Color Threshold Control:
Purpose: To prevent erroneous color information on
B/W
transmissions.
1.
Set VHF Tuner to
an
unused channel and color level
control to mid range.
2.
Rotate threshold control clockwise until color confetti
appears in picture.
3.
Rotate control counterclockwise until color confetti
just
disappears from picture.
FIGURE
5-
VIDEO
MODULE
FRAME.
A.P.C. Control:
Purpose: To obtain color synchronization.
1.
Connect a color bar generator to the antenna ter·
minals.
2.
Set
tint
to middle of range.
3.
Place the color align jumper in the align position.
4.
Adiust the A.P.C. control for uniform color from top of
bar to bottom.
NOTE: The bars may not
be
the correct color or
they may change colors.
5.
Place color align switch in normal position.
A.C.C. Control:
Purpose: To set chroma gain.
1.
Connect a color bar generator to the antenna ter·
minals.
2.
Place the color align jumper in the align position.
3.
Place a clip lead from test paints J and
JJ
on the
chroma module.
4
4.
Connect a
DC
meter from test stake Q to ground.
5.
Observe the meter reading.
6.
Remove the jumper from test points J and
JJ.
7.
Adjust the A.C.C. control
for
an
identical meter
reading.
8. Alternately open and short J and
JJ
to
check
for
iden·
tical reading.
Focus: Chassis
Purpose: To obtain best focus.
1.
Set brightness, contrast and chroma for normal pic·
ture.
2.
Adjust for optimum focus in highlights.
Brightness Range and Brightness Limiter Adlustment:
Purpose: To
limit
maximum brightness and prevent picture
blooming.
1.
Wire a
10
K 1/4 watt potentiometer
as
a rheostat and
connect (in series) a3.3 K 1/2 watt carbon resistor(this
assembly to be used in step
8).
2.
Disconnect power from receiver.
3.
Attach a
DC
meter across
R3352.
Attach the negative
lead on stake side of resistor. Set the meter
fo,
a full
scale reading of at least 2
VDC.
4.
Adjust brightness limiter fully counterctockwise, turn
on receiver and allow
to
warm up for five minutes.
5.
Connect a clip lead from the side
of
R2227,
which
faces the vertical heatsink,
to
ground stake next to
221-106.
Adjust black level control
to
mid point(Detent
Position).
6.
In
a lowambient light condition, set(the rear section
of
·black level control) brightness range control
to
just
cut
off
the raster.
7.
Set the rheostat/resistor assembly for maximum
resistance and attach between
T.P.Y.
stake and
ground.
8.
Adjust rheostat to obtain a meter reading
of
1.23
VDC.
Do
not readjust after
this
reading is obtained.
9.
Remove meter from
R3352,
adjust scale
for
a reading
of
5.0
V full scale. Attach meter to pin 1
of
221-96
I.C.
10.
Adjust brightness limiter to obtain 3.3
to
3.6
volts
DC
on
th.e
meter (any voltage in this range is acceptable).
