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8. Alignments
Index of this chapter:
8.1 General Alignment Conditions
8.2 Hardware Alignments
8.3 Software Alignments
8.4 Option Settings
8.5 Convergence and Geometry Adjustments
8.1
General Alignment Conditions
8.1.1
Start Conditions
Perform all electrical adjustments under the following
conditions:
•
Power supply voltage and frequency: 120 VAC / 60 Hz (±
10 %).
•
Connect the set to the mains via an isolation transformer
with low internal resistance.
•
Allow the set to warm up for at least 20 minutes.
•
Measure the voltages and waveforms in relation to chassis
ground (with the exception of the voltages on the primary
side of the power supply).
Caution: never use the cooling fins/plates as ground.
•
Test probe: Ri > 10 Mohm, Ci < 20 pF.
•
Use an insulated trimmer/screwdriver to perform the
alignments.
8.2
Hardware Alignments
8.2.1
VG2 (Screen) Set-up
Preferred Method
1. Connect a Black Level signal to the aerial input of the set.
2. Preset all Screen controls on the Screen/Focus Control
Block to minimum (fully CCW).
3. Connect an Oscilloscope to the Collector of the output
transistor on the Green CRT board. Set the probe to x10.
4. Adjust the Green Screen control until the Black Level is at
172 V.
5. Repeat steps 3 and 4 for the Red and Blue CRTs.
Alternate Method
1. Connect a Black Level signal to the aerial input of the set.
2. Preset all Screen controls on the Screen/Focus Control
Block to minimum (fully CCW).
3. Turn each Screen control clockwise until each CRT is
barely illuminated.
8.2.2
Focus Adjustment
Note: Before beginning the following adjustment procedures
set the customer picture, sharpness, brightness, and tint
controls to midrange and the customer colour control to
minimum.
Electrical Focus Adjustment
1. Remove the back cover of the set and the light shield, then
turn the set on and inject a crosshatch pattern signal into
the antenna terminal.
Note: The crosshatch pattern will appear clearer if the front
of the screen is covered with a dark cloth.
2. Cover two of the CRT output lenses with pieces of
cardboard (or other non-conductive opaque material) to
observe the magnified reflection of the other picture tube
on the backside of the viewing screen.
3. Adjust the CRTs focus control (located on the Screen/
Focus Control Block) for the sharpest raster image.
4. Confirm correct focus by viewing the screen from the front
of the set.
Alignments
EBJ1.0U
5. Repeat steps two through four to adjust the focus of the two
remaining CRTs.
Note: Before beginning the following adjustment procedures,
set the customer picture, sharpness, brightness, and tint
controls to midrange and the customer colour control to
minimum.
Optical Focus Adjustment
1. Remove the back cover of the set and the light shield, then
turn the set on and inject an NTSC crosshatch pattern
signal into the antenna terminal.
Note: The crosshatch pattern will appear clearer if the front
of the screen is covered with a dark cloth.
2. Cover two of the CRT output lenses with pieces of
cardboard (or other non-conductive, opaque material) and
observe the magnified reflection of the other picture tube
on the backside of the viewing screen.
3. Loosen the "lens retaining wing nuts [1]" on the CRT Focus
Assembly.
4. Move the wing nut in the slot of the uncovered lens to
locate the optimum optical focus viewing the picture from
the back side of the screen), then re-tighten the wing nut.
5. Confirm correct focus by viewing the screen from the front
of the set.
6. Repeat steps two through five to adjust the focus of the two
remaining CRTs.
Figure 8-1 Optical focus adjustment
8.
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