Tandy CM-4 User Manual

ALIGNMENT
INSTRUCTIONS
Mote:
This
adjustment
requires
the
connection of
a personal
computer
to
the Monitor.
Although
the
Monitor
is ad-
usted
before
it
Is
delivered, readjustment
may
be
re-
quired
when
the
setting
position
is
changed
or
when
i
component
is replaced.
1.
B+
Power Circuit
Adjustment
(Instrument
in use: a
20
kohm/V
tester)
1)
Be
sure that the
AC line
voltage is
above 1 14V.
2)
Rotate
the B
+ voltage
adjusting control
(R707)
to
provide a
DC
voltage of
1 16V
between
TP91
and
ground.
Mote
1
:
If the AC
line
voltage
is below
1
14V,
the
DC
voltage may
not increase
to 1
1
6V,
but
this
is
not a
problem
related
to
this
adjust-
ment.
If
the value
of
1
16V
DC
is almost
reached, the adjustment
is
enough.
-Mote
2:
Clockwise rotation
of the B+
voltage
ad-
justing control
will
increase
the
B +
power
supply
voltage.
2.
Horizontal Hold Adjustment
(1)
Operate
the computer in
such
a
way
that
the
let-
ters
"H"
cover
the
entire screen
(data display
peri-
od:
44.698
/*S
horizontal, 14.33
mS vertical).
(2)
Adjust the horizontal hold control
(R607) until
the
picture
on
the
screen becomes
still
(synchronized).
(3)
Turn the power
switch on
and off
several
times
to
check that
the
picture
does
not
fluctuate.
3.
Vertical Size Adjustment
(1
)
Operate
the computer in
such
a
way that the
let-
ters "H" cover the
entire screen
(data
display
peri-
od:
44.698
mS
horizontal,
14.33
mS
vertical).
(2)
Adjust the vertical size
control (R507)
so
that
the
height
of
the
displayed pattern
is 170
mm.
4.
Focusing
(1) Operate the
computer to
display
the
alphabetical
characters
on
the screen.
(2) Set
the
brightness control
at
the center
position.
(3)
Rotate
the focus
adjusting control (part
of
T602)
for
the best
focus.
(4)
Change
the
position
of the brightness
control
to
confirm
that
the
picture remains
focused.
5.
High
Voltage
Check
High
voltage
is
not
adjustable
but
must be checked
to
verify
that
the
Monitor
is
operating within
safe
and ef-
ficient
design
limitations
as
specified.
1
.
Operate the display
Monitor
for
at
least
1
5
minutes
at
1 20V
AC
line voltage
with
the computer
display-
ing
high intensity
white
pattern.
2.
Turn
off
Switch
SW851
on
PCB-B.
3. Rotate
the screen
control
(on T602)
to
the
maxi-
mum
(counterclockwise)
end
of
its rotation.
4. Connect
an
accurate,
high-voltage meter
to
the
CRT anode.
Check
that the
reading is approximate-
ly 22.0kV and
23.0kV
(at
beam current).
If a correct
reading
cannot
be
obtained, check
the cir-
cuitry for malfunctioning
components.
On
completion
of
the voltage check, readjust the screen control for
proper
operation as detailed in the "Black
and
White
Tracking"
procedures.
6. Vertical-Linearity
Adjustment
1
.
Operate
the
computer
in such a
way
that the
let-
ters "H" cover
the
entire screen (data display peri-
od: 44.698
/iS
horizontal,
14.33
mS vertical).
2. Adjust
the
V-Lin.
control
(R526)
until the height
of
a character varies
no more than 1
percent from
the
average
character size.
7. X-ray
Protector Circuit
Test
After service
has
been
performed
on
the
horizontal
deflection
system,
the
high
voltage system and
the X-
ray
protector
circuit must
be tested
for
proper
opera-
tion as
follows:
1
.
Apply
1
20VAC,
using
a variac transformer
for ac-
curate
input voltage.
2.
Operate
the
computer
in such
a way that
the
en-
tire
screen displays
a high
intensity
white
signal
(data
display
period:
44.698
/*S
horizontal,
1 4.33
mS
vertical).
3. Check
the voltage of
test
point TP601 .
(Its
voltage
should
be
about
17.5VDC.)
4.
Connect
the
cathode
of
diode D503 and
TP601
through
a 6.8K ohm, 1/2W resistor.
5.
To
start
operation,
remove the resistor
and
touch
the
IC601
(9)
pin-to-chassis ground
with
a short
clip
lead.
(Remove
the short clip
lead
as
soon
as
the
set
operates
again
with
a normal
picture).
6. Connect
the short-clip
lead
between TP602
and
chassis
ground. When
these
points are
connect-
ed,
the
operation
of
the horizontal
osc. must stop.
7.
To
start
operation,
remove
the short-clip
lead when
the set
begins
operating
again
with
a
normal
picture.
8.
If
the operation
of
the horizontal
osc.
does not
stop
in
steps
4
and
6,
the
circuit
must be repaired
be-
fore the
set
is
returned
to
the
customer.
14

Tandy CM-4 Specifications

General

Brand	Tandy
Model	CM-4
Category	Monitor
Language	English