
check
the
logic
probe reading
at
pin 11 of IC
3E
while sliding the
paper
in
and
out of the
Home
Position Sen-
sor.
The
probe should read high with the paper
out of the slot
and
low with the paper
in
the
slot.
If
the probe reading
is
not
correct,
check
the
components
connected
to pins 12
and
13
of IC
3E and check
IC
3E and
Slave Microcomputer
(9B)
by
substitution.
Check
the
PTS Sensor by checking
for
pulses with a
logic
probe
at
pin 19 of Plug
CN6
while
manually moving
the
Print
Head.
If
the
PTS Sensor checks
good,
check
for pulses
at
pin
10 of IC
3E
while
manually moving
the
Print
Head.
If
the
pulses
are missing,
check
the
components
connected
to
pins
8
and
9 of IC
3E and check
IC's
3E and 9B and
Interface IC
(8B)
by substitution.
If
the
sensor
circuits
check
good,
check
for
the
waveform
shown
in
Figure 5
on
the collectors
of
Carriage Driver Tran-
sistors (Q10
thru Q13)
while the
printer
is
printing.
YYYYS
Figure
5
52V
5ms
0V
DC
REFERENCE
If
the collector
waveform
is
missing on one
of
the Tran-
sistors,
check
for the
waveform shown
in
Figure 6
at
the
base
of
the Transistor.
If
the base waveform
is
present,
check
the
Transistor,
and
associated components,
that
has the missing
collector waveform.
If
the transistor and associated com-
ponents check
good,
check
the
Timing
Belt
Motor Assembly.
If
the base waveform
is
missing, check
the buffers driving the
Transistor
and check
IC
9B
by substitution.
s / < * y
o
Figure
6
1.4V
|
5ms
0V
DC
REFERENCE
If
the collector
waveform does
not appear
at
any
of
the Tran-
sistors
Q10
thru Q13,
check
for
25.4V
on
the collector
of
80
Column
Driver Transistor (Q18) and
14.00V
on
the collector of
132
Column
Driver Transistor (Q19) while
printing.
If
the
voltages
check
good, check
the Carriage Return Motor.
If
25.4V
is
missing from
the collector of Transistor Q18,
check
for
26.3V
on
the
emitter.
If
26.3V
is
missing, refer to the
"Power
Supply"
section
of this
Troubleshooting
guide.
NOTE:
If
the
printer
is
printing
in
the
compressed mode,
the
voltage
on
the collector of Transistor
Q18
will
stay
at
0V.
If
the emitter voltage
of
Transistor
Q18 checks
good,
check
the
logic
probe readings on
pins
8,
9
and
10
of IC
6E and
pins 5
and
12
of IC
5E
while
printing.
If
the
probe readings
are
good,
check
Transistor
Q18
and
associated
components.
If
the
pro-
be readings
are not correct,
check
IC's
5E,
6E and 9B by
substitution.
If
14.00V
is
missing from the
collector of Transistor Q19,
check
for
14.13V
on
the emitter
of
Transistor Q19.
If
14.13V
is
missing,
refer
to
the
"Power Supply"
section
of this
Troubleshooting
guide.
If
14.13V
is
present,
check
the logic
probe readings on
pins 3
and
4 of IC
6D
and
pins 7
and
10 of
IC
5E
while
printing.
If
the probe readings
are good,
check
Transistor
Q19
and check
the
components
associated with
Transistor Q19.
If
the
probe
readings are not correct,
check
IC's 5E,
6D and 9B
by
substitution.
CO
o
COMPUTERFACTS-OF-THE-MONTH
SET
NO.
CF2
FOLDER
CP1
13