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back of the screen. The pattern will appear clearer if the front of
the screen is covered with a dark cloth.
2.
Cover 2 of the CRT Output Lenses with 7 inch square pieces of
cardboard.
3.
Loosen the lens retaining wing nuts on the CRT Output Lens and
Housing Assembly.
4.
Move the wing nut in the slot of the uncovered Lens to locate the
optimum optical focus point (viewing the picture from the back side
of the screen), re-tighten the wing nut.
5.
Repeat steps 2 through 4 for the 2 other Output Lenses.
Screen (G2) Adjustment Procedure
Control Preset Positions
1.
Picture, Sharpness, Brightness, and Tint set to mid-range.
2.
Color setting at minimum.
3.
Tune the set to unused input (AUX-1 with nothing connected
is
good).
4.
Turn all G2 Controls (Bottom Row on the Focus/G2
Distribution
Block) to minimum (fully CCW).
5.
Set the Hi-Lite Controls (on the Signal/Deflection
Module) to their
full clockwise positions.
6.
Set the Lo-Lite Controls (also on the Signal/Deflection
Module) to
their full counter-clockwise
positions.
7.
Connect a DC Voltmeter to the cathode of the Green CRT (Pin 8
of the CRT Socket or either end of R210).
8.
Adjust the Sub-Brightness
Control (R776) to obtain a reading of
195Vdc on the meter.
9.
Remove the DC voltmeter from the Green cathode.
10. Looking
directly
into the Tube Lens, bring up each of the G2
(Screen)
Controts
(bottom
row on the Focus/G2
Distribution
Module) for just barely visible light in each tube.
11. Proceed
to the Gray
Scale
Tracking
and Sub-Brightness
Adjustment.
Alternate Method
1.
Picture, Sharpness, Brightness and Tint set to mid-range.
2.
Color setting at minimum,
3.
Tune the set to unused input (AUX-1 with nothing connected
is
good).
4.
Turn all G2 Controls (Bottom Row on Focus/G2 Distribution Block)
to minimum (fully CCW).
5.
Set the Hi-Lite Controls (On Signal/Deflection
Module) to their full
clockwise positions.
6.
Set the Lo-Lite Controls (also on the Signal/Deflection
Module) to
their full counter-clockwise
positions.
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7.
Short Pins 1 and 6 of the J-Test Connector together.
8.
Connect a 2.4K resistor from Pin 6 of the J-Test Connector to Pin
3 (Red) of the same J-Test
Connector
(this forces
the Red
cathode to 195Vdc).
9.
Adjust the Red G2 (bottom row, left) to just barely tum On the Red
CRT.
10. Now, do the same for the Green Output by connecting the same
2.4K resistor from Pin 6 of-the J-Test Connector to Pin 4 (Green).
Then adjust it's G2 Control (bottom row, middle) while viewing it's
CRT.
11. Finally, the Blue Output by connecting the same 2.4K resistor from
Pin 6 of the J-Test Connector to Pin 5 (Blue). Then adjust it's G2
Control (bottom row, right) while viewing it's CRT.
12. Remove resistor and jumper from the J-Test Connector.
13. Proceed to the Gray Scale Tracking, Sub-Brightness Adjustment.
Gray Scale Tracking, Sub-Brightness
Adjustment Procedure
Note:
Gray Scale
and Sub-Brightness
must be adjusted
after
replacing a Signal/Deflection
Module in the PTV400 Systems.
The following procedure assumes a Gray Scale problem exists
and G2 (Screen Controls) require no further modifications.
Setup Procedure:
1.
Install the new Signal/Deflection
Module.
2.
Turn the set On and tune to a good air or cable channel.
3.
Picture, Sharpness,
Brightness
and Tint set to mid-range.
Color
set to minimum.
4.
Set the Lo-Lite Controls (also on the Signal/Deflection
Module) to
their full counterclockwise
positions.
5.
Set the Hi-Lite Controls (On Signal/Deflection
Module) to their full
clockwise positions.
6.
Adjust the Sub-Brightness
Control (R776) so that the darkest part
of the picture is just barely lit (raster lines just barely visible).
7.
Adjust
any two (2) Lo-Lite
Controls
(one to remain
fully
counterclockwise)
to attain gray in low-light areas of the picture.
8.
Turn down only the Hi-Lite Control that is causing an off-white
condition in high brightness white areas of the picture (if pinkish,
reduce red; if bluish, reduce blue; if greenish, reduce green),
9.
Keep all Hi-Lite Controls as near clockwise as possible. At least
one Hi-Lite Control must remain in it's full clockwise position.
10. Repeat
steps 7 through
9 as needed
to achieve
gray in the
darkest areas of the picture and white in the bright areas. Always
adjust Lo-Lite controls to correct dark areas of the picture and Hi-
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